yacht keel design

Practical Boat Owner

• Digital edition

Keel types and how they affect performance

• Peter Poland
• June 19, 2023

Peter Poland looks at the history of keel design and how the different types affect performance

The Twister is a well-proven example of a generation of production yachts with ‘cutaway’ full keels and keel-hung rudders. Credit: Graham Snook/Yachting Monthly

Having been a boatbuilder for around 30 years until the very early ‘noughties’, I’ve already witnessed – and even taken part in – a lot of changes in the world of yacht design and building.

Yacht design originally evolved as traditional workboats developed into leisure craft.

In his History of Yachting , Douglas Phillips-Birt writes that the Dutch, who gave the name ‘yacht’ to the world, were probably the first to use commercial craft for pleasure in the 16th century.

They created the first yacht harbour in Amsterdam in the 17th century.

When the schooner America visited the UK in 1851 and raced around the Isle of Wight, this led to the America’s Cup and the resulting merry-go-round of race-yacht design that continues to this day.

The Jeanneau Sun Odyssey 35 offers three different fin keel configurations with different draughts plus a lifting keel version with a centreplate housed in a shallow winged keel stub. Credit: David Harding

The creation of what is now the Royal Yachting Association ( RYA ) in 1875 led to the introduction of handicap rules, establishing the sport in Britain.

These rating rules – and their numerous successors down the ages – have helped determine the evolution of yacht design and keel shapes.

Many early yachts were closely based on workboats, commercial cargo carriers or even privateers and naval vessels.

Initially, the ballast was carried in a long keel and the bilges .

New racing rules of the day taught designers to seek and tweak performance-enhancing features.

Maybe racing did not always improve the breed, but it certainly kept it moving ahead.

Artwork inspired by Ted Brewer’s illustration of keel types (excluding centreplate or lifting keels)

The late, great designer David Thomas believed that fishing boats, pilot cutters and oyster smacks had a large influence on the sport of sailing.

Each type of workboat was built to fulfil a specific purpose. And many had to be sailed short-handed while carrying heavy cargoes.

So they needed to combine form and function, sail well and be able to cope with heavy weather.

Proof of the versatility of working boat designs was provided by Peter Pye and his wife, Anne.

They bought a 30ft Polperro gaff-rigged fishing boat (built by Ferris of Looe in 1896) for £25 in the 1930s.

Having converted her to a sea-going cutter, and renamed her Moonraker of Fowey , they sailed the world for 20 years.

It proves how the simplest working boat design can cross oceans and fulfil dreams.

Racing influence on keel types and design

Most early yacht designs were schooners, but during the latter half of the 19th century the gaff cutter rig started to dominate the scene.

Many notable yachts were built at that time and the most important racing design was probably the yawl Jullanar (1875).

Designed and built by the agricultural engineer EH Bentall, she had, in his own words, “the longest waterline, the smallest frictional surface, and the shortest keel”.

She proved to be extremely fast and in her first season won every race she entered. Jullanar became the forerunner of such famous designs as GL Watson’s Thistle (1887), Britannia (1893), and Valkyrie II and Valkyrie III , both of which challenged for the America’s Cup during the 1890s.

Compare the She 36’s graceful overhangs with the vertical stems and sterns of most modern cruiser/racers

In the USA, Nat Herreshoff experimented with hull forms for racing yachts and produced the ground-breaking Gloriana in 1890.

She was a small boat for the times, with a waterline length of 46ft. Her hull form was very different to anything yet seen in the USA.

With long overhangs at bow and stern, her forefoot was so cut away that the entry at the bow produced a near-straight line from the stem to the keel.

It was a revolutionary design, and nothing at the time could touch her on the racecourse.

Many French models, such as this Beneteau, have opted for substantial pivoting keels. Credit: Peter Poland

Herreshoff wrote: “Above the waterline everything on Gloriana was pared down in size and weight… and every ounce of this saving in weight was put into the outside lead.”

Early English rating rules produced the ‘plank-on-edge’ yacht, where the beam became narrower and the draught got deeper.

New rating rules were then adopted to discourage this extreme type and eventually the Universal Rule was introduced in the USA and the International Rule – which produced the International Metre Classes – took over in Europe.

Yet again, racing rules proved to be a major influence on design development.

By the start of the 20th century the big, long-keeled racing yachts like the J Class attracted a lot of public attention, but after World War II everything changed. Yachts built to the Universal Rule fell from favour.

The age of the racing dinghy arrived and the ocean racer became the performance yacht of the future.

To new extremes

A 300-mile race from New York to Marblehead saw the start of offshore racing and the first Bermuda race was run in 1906.

The British were slower to compete offshore, but in 1925 seven yachts took up the challenge to race round the Fastnet Rock, starting from the Isle of Wight and finishing at Plymouth.

EG Martin’s French gaff-rigged pilot cutter Jolie Brise won the race and the Ocean Racing Club was formed.

In 1931 this became the Royal Ocean Racing Club (RORC), which remains the governing body of offshore racing in Britain.

The ‘cutaway’ modified full keel was famously used by Olin Stevens on his mighty Dorade. Credit: Christopher Ison/Alamy

The early competitors in RORC races were long-keeled cruising boats, many of them gaff rigged and designed for comfort and speed.

But everything changed in 1931 when the young American Olin Stephens designed and then sailed his family’s 52ft yawl Dorade across the Atlantic to compete in that year’s Fastnet race.

She won with ease. Then she did it again in 1933, having first won the Transatlantic ‘feeder’ race.

At 52ft LOA, with sharp ends and 10ft 3in beam, some said Dorade looked like an overgrown yawl rigged 6-metre. But her triple-spreader main mast was revolutionary. As were her cutaway forefoot, lightweight construction, deep ballast and 7ft 7in draught.

Dorade took the long keel format to new extremes.

In the USA, the Cruising Club of America (CCA), founded in 1922, played much the same role as the RORC did in Britain.

It introduced its own rating rule which influenced the evolution of yacht design in the USA.

The Elan 333. Both the deep (1.9m) and shallow (1.5m) draught models feature an elegantly faired bulb keel and spade rudder. Credit: Peter Poland

Beam was treated more leniently under the CCA rule, so wider American designs later offered more space for accommodation and a bit more inherent form stability than RORC-rule inspired yachts.

Many famous designers of long-keel racing yachts at this time developed their skills at the yachtbuilding firms they ran, such as William Fife II (1821–1902), his son William III (1857–1944), Charles E Nicholson (1868–1954) of Camper & Nicholsons and Nat Herreshoff of Bristol, Rhode Island.

Around the same time several British yacht designers made their names, including George L Watson (1851–1904) who set up one of the earliest Design Offices and Alfred Mylne (1872–1951), who designed several successful International Metre Class yachts.

Norwegian designers Colin Archer (1832–1921) and Johan Anker (1871–1940) also joined the party.

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In 1873 Archer designed the first long keel Norwegian yacht, but his real interest was work boats – pilot boats, fishing craft, and sailing lifeboats – some of which were later converted into cruising yachts.

Erling Tambs’s Teddy was a classic Colin Archer long keel canoe-stern design in which he wandered the globe with his young wife and family.

He proved the seaworthiness of Archer’s yachts, as well as their speed, by winning the 1932 Trans-Tasman yacht race.

Fellow Norwegian Johan Anker – a one-time pupil of Nat Herreshoff – became equally famous, thanks to his Dragon-class design that still races today.

As a new generation of designers arrived on the scene in the 1930s, hull tank testing became more sophisticated.

Long keel designs became as much a science as an art.

The leader of this new wave of designers, Olin J Stephens, had been a junior assistant to Starling Burgess who designed race-winning J Class yachts, including the iconic Ranger .

Tank testing was then in its infancy but the USA was ahead of the game and Stephens stored away everything that he learned. He enjoyed a head start over his contemporaries.

Keel types: Fin keels

Between the 1930s and the 1980s more fin keel designs began to arrive on the scene and his firm Sparkman & Stephens produced many of the world’s top ocean racers.

He also designed America’s Cup 12-Metres that defended the cup up to 1983 until Ben Lexcen’s winged keel shook the sailing world.

Many S&S fin keel and skeg production boats – such as the Swan 36 (1967), 37, 40, 43, 48, 53 and 65, She 31 (1969) and 36 and S&S 34 (1968) – still win yacht races and are much sought after as classics.

The S&S 34 has several circumnavigations to its name. Stephens, of course, had his rivals.

Among these was the Englishman Jack Laurent Giles, whose light displacement race-winner Myth of Malham had one of the shortest ‘long keels’ of all time.

(L-R) A Sigma 38 designed by David Thomas and Gulvain (1949) by Jack Giles as a development of his Fastnet-winning Myth of Malham have very different keel types. Credit: Peter Poland

The Dutchman EG Van de Stadt designed the Pioneer 9 (1959) which was one of the first GRP fin keel and spade rudder racers.

Towards the end of his career, Olin Stephens also came up against Dick Carter, Doug Peterson, German Frers and the Kiwis Ron Holland and Bruce Farr.

The development of new shaped keels went hand in hand with this rapid evolution in yacht design.

The full keel, as still found on motor-sailers such as the Fisher range, gave way to the ‘cutaway’ modified full keel as famously used by Olin Stephens on his mighty Dorade , designed back in the late 1920s.

She still wins ‘classic’ yacht races in the USA. American designer Ted Brewer wrote in ‘ GoodOldBoat ’ that Dorade’s offshore racing successes proved that the full keel is not essential for seaworthiness.

The Nicholson 32’s modified ‘cutaway’ long keel results in excellent performance and handling. Credit: Genevieve Leaper

As a result of its improved performance and handling, the modified ‘cutaway’ long keel caught on quickly and became the standard for around 35 years.

This keel type is found on numerous popular designs such as the Nicholson 32 , 26 and 36, Twister 28 and many Nordic Folkboat derivations.

The modified full keel format had a cutaway profile, giving good handling and directional stability while having less wetted surface than the full keel designs.

These yachts can perform well in all conditions and have a comfortable motion.

Even though they are generally of heavier displacement than fin keelers, they are not much slower in light airs , despite their added wetted surface area.

Their main drawback is a wide turning circle ahead and reluctance to steer astern when under motor.

Keel types: Increased stability

The modified full keel was subsequently cut away more and more for bluewater and inshore racers in an attempt to reduce wetted area until, finally, some designers took it to extremes.

As a result, much-reduced directional stability produced craft that were difficult to steer in breezy conditions, broaching regularly.

Whereupon the fin keel and skeg-hung rudder took over, reinstating increased directional stability, improving windward ability, reducing drag and restoring – when under power – control astern and on slow turns.

This fin and skeg format was later followed by the NACA sectioned fin keel with a separate spade rudder .

Soon, many performance cruisers followed this race-boat trend.

The Hanse 430 has a spade rudder and bulbed keel (draught 2.16m or 1.79m shoal draught. Credit: Peter Poland

Many builders now also offer shoal draught fin keel options and shallower twin rudders.

Some, such as Hanse, incorporate L- or even T-shaped bulbs on some Hanses and Dehlers at the base of finely shaped cast iron fins.

A new international competition had encouraged the initial development of modern fin keel yacht designs.

The revamped One Ton Cup was launched in 1965 for yachts on fixed handicap ratings (typically around 37ft long).

This spawned later fixed-rating championships for Quarter Tonners (around 24ft), Half Tonners (around 30 ft), Three-Quarter Tonners (around 33ft), and finally Mini-Tonners (around 21ft).

All these yachts were eventually handicapped under the International Offshore Rule (IOR) that replaced the old RORC and CCA rules.

The revamped One Ton Cup helped encourage the developed of modern fin keel designs. Credit: Getty

Countless production fin keel cruisers designed and built in the 1970’s to 1990’s boom years were loosely based on successful IOR racers that shone in the ‘Ton Cup’ classes.

The IOR handicap system’s major drawback was its Centre of Gravity Factor (CGF) that discouraged stiff yachts.

Once the international IRC rule replaced the IOR, more thought was given to increasing stability by putting extra weight in a bulb at the base of the keel.

GRP production boats followed suit. The keel foil’s chord needed to be wide enough to give good lateral resistance (to stop leeway), yet not be so wide as to add unnecessary drag.

Exaggeratedly thin foils are not suited to cruising yachts because they can be tricky upwind.

Tracking is not their forte and they can stall out. A bonus was an easier ride downwind thanks to wider sterns.

Keel Types: Lead or iron?

And then there is lead. Almost every production cruiser has a cast iron keel for one simple reason; it is much cheaper than lead. But it’s not as good.

Not only does it rust; it is ‘bigger’ for the same given weight. A cubic metre of iron weighs around 7,000kg, while the same cubic metre of lead weighs around 11,300kg.

An iron keel displaces far more water (so has more drag) than the same lead weight. We had always put iron keels under our Hunters – as did our competitors.

But when we came to build the Van de Stadt HB31 cruiser-racer, designer Cees van Tongeren said “No. We use lead.” “Why?” I asked. Cees replied: “If we use iron, the keel displaces more, so the boat sails worse.”

Rustler 36 long keel’s cutaway forefoot delivers responsiveness and manoeuvrability – a reason the design is so popular in the Golden Globe Race. Credit: Beniot Stichelbaut/GGR/PPL

Which explains why top-flight race boats have lead keels – or at the very least composite keels with a lead bulb or base bolted to an iron upper foil, thus lowering the centre of gravity (CG).

Some modern production cruiser-racers offer high-performance lead or lead/iron composite keels – but at a price.

Many Danish X-Yacht and Elan race-boat models, for example, have a lead bulb on the base of an iron NACA section fin.

Rob Humphreys, current designer of the popular Elan and Oyster ranges, said: “The T-keel is good if you have sufficient draught available. If not, the fin element has too short a span to do its job. This is because the T-bulb doesn’t contribute as usefully to side force as a ‘filleted L-bulb.’

“I developed and tested this shape (a blended-in projection off the back of the main fin) for the maxi race boat Rothmans in 1988/9, and have since used it on the Oysters and Elan Impressions. The ‘filleted’ keel we tested for Rothmans had slightly more drag dead downwind (more wetted area) but was significantly better when any side-force occurred; and side-force goes hand-in-hand with heel angle – which is most of the time! When the model spec allows for reasonable draught, the keel option with the lowest centre of gravity will invariably be a T-keel, with a longer bulb giving the greatest scope for a slender ballast package. An L-keel is a compromise and doesn’t suffer from the risk of snagging lines, mooring warps, and nets. [many modern production cruisers have 100% cast iron L- or T-shaped keels]. A lead bulb is preferable to a cast iron keel in terms of volume and density, but it costs more. However, a lead T-keel in a production environment will almost certainly use a cast iron or SG Iron fin, which may rust.”

The Mystery 35, designed by Stephen Jones and built by Cornish Crabbers, has a lead fin keel. Photo: Michael Austen/Alamy

Rustler Yachts also uses lead instead of iron for their keels.

The Rustler 36 long keel (designed by Holman and Pye and winner of the 2018 Golden Globe Race) has a cutaway forefoot to improve responsiveness and manoeuvrability.

The long keel creates more drag but, as with the Rustler 24, the cutaway forefoot makes the 36 more nimble than a full long keel boat, which are more difficult to manoeuvre in reverse under power.

The rest of Rustler’s offshore range – the Rustler 37, 42, 44 and 57 – designed by Stephen Jones – have lead fin keels.

As does his Mystery 35 built by Cornish Crabbers.

These offer an excellent combination of directional stability, performance and lateral stability. The yachts track well, are comfortable in choppy seas, and have good manoeuvrability, all without the flightiness of shorter chord fin keels found on many production family cruisers.

A digital future

Influential designer David Thomas said: “When I started designing, I integrated sharp leading edges to the keel; until someone told me a radius was better. Then we were all taught that an elliptical shape was better still. With the advent of computers, designers could better visualise the end-product; and clever ‘faring programs’ speeded this up.”

So where next? A combination of lighter and stronger materials, rapidly developing computer programs, a desire for maximum interior volume and low costs has led us to today’s production yacht.

Twin rudders improve the handling of broad-sterned yachts when heeled.

The IRC rating rule permits low CG keels, wider beam and near-vertical bows and sterns.

And designers now have an array of new computer tools at their disposal. But maybe there’s still that element of black magic?

As David Thomas so succinctly said: “You can design a yacht 95% right, but the last 5% can be down to luck.”

Keel types : the pros and cons

Full length keel

The Fisher 31 and many motor-sailers have long keels. Credit: Peter Poland

Pros: Directional stability. Heavy displacement leading to comfort at sea.

Cons: Poor windward performance. Large wetted surface leads to drag. When under power at low speeds, the turning circle is wide unless fitted with thrusters. The same applies to manoeuvring astern.

Cutaway modified long keel form with keel-hung rudder

Pros: Reduced wetted surface area leading to increased boat speed. Better windward performance and handling than full length keel. Rudder on the aft end of the keel improves self-steering ability on some designs.

Cons: Under engine, this keel form has a large turning circle ahead and poor control astern. Since the rudder is not ‘balanced’, the helm on some designs can feel quite heavy.

Fin keel with skeg-hung rudder

The skeg gives protection to the rudder. Credit: Graham Snook/Yachting Monthly

Pros: The further reduction in wetted surface area leads to more boat speed. Directional stability and close-windedness are also improved. If full depth, the skeg can protect the rudder against collision damage.

Cons: When combined with a narrow stern, this keel format can induce rolling when sailing dead downwind in heavy winds.

Fin keel with separate spade rudder

Fin keel with spade: Low wetted surface and aerofoil shapes enhance performance. Credit: Graham Snook/Yachting Monthly

Pros: The fin and spade rudder mix reduces wetted surface and gives a more sensitive helm – especially if the blade has ‘balance’ incorporated in its leading edge. Handling under power in astern is precise and the turning circle is small.

Cons: The rudder is fully exposed to collisions. There are no fittings connecting the rudder to a keel or skeg, so the rudder stock and bearings need to be very robust.

Shallow stub keel with internal centreplate.

Pros: When lowered, the plate gives good windward performance. The plate can act as an echo sounder in protected shallow water. There is normally no internal centreplate box to disrupt accommodation. With the plate raised, off-wind performance is good.

Cons: The plate lifting wire needs regular inspection and occasional replacement. Windward performance with the plate raised is poor.

Lifting or swing keel

Boats with lifting keels tend to surf earlier downwind. Credit: Graham Snook/Yachting Monthly

Pros: Shallowest draught so more cruising options; can also be moored on cheaper moorings. Surfs early downwind. Small wetted surface so can be fast.

Cons: Reduced living space due to internal keel box. With a raised keel, poor directional control. Susceptible to hull damage if grounding on hard material.

Twin or bilge keel

Bilge- or twin-keelers can take the ground on the level. Credit: Graham Snook/Yachting Monthly

Pros: Can take the ground in a level position. Modern twin-keel designs with around 15º splay, around 2º toe-in and bulbed bases perform well upwind. Good directional stability due to the fins. Modern twin keels with bulbed bases lower the centre of gravity.

Cons: Older designs do not point upwind well. Slapping sound under windward keel when at a steep angle of heel on older designs. Antifouling between the keels can be tricky. Can be more expensive than fin keels.

Wing keel: A low centre of gravity gives a good righting moment. Credit: Graham Snook/Yachting Monthly

Pros: Low centre of gravity means good righting moment. Shallow draught. Sharper windward performance.

Cons: Larger surface area means it is more likely to pick up fishing gear, like lobster pots. Difficult to move once it is grounded. And difficult to scrub keel base when dried out alongside a wall.

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• The Fundamental Role of the Keel in Sailing Dynamics

In the world of sailing, the keel is more than just a structural component; it's the backbone of a sailboat's stability and performance. This guide delves into the keel's essential role, its various types, and how it influences sailing efficiency and safety. Whether you're a seasoned sailor or new to the nautical scene, understanding the keel's function is crucial for appreciating the intricate balance of sailing.

Understanding the Keel

At its core, the keel is a structure that extends along the bottom of a boat, serving multiple vital functions from stability to movement control.

What is a Keel?

A keel is the longitudinal structure found at the base of a boat, extending into the water. It provides stability, prevents sideways drift (leeway), and houses the vessel's ballast, keeping it upright and balanced.

The Evolution of the Keel

Historically, keels were simple structures. However, with advancements in naval architecture, keels have evolved into complex designs, each tailored to specific sailing needs and water conditions.

Read more articles about sailing, sailing tips and destinations in our  Magazine .  

Types of Keels and Their Impact on Sailing

Keels come in various shapes and sizes, each with unique characteristics that affect a boat's handling, speed, and safety.

Fin Keels and Bulb Keels

Fin Keels : Known for their deep draft and minimal horizontal area, fin keels offer excellent upwind performance.

Bulb Keels : Feature a bulb at the bottom to lower the center of gravity, enhancing stability without significantly increasing draft.

Full Keels and Wing Keels

Full Keels : Run almost the length of the boat, offering unmatched stability and protection for the rudder but at the cost of speed and maneuverability.

Wing Keels : Designed to improve performance in shallow waters, wing keels feature horizontal projections that act like wings, reducing draft and enhancing stability.

The Keel's Contribution to Sailboat Performance

The keel's design directly influences a sailboat's performance, from how it slices through water to how it handles in various weather conditions.

Stability and Balance

The keel helps to counterbalance the force of the wind on the sails, allowing the boat to remain upright and stable, even in rough conditions.

Maneuverability and Speed

The shape and size of the keel affect how easily a boat can turn and its overall speed. Advanced keel designs aim to optimize these aspects without compromising safety or stability.

The keel is a testament to the sophistication and evolution of boat design, playing a pivotal role in the safety, stability, and performance of sailboats. By understanding the different types of keels and their functions, sailors can better appreciate the intricate dance between vessel, wind, and water, leading to more informed choices and enhanced sailing experiences.

So  what are you waiting for?  Take a look  at our  range of charter boats  and head to some of our  favourite  sailing  destinations .  

I will be happy to help you with your boat selection, please contact me.

Denisa Kliner Nguyenová

What’s Behind Different Keel Configurations by Jim Schmicker

In recent years, the superyacht market has become more focused on greater performance by optimizing all aspects of a yacht’s design, engineering and construction. 

The choice of the keel configuration is surely one of them. 

It’s not surprising that the first three units of the brand new SW105 miniseries will each have unique keel designs to satisfy the requirements of three different owners.

To his end, we’ve asked Jim Schmicker, Vice President of Farr Yacht Design, one of the world’s foremost designer of racing and cruising sailboats, to explain how the choice of the keel design has specific benefits that make it the best choice for a particular owner’s needs.

Jim Schmicker Is Vice President and shareholder of Farr Yacht Design. The company is recognized as one of the world’s foremost racing yacht design studio, based on one of the most impressive winning results records ever compiled by a single company. For more than 30 years, FYD has been developing fast, custom and production cruising yachts. Southern Wind has collaborated with this reputable studio since 1992.

KEEL DESCRIPTIONS

When approaching the cholce of a keel, an owner should be aware that each of the options has advantages and disadvantages but all of them are designed to deliver excellent performance and achieve stringent stability targets while maintaining a similar displacement.

The simplest keel option for construction and installed systems is the fixed keel. The choice of draft for a fixed keel Is decided by balancing upwind performance against reasonable access to ports and anchorages. Reaching and downwind performance is the strongest feature of the fixed keel so long as sufficient stability is achieved. The keel is fabricated out of mild steel plates that are formed and rolled into the correct shape. Considering cost, portions of the keel, such as the leading and trailing edges of the fin, can be CNC machined and the rest hand-faired or the entire keel can be machined. This construction method results in a simple and light structure. Given the shallower draft compared to lifting or telescopic keels a heavier bulb Is necessary to achieve the target righting moment. However, the light fin construction helps to mitigate some of the relatively greater bulb weight. Attachment to the hull is entirely below the cabin sole which facilitates a variety of choices of interior layout with no constraints on either the accommodation or machinery spaces.

Fixed Keel showing Bolt Pattern and Internal Construction

LIFTING KEEL

The lifting keel is a popular choice for superyachts of this size. The ability to raise and lower the keel allows access to ports and anchorages with limited water depth while the deep maximum draft achieves excellent upwind performance. The keel construction is complicated with hydraulic cylinders housed internally to the keel, PLC systems, locking pins to hold the keel In the raised position and adjustable bearing pads to ensure tight tolerances and no movement of the keel In Its trunk while underway. The high number of moving parts and complex hydraulic control systems have associated installation and maintenance costs. The keel trunk takes up significant space In the accommodation but with clever integration with other aspects of the interior its impact can be diminished. The keel is typically constructed out of high strength carbon steel plates welded together and CNC machined to an extremely high level of accuracy. As such, advanced foil sections can be used which results in higher lift to drag ratios being achieved. The lower portion of the keel fin, below the hull in the raised position, is tapered to improve lift efficiency, optimising the amount of surface ares and reducing drag.

Lifting Keel with Tapered Lower Portion Showing Hydraulic Cylinders, Trunk and Bearing Pads

TELESCOPIC KEEL

The telescopic keel combines some of the benefits of the fixed keel and lifting keel. It achieves a similar amount of draft adjustment as the lifting keel with only minor intrusion into the interior. The upper, fixed part of this design is installed partly inside the hull but mostly outside and below the hull surface. The lower, moving part retracts into the upper part and incorporates a foil-shaped shell that slides over the outside of the upper part. Similar to the lifting keel, the telescopic keel is a complex installation with a high number of moving parts and hydraulic systems with associated costs. The fin is typically constructed out of high strength stainless steal plates welded together and CNC machined to an extremely high level of accuracy. The un-tapered planform shape required to house the hydraulic cylinders and structure supporting the lower part results in higher surface area, The fin components have a relatively higher weight and center of gravity.

Telescopic Keel with Un-tapered Lower Portion Showing Hydraulic Cylinders, Internal Structure and Shell

KEEL COMPARISON

Each of the keel designs has specific benefits that may make it the best choice for a particular owner’s needs. In terms of draft, both the lifting and telescopic keels achieve shallow draft (3.15m to 3.65m) without compromising performance as a result of their heavier fins and associated structure. The fixed keel requires an acceptable amount of draft (in this case 4.5 meters) for reasonable upwind performance while still allowing access to the owner’s preferred ports and anchorages. A fixed keel has a much lighter fin and associated structure weight. For the same displacement, it achieves the highest righting moment because the keel has the deepest center of gravity as a percentage of Its draft. A secondary benefit of the fixed keel Is less heeling moment because the sideforce it generates is acting closer to the surface of the water so the fixed keel version operates at a lower angle of heel.

The telescopic keel has the best combination of performance, harbor access and disruption of the interior. Its disadvantages are greater wetted surface, volume outside of the hull and maintenance costs. With specific reference to the Southern Wind SW105 project, because similar displacement was a design requirement, the performance differences between the first three units is not large. However, the deepest maximum draft (5.6m) of the telescopic keel produces the best upwind performance, as a result of its lower induced drag.

The lifting keel (at 5,15m draft) has the next best upwind performance while the fixed keel is strongest in power reaching conditions. For performance versus rating the lifting and fixed keel versions are essentially equivalent over a balanced race course with the advantage going to the lifting keel for more upwind-downwind oriented races and to the fixed keel when the reaching content Is greater. The telescopic keel, with its slightly less efficient keel shape, comes in a very close third place behind the other two options. The initial cost of the fixed keel is the least of the three and ongoing maintenance costs will be less than these of the lifting and telescopic options.

KEEL CHOICES FOR THE FIRST THREE SOUTHERN WIND 105’S

The Southern Wind 105 Is the newest addition to the SWS line of luxurious, performance, blue-water cruising superyachts. The first three yachts constructed will each have unique keel designs to satisfy the requirements of the three owners. The overall parameters of a superyacht of this size, the necessary draft for reasonable upwind performance and the owner’s requirements for keel draft for access to his preferred ports and anchorages have led to fixed, lifting or telescopic keels being viable options.

Design Brief

Desire for an advanced keel design with maximum upwind performance without any significant compromise to the interior layout and saloon space.

Best performance for both racing and cruising and no requirement for a specific minimum draft. The 4.5m draft is designed to achieve the low leeway angles desirable for racing combined with high sailing stability.

Best performance combined with a minimum draft requirement of 3.1m Is the strongest driver of the keel design. Intrusion into the interior is apparent but details of the trunk design allow light across the saloon and avoid a complete separation of the two sides of the yacht.

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Keel design: What’s best?

Posted by Ted Brewer | Boat Reviews

Ted Brewer reviews the ins and outs and ups and downs of keel design

The purpose of a keel, fin, or centerboard is to provide resistance to making leeway; in effect, to keep the yacht from sliding sideways through the water due to wind pressure on the sails. Various shapes of underwater plane have been in and out of style over the past 150 years.

The highly stylized shark fin has extreme rake and a sloping tip chord.

The basic full-keel shape had the longest run, as it was the standard for bluewater sailing craft from pre-Roman times to the earliest days of yachting. The deep, full keel was supplemented in the mid-1800s, for the shoalwater areas of Britain and North America, by centerboard craft. These cover such working types as the sharpies, Cape Cod catboats , and Chesapeake Bay oyster skiffs, to mention a few.

The first truly modern keel yacht, with a cutaway forefoot and highly raked rudder post, was designed by Capt. Nathanael Herreshoff with his Gloriana design of 1891. But it did not catch on for bluewater sailing. Until the late 1920s, the typical offshore yacht, whether cruiser or ocean racer, resembled a sailing fishing craft in the shape of its lateral plane: a long, full keel with deep forefoot and fairly vertical sternpost. Such a shape has the benefits of good directional stability, ease of steering, and the ability to heave to in heavy weather, all desirable traits for a boat. However, its faults may include slowness in stays, excess wetted surface making it slower in all types of air and an inefficient lateral plane shape that has excess leeway, considering its relatively large area. Typical small yachts of this type are seen today in the Colin Archer types and the Tahiti ketch and its copies, while replicas of traditional sailing craft such as Bristol Channel Cutters, Friendship sloops, fishing and pilot schooners, and similar lovely vessels still appear in our waters. Fortunately, many of these workboat types have been developed to the point where the ills of the true full keel have been greatly reduced. Then the result is a handsome cruiser that sails quite well and attracts a great deal of attention wherever she drops her hook.

Successful Sailboat Keel Types

The cutaway keel was revived for ocean racing by Olin Stephens in the late 1920s, with his lovely yawl, Dorade, still sailing and winning classic yacht races more than 70 years after her launching. Her offshore racing successes finally proved that the full keel was not essential to seaworthiness, and it definitely detracted from speed and weatherliness. As a result of its improved performance and handiness, the “modified full keel” form caught on quickly once Dorade showed the way and became the standard for the next 35 years. This type of lateral plane is still sailing in many popular older designs such as the Albergs, the Folkboat, the Luders 33, the Whitby 42, and even some newer yachts.

The modified full-keel form features generally good handling and directional stability plus reduced wetted surface, compared to her true full-keel sister. The yachts can perform well in all conditions and, as they are generally of heavier displacement than contemporary ballasted-fin boats, they do not give away much in light air, despite the added wetted area. A yacht with a modified full keel can sail right up with the best of them if she is given sail area commensurate with her typically heavier displacement.

In my own work, I developed a modified full keel, with the rudder set aft and vertically in the contemporary fashion, in order to improve directional stability and handiness. Then, to reduce wetted area, the lateral plane is substantially cut away ahead of the rudder in what some have termed “the Brewer bite.” The Cabot 36 and Quickstep 24 of my design were early examples of this form. The size of the cutout depends to a large degree on how insistent my client is on having a “full keel,” and I try to make the cutout as large as I can decently get away with. I don’t claim to have originated the shape, though, as the late L. Francis Herreshoff used a not dissimilar profile many years earlier in the design of the lovely 57-foot ketch, Bounty.

Taken to Extremes

Like all good things, the modified full keel was cut away more and more for bluewater and inshore racers in an attempt to reduce wetted area until, finally, some designers took it to extremes. This reduced directional stability and produced craft that were almost impossible to steer in breezy conditions, broaching with monotonous regularity. I can recall working on the design of many short-keel 5.5-Meter yachts in the 1960s, and we always said they were three-man boats with six-man spinnakers! It’s hard to believe none of them were knocked down and sunk, as they were extremely difficult to control on a reach or run, and the hulls were pure leadmines, with 3,500 pounds of ballast in their very short keel and only 1,000 pounds of wood and rig above it!

Olin Stephen’s genius began another fad in the mid 1950s, the keel-centerboard design. After Finisterre showed the way, keel-centerboard yawls were built in sizes from 24-foot midget ocean racers, to the largest offshore yachts, in order to take advantage of favorable ratings under the CCA rule and emulate Finisterre’s record of wins. The keel-centerboard hull has gone out of fashion now, but the type still has merit where a stable, beamy, shoal-draft yacht is desired with little sacrifice of weatherliness or seaworthiness. Indeed, the Bill Tripp-designed Block Island 40 and Bermuda 40 are keel-centerboard ocean racers from the old school and have been in production for more than 30 years now. These classic yachts have made many long ocean voyages, including several world circumnavigations and are first-class bluewater cruisers in every respect.

Keel Types Here to Stay

A rather squared-off fin, not unlike the Cal 40 keel.

The fin shape is not new either, as ballasted fin yachts were pioneered by Herreshoff at the turn of the century for inshore racing. Then, due to excesses and bad design, the shape died out, except for a few one-design classes, until Bill Lapworth dropped a bomb on the ocean-racing scene in the mid-1960s with his Cal 40 design. The Cal 40s made believers out of many yachtsmen who could not believe that a ballasted-fin/spade-rudder yacht was a serious bluewater ocean racer. After wins in the Trans-Pac, many East Coast races, and the 1966 Bermuda Race, it became evident that the fin was here to stay for ocean-going and coastal cruising yachts. Please note that I do not use the term “fin keel” anymore, as I feel it is a misnomer. The keel is the structural backbone of the vessel, and the fin hangs from it. Fish have both backbones and fins; so do yachts.

A less extreme fin keel, with a more parallel tip.

A well-designed fin, in conjunction with a skeg-hung rudder, can provide excellent directional stability, handiness, reduced wetted area and improved weatherliness. The fin/spade rudder combination reduces wetted surface even more. It may have a little (or a lot) more sensitive helm than a fin/skeg rudder yacht, but it has one big advantage over it and all other forms of lateral plane: it can be steered in reverse under power. This can make life a great deal easier in today’s crowded marinas, as many have discovered.

These are some of the reasons that we see fins on the great majority of our new yachts today; they are not simply a fad. There are good fins and bad fins, of course, and it is not always easy to tell them apart. The shape of fins over the years has been limited only by the designer’s imagination. Fins have been set at every angle from the vertical to highly raked aft. They have been deep and narrow, shoal and long, resembling a shark’s fin or whale’s tail, or boxy fins similar to the original Cal 40 design.

A contemporary bulb fin with winglets.

Major Problem

A very deep, narrow fin can be a problem to haul on a marine railway, so the cruising skipper should consider haulout ease when boat shopping. A crane or travel lift is the best method for hauling yachts with extreme fins, but may not always be available in out-of-the-way areas. There is also the danger of damage to the shaft or strut if slings are improperly positioned. Still, the major problem of the high-aspect-ratio fin is structural strength, as it can impose extreme loads at the point of attachment to the keel. Indeed, some years ago I was an “expert witness” in a court case concerning three men who drowned when their yacht sank as a result of its fin tearing off when the vessel ran aground.

The cruising skipper would do well to avoid yachts with extreme fins, both for considerations of haulout ease and structural strength. Fortunately, the heavier, deeper hull and generally shoaler draft of the typical cruising yacht mean there is less height available between the bottom of the hull and the point of maximum draft. So, a longer, lower-aspect-ratio fin is the only solution. On the other hand, the racing sailor will want a fin with an aspect ratio as high as the draft rule will allow. Such a fin is more efficient per square foot, so the area can be smaller and the wetted surface reduced. In Aero-Hydrodynamics of Sailing, C.A. Marchaj recommends about 4 percent of the sail area as a good guide for fin area, and I feel the cruiser should err on the high side, as a small increase in resistance is preferable to increased leeway. On the other hand, I have used as low as 1.75 percent area with good results on an extreme racer with a fin of 2.75 aspect ratio.

Sailboat Keel Aspect Ratios

This “aspect ratio” is the ratio of the span (depth) squared to the fin area; that is, my extreme fin had an 11-foot span and 44 square feet of area, so its aspect ratio was 121/44, or 2.75. If it had a 4-foot span with 44 square feet of area, not uncommon proportions for a cruising yacht, its aspect ratio would be 16/44, or a low 0.3636.

The aspect ratio can also be described as the span divided by the mean chord, the average fore-and-aft length of the fin, and this gives the same result.

A large part of the resistance of a keel is created by the vortices, similar to miniature whirlpools that form when the water flows across the bottom of the keel from the high-pressure (leeward) side to the low-pressure (windward) side. It requires energy to form those vortices and that energy is then not available to propel the boat forward. Obviously, the shorter the keel or fin tip, the smaller and weaker those vortices will be, and that translates to reduced resistance. This is one reason that racing yachts usually feature high-aspect-ratio fins with short tip chords.

However, the formation of vortices can be greatly reduced by using end plates, or wings, to change the flow direction and eliminate crossflow. My own preference, for a fin of average span, is for an end plate that is but a few inches wider than the maximum width of the fin bottom. We tested an actual yacht with such an end plate on one side only and noted a substantial improvement in performance when she was heeled so that the end plate was on the leeward side. Where the draft is shoal and the fin span is on the small side, then a wider end plate, or even a wing, might prove beneficial. However, a wide wing can be a structural weakness, particularly if the boat goes hard aground and has to be towed off, or pounds on the rocks for any length of time.

Sweepback Angles

In the 1970s, I saw more than one very-high-aspect-ratio fin with tremendous sweepback angle. This certainly gives an impression of speed but, as Marchaj pointed out, tank tests have shown that the sweepback angle can be related to the aspect ratio: the higher the aspect ratio, the more vertical the fin should be. Indeed, the very-high-aspect-ratio fin on my BOC racer was set absolutely plumb until a hard grounding set the tip back a quarter inch or so, the result of taking a yacht with a 13-foot draft through a channel dredged to 11 feet! Most cruising-yacht fins are of low aspect ratio, of course, so should have substantial sweepback, up to 57 degrees, with an aspect ratio of 0.5, according to Marchaj. Although most designers try, it is unfortunate that obtaining the perfect sweepback angle is secondary to locating the fin to balance the sailplan, as well as fitting the ballast at the correct spot for proper fore and aft trim. The taper ratio (tip chord length/root chord length) also deserves consideration. Tests on one series of fins showed that a fin with 0.32 taper ratio was 1 percent more efficient than an untapered fin and had very slightly less resistance. This is a small difference but cannot be ignored by the racing skipper. Again, the reduction in drag may be due to reduced vortices from the shorter tip chord. Marchaj also states that the taper ratio should be reduced as the sweepback angle increases. However, the very-low-taper-ratio fins may not be the best solution for a cruising yacht. The tip chord should be long enough so the vessel can be hauled on a marine railway with no major problems. Too, on a moderate-draft cruising yacht, a short tip chord forces the ballast higher, so stability can suffer.

Lower Ballast

Another consideration in the fin profile is whether the tip chord is sloped down aft or parallel to the waterline. The parallel tip chord makes good sense. It allows the ballast to be lower for added stability, it eases blocking up the boat when hauling and, fortunately, tests have shown that it is also superior to the sloped tip chord in other ways. Having the aft edge of the tip chord deeper than the leading edge has no practical effect on aspect ratio, and such a fin develops less lift and more drag than one with a parallel tip.

The National Advisory Committee for Aeronautics (NACA) tested a large variety of streamlined shapes for lift and resistance and the information on these is available in a book, Theory of Wing Sections, by Abbot and Von Doenhoff. These are the shapes that designers refer to when they say their new magic fin has an NACA section. Generally, the shape selected will be similar to NACA 0010-34 or 0010-64 series. The leading edge will be elliptical, as a blunted nose increases resistance while a pointed leading edge promotes stalling. The maximum width will be about 40 to 50 percent aft, and the shape will be streamlined to a fairly sharp (but not razor-sharp) trailing edge. The thickness ratio will be 0.8 to 0.12 of the chord length, although this may be increased to 0.15 to 0.16 at the tip chord. There are advantages to having an increase in thickness ratio at the tip chord, including being able to fit the ballast lower. This need not mean that the fin is bulbed, though. For example, a fin that is 8 feet long at the root and 5 feet long at the tip may have a 0.10 thickness (0.8 feet) at the root and 0.15 thickness (0.75 feet) at the tip. The fin is still slightly thinner at the bottom than at the top, but the thickness ratio has increased.

Increased Resistance

It is not uncommon to see fins wider than 10 to 12 percent of their length, as the designer may need to fatten the fin in order to locate the ballast in the correct spot for proper trim. Very shoal-draft boats may require fatter keels or fins in order to get the ballast as low as possible for stability. Still, extra width does increase resistance so there is a tradeoff; added stability increases performance while a thicker fin reduces performance. Thirty-five years ago, when I worked for Bill Luders, we tank-tested dozens of 5.5-Meter models. These very short-keeled 30-foot sloops had a minimum keel width of 4 inches under the rule, and whenever we tried a model with a wider keel in order to get the ballast lower, we found that overall performance suffered.

We also tested a number of bulb keels on the 5.5 models but they never proved out in the tank, either, although several different shapes were tried. Then, in the late 1970s, I tank-tested the model of the new Morgan 38 at Stevens Institute, first with a fairly fat NACA fin in order to maintain the desired 5-foot draft, and then with a patented bulb fin that we let its designer draw up, with no stipulation on draft. The bulb saved only 2 inches of draft but showed so poorly against the NACA fin that the 38 was put into production with the more conventional shape.

The tip shape, viewed from ahead, may be flat, round, elliptical, or bulbed. Tests show that the flat, squared-off tip develops a bit more lift to windward and that the round or elliptical tip has less drag on a run. The differences are slight but, today, I favor the squared-off tip with an end plate for yachts of average draft. A vee tip was tried in the 1960s on a few yachts, but never became popular. Bulbs and wings, often in combination, are fairly common on contemporary production boats. Usually, they are an attempt to produce a very shoal-draft yacht for use in waters where the bottom is close to the top and, in those cases, they may make sense.

There is a never-ending variety of fin shapes and, to be honest, I’m not sure which is best. Generally, I prefer a fin similar to the old Cal 40, a little shorter perhaps, and fitted with an end plate. Such a fin provides a desirable combination of good performance, ease of haulout, and structural strength, all very important factors for the cruising skipper.

Article first appeared Good Old Boat magazine: Volume 3, Number 4, July/August 2000 .

About The Author

Ted Brewer is one of North America's best-known yacht designers, having worked on the America's Cup boats, American Eagle and Weatherly, as well as boats that won the Olympics, the Gold Cup, and dozens of celebrated ocean races. He also is the man who designed scores of good old boats, the ones still sailing after all these years.

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A Quest for Keel Integrity

Recent tragedies at sea highlight structural shortfalls..

Over the past few years, weve noticed a worldwide uptick in keel failures. The problem has yet to reach epidemic proportions, but we are hearing more and more troubling accounts of what happens when the ballast parts company with the hull, and a crew faces capsize, flooding, and-all too often-death.

The number of incidents speaks for itself. When the International Sailing Federation (ISAF) formed a working group in 2013 to look into the keel loss issue, it tallied up 72 incidents (since 1984) that resulted in 24 deaths. Far from complete, this profile records only incidents where survivor reports or vetted secondhand accounts were available, or where vessel remains pinpointed keel failure as the cause of a loss. No numbers exist for cases in which sailboats simply disappeared at sea. Keel failure, resulting in major hull damage and loss of stability, certainly can’t be ruled out in those cases.

Photos by Ralph Naranjo

Its often hard to come by detailed information portraying what actually went wrong due to litigation and the regular use of gag orders that hold back the details and protect certain parties involved in the litigation. The much larger automotive and aviation industries attract more scrutiny and regulatory control, and product failures gather greater attention. But when it comes to keel failures, mums the word. So whos keeping track?

In the U.S., theres a long list of players who have a role in determining how well (or poorly) recreational boats are built. Theres the National Marine Manufacturers Association (NMMA), American Bureau of Shipping (ABS), American Boat and Yacht Council (ABYC), the American Boat Builders and Repairers Association (ABBRA), the Society of Naval Architects and Marine Engineers (SNAME), several marine surveyor organizations, and the U.S. Coast Guard, just to name a few. And to the credit of many of these august institutions, the topic of sailboat keels has not been ignored. However, in contrast to the Europeans effort to define keel attachment scan’tlings via ISO 12215-9, theres no apparent rush in the U.S. to better define structural standards for keel attachment. The ABS published the 1994 Guidelines for Offshore Racing Yachts, which incorporated some valuable specs defining scan’tlings (the dimensions for structural components) and engineering approaches for attaching the ballast to the hull. For example, where keel bolts penetrate the keel stub or canoe body of the hull, the laminate should be a minimum thickness equal to the diameter of the keel bolt. Even to the casual observer, this specification hardly seems adequate, especially in light of the radical, long bulb keels we see today. As it turns out, many of the recent keel failures reveal hull and keel stub laminates that fail to meet the 1994 ABS guidelines for thickness. How did these boats even make it onto the market?

From Paper to Production

Every naval architect quickly learns the peril of what can happen when a completed boat bears little structural resemblance to the boat he or she designed. Due to the nature of the boatbuilding business, design specifications often vary from the finished product specs. Seldom is a change for the better.

In the past, the naval architect or yacht designer was closely involved in the production of his design, often presiding in the boatyard during the building process. Those days, unfortunately, are long gone. It is only natural to wonder who oversees how the vessel is built today, and how the devils details are excised.

Currently, its not unusual for a boat builder to purchase the plans of a favored design and then take over the development with their own rendition of engineering specs. Vital issues such as the laminate schedule, which varies throughout the boat, must be applied according to engineering specs during the molding process. Loads vary in different parts of the boat, and structures that support the ballast keel must handle huge bending moments coaxed by wind, wave, and gravity. Top-quality builders carefully monitor the unit count of fiber reinforcement and resin volume used, pay heed to minimizing void content, check cure time and temperature, and confirm resin hardness. Some builders hire composite engineering firms that will gladly provide laminate plans that identify the specific fiber type, number of layers, core material, and resin used in specific regions of the boat. Most hull and reinforcing grids are built in female molds and later bonded together. The composite experts are often on hand to make sure that all goes as planned and that the secondary bond joining these components is as void free as possible.

But building shortfalls do happen. In one case, a new, 44-foot Tartan sloop was beating to windward as the cabin started to fill with seawater. The boat had started to split down the middle, the result of the builders laminating crew deciding to use a butt joint at the centerline rather than overlapping each layer of fiberglass.

A 36-foot boat serviced by PS Technical Editor Ralph Naranjo at the boatyard he used to manage clearly illustrated the problem with contemporary keels. The boat had a deep keel sump and bolt-on external ballast. Just out of curiosity, Naranjo had the travelift operator step down, and with the vessels keel suspended a few inches above the ground, the operator and Naranjo took turns putting pressure on the end of the keel with their feet. Immediately, the suspended, lead-ballast keel began to move back and forth. This minor can’ting caused the hull to dimple with each sway. The owner agreed with Naranjos suggestion that they add transverse framing in the sump and more laminate at the turn of the bilge.

Sailboat design has evolved over the years, and higher performance underbody configurations are definitely playing a role in many of the keel calamities we hear about. A few decades ago, a sailboats keel was designed to be contiguous with the hull, and the ballast could be external (bolted on) or internal (encapsulated in a keel/hull monocoque structure). The interface between the ballast and the hull extended fore and aft for a greater distance than its root-to-tip measurement.

Today, many race boats and performance cruisers incorporate a very different design paradigm. One of the contributing factors in keel vulnerability is that modern keel designs are like a lever that keeps attempting to split the hull in two. Naval architects responding to a demand for better upwind performance have turned to keel shapes that are optimized for lift and righting moment, making them look like tongue depressors with a bulb of lead at their base.

The big challenge lies in how to attach such a lever-like appendage to the hull and to transfer the loads away from the point where the fin root meets the hulls canoe underbody. The good news is that it can be done. The bad news is that the best material to use is the proverbial unobtainium-a strong, stiff, light, isotropic fiber-rich polymer that has yet to be invented. So the next best alternative is a tapered, grid-like reinforcement near where the keel meets the hull.

In the area where the keel meets the hull, skin thickness is increased, core is left out, and stiffness is achieved through the addition of internal structure. Any effort to save further weight in this region is like putting less carbon-dioxide in a fire extinguisher so it will be a little lighter. Somewhere along the way, boatbuilders and designers seem to have lost sight of the fact that this is the part of a boat where structural overkill is totally acceptable.

The quest to make racing sailboats lighter and stiffer has resulted in more and more of the laminate ending up as grid or other longitudinal and transverse support rather than hull skin. The net result is a thinner-skinned shell and a more rigid skeleton.

This paradigm was tried decades ago by the Kiwis and Australians who designed and built thin-skin, wood/epoxy hulls and stiffened them with aluminum-tube geometric shapes running fore and aft and linking to points where the keel, maststep, and chainplate loads were focused.

New Zealand designer Paul Whiting, a pioneer of ultralight, thin-skin racing sailboats, was lost at sea during a Sydney Hobart race when a Tasman Sea storm presumedly caused massive structural damage to his sloop Smackwater Jack. Similar hull failures occurred aboard around-the-world racing boats, and these data points led designers to reconsider scan’tlings and develop a better feel for how the dynamic impacts of a seaway influence structural decisionmaking.

Today, finite element analysis (FEA) and engineering software help guide designers. These new analytical tools allow boat designers to specifically locate the hotspots where the tug-of-war between righting moment and heeling moment act out their battle. Variables like wave impacts and sudden gusts can be modeled, but unlike the aviation industry, which does a superb job of keeping wings attached to aircraft, sailboats all too often develop keel woes. However, as a naval architect recently reminded us, most pilots arent running their wing tips into mountain peaks, and there are no sandbars in the sky. In other words, the sailboat-building industry is under-estimating the net effect of running aground.

The Engineers Perspective

Philosophers and engineers have an affinity for first principles reasoning. In lay terms, this means drilling down to the fundamental reasons why something holds together physically or how reasoned thought springs from observable fact. When it comes to keels, the engineers first principles focus on using numbers to define stress and geometry to show how forces impact structure. The engineers goal is to be able to quantify the energy transferred through the hull, rig, and appendages, and to respond to the empirical data with structures that can handle the load.

When it comes to external-ballast keels, there are several points where key connections are made. The ballast itself is usually lead or iron, and mechanical fasteners are used to secure it to the hull. Or ballast may be attached to a keel stub or blade-like foil before being attached to the hull.

Keels with higher aspect ratios (depth to length) and longer lever arms focus more force on the surface area of this critical junction. The person doing the engineering must juggle multiple factors at once. The ballast weight, the distance of the ballasts center of gravity from the critical keel-to-hull joint, the laminate schedule, the reinforcing structure, and the mode of fastening make it a multivariate challenge.

Lets start with the question of ballast material and its role in keeping the keel attached to the boat. Lead is still the ballast material of choice because of its density and the relative ease with which it can be cast into a hydro-

dynamic shape. But a few builders and boat owners have learned the hard way that pure lead is too malleable and may even allow keel bolts to pull free. Consequently, foundries that make keels have perfected an alloying process that involves adding a small amount of antimony (about 4 percent) to the lead to make it less malleable and more willing to hold both keel bolts and its shape.

Monel is the best metal to use for keel bolts due to its strength and corrosion resistance, but it is cost is prohibitive, so 316 stainless steel or even silicone bronze are good alternatives. It makes good engineering sense to offset keel bolts rather than run them down the centerline. The working rule of thumb is to keep the outer wall of a keel bolt at least an inch under the lead surface and far enough down in the ballast to prevent it from being pried from the ballast.

Care must be taken when casting a keel to make sure that the keel bolts, and any weldment used to hold them in place, are preheated prior to the pour so that theres no chance of bubbling around the colder metal. These bubbles become voids than can trap water and cause corrosion problems. Thanks to good quality control at keel-casting companies, failures caused by keel bolts pulling out of cast lead are less prevalent today.

Keel-bolt metallurgy is another factor, and its a two-part story. Part one is all about the tensile strength of the material and what kind of out-of-the-box safety margin the bolts will deliver. The second part is about lifespan and corrosion resistance.

Every time a sailboat tacks or rolls in a seaway, keel-bolt loads swap from side to side. This on/off, tension-fatigue cycling causes changes in the metal at a molecular level, and some alloys are better than others at handling this type of cyclical loading. Of equal importance is the manner in which the ballast and hull surfaces mate. Imperfections in how the two surfaces make contact will result in uneven loading and even a perceptible wobble in the joint as gravity pulls the ballast from one side to the other. Simply filling minor voids between the keel and hull stub with a sealant is a big mistake. In cases where the surface-to-surface contact is imprecise, a high-density epoxy-filler repair should be carried out so that surfaces are both smooth and fit together precisely. (See PS Advisor, January 2008.)

Many production-boat builders opt for iron ballast and galvanized, high-carbon steel keel bolts. This is a cost-saving shortcut that, down the road, leaves an owner coping with rusting ballast and the ticking time-bomb of corroding keel bolts. Those buying a decade-plus-old, pre-owned sailboat with high-carbon steel keel bolts and iron ballast should consider having a good boatyard lower the ballast and carefully inspect the bolts. Simply torquing up the fasteners and heading off on a long ocean passage on a boat of this vintage is courting an unnecessary risk.

Some rust on keel bolts is to be expected, but how much is acceptable depends on how oversized the bolts are, how many hold the keel to the hull, and how long and wide the ballast-to-hull seam happens to be. Stainless-steel keel bolts arent totally immune to seawater chemistry, but high-nickel-content 316 stainless steel has a fine track record, as do silicone bronze keel bolts, keeping in mind that silicone bronze bolts must be slightly larger in diameter to deliver the same tensile strength.

Theres one keel usage where rust-prone carbon steel is gaining ground and its use makes sense. Its in radical race-boat fin/bulb keels where stiffness counts and deeper, thinner, shorter chord foils are the trend. In such situations, carbon fibers lighter weight isn’t a big advantage and high-tensile steels stiffness combined with its hardness and toughness are ideal for making mechanical junctions at each end of the foil. Slots in ballast bulbs and carefully engineered keel boxes built into the hull are costly, esoteric parts of many modern race boats. During the design process, much care is given to spreading the loads focused on these socket-like fixtures, and energy moves transversely across the hull and forward and aft via a network of frames and stringers.

Most production boats have a simpler solution for handling keel-bolt loads. In the era of wooden boats, floor frames and the keelson did a lot to dissipate ballast loads. Fiberglass changed some of the engineering. In the 1960s, solid fiberglass-reinforced plastic (FRP) laminate hulls with thickly laid-up keel sumps could easily cope with the loads from the long, shallow, ballast keel common for that era. As laminates grew thinner, core material spread throughout the hull and keels grew deeper but shorter fore-and-aft, attachment problems proliferated. Better engineering was on hand to offer solutions.

The modifications included keeping core material away from the critical interface where the ballast keel or keel stub met the hull. Another change was the introduction of grid structure to stiffen the hull so that it would reduce the bending moment induced by the keel. Cruisers were happy with the belt-and-suspenders approach of a thick hull skin and a strong grid. This increased the safety factor when it came to how well a keel was attached.

Racers, however, wanted a stiffer, lighter hull, but at the same time, they recognized that in order to win, one had to finish the race-which, of course, required keeping the keel and hull intact. Over the years, builders and designers have seen a proliferation of cautionary tales of what happens when this quest for a fast, light boat overshadows the sanctity of the keel-hull joint.

A key design consideration is the load imposed on the hull in a knockdown, when the mast is parallel to the water. In a knockdown, the loads at the point where the hull and keel meet skyrocket, especially when theres a bulb of lead at the other end and a very small area where the keel meets the hull. If the sailboat has been carefully engineered, the designer has calculated what this peak load will be and then chosen a healthy safety factor to hedge his or her bet. This safety factor will go a long way in accounting for some material deterioration due to minor corrosion, fatigue, or some other unforeseen situations.

The bible for many naval architects and sailboat designers is The Principles of Yacht Design (PYD) by Lars Larsson and Rolf Eliasson. And when it comes to the crucial links in keeping the ballast attached, the authors justifiably put much stock in hedging a bet. When it comes to keel-bolt diameter and floor-bending moment, they recommend a 5-to-1 safety margin. The less stringent ISO 12215-9 equations settle on a 2-to-1 safety factor for bending moment in category A and B vessels. But the wild card is not the sailing loads, which are quite definable; its the point loads linked to groundings and the ongoing weakening effect of cycle loading and corrosion.

The ABS guidelines mentioned earlier take a harder line when it comes to structure that mitigates grounding damage. It has the most stringent laminate thickness and core elimination requirements. Other classification scan’tlings diminish the projected loads of a grounding. They regard the inertial rotation of a hull as a means of significantly offsetting the stress of a grounding. The ISO guidelines, for example, take this into account. The result is a force of impact that is much lower than that envisioned by the ABS, which ignores the effect of inertial dampening during a grounding.

All this keel theory came into play two years ago, about 720 miles east-southeast of Nova Scotia, Canada, with the tragic loss of Cheeki Rafiki and all hands aboard. The incident occurred during a return passage to England from the Caribbean. The eight-year-old Beneteau 40.7 was in the charter trade as a race boat, and records revealed that it had been campaigned regularly in the United Kingdom during summers, in trans-Atlantic ARC races, and in Caribbean winter regattas between 2011 and 2014. On May 16, 2014, Cheeki Rafiki lost its keel and capsized in the cold North Atlantic; the life raft was apparently unable to be deployed. The Beneteaus upturned hull was later spotted by a merchant ship, and photographs revealed that some of the keel bolts, with nuts and washer plates in place, had pulled through the laminate and others had apparently snapped, leaving threaded rod, nuts, and washers behind.

According to the incident review done by the Marine Industry Accident Review Branch (MIARB), United Kingdom, the Farr-designed sloops had their structural details finalized by Beneteau. Beneteau indicated that the boat was designed to ISO A category standards and structural approval was made by Bureau Veritas. In the MIARB report, the University of South Hampton (Wolfson Unit) evaluated whether or not the Beneteau 40.7 would meet ISO 12215-9 criteria, which was not available when the boat was built. The reports conclusion was that the as designed parameters would meet the vast majority of structural requirements spelled out in the ISO 12215- 9 standard. However, according to the report, the keel washers did not meet the standard. Perhaps more tellingly, the standards did not allow for the elimination of a 24-millimeter keel bolt that should have been at the aft end of the keel.

The university report also commented on whether or not a change in grid stiffness caused by two previous repairs could have altered the grids load-spreading characteristics. In essence, investigators looked into whether or not a hard spot in the grid could have resulted in a stress riser that refocused loads and led to an area that was more prone to failure. Their finding was that the same FRP materials had been used in the repair, and it did not change the grids load-sharing characteristics.

Several things in the Cheeki Rafiki report stood out to us. First, its interesting to note the difference between the ABS minimum guidelines for skin thickness where keel bolts penetrate an FRP structure and the ISOs minimum. The ABS spec calls for a laminate thickness equal or greater than the diameter of the keel bolt. ISO guidelines call for a minimum of 9.1 millimeters. The Beneteau 40.7 had a hull skin thickness of 7.7 millimeters and made up for the shortfall by adding in the thickness of the stiffening structure, which was actually thicker than the hull itself (10.5 millimeters) but connected to the hull skin via a secondary bond. The total thickness, by this accounting, was 18.2 millimeters, but this is still less than the ABS minimum of 24 millimeters. Perhaps a thinner skin would be appropriate if the builder had been using a high-modulus, vacuum bagged, prepreg carbon-fiber laminate. (Prepreg laminate is pre-infused with resin to ensure a strong, lightweight laminate that has a high fiber content.) But the 40.7 was built using traditional wet layup, which results in a lower fiber content and a lower-strength laminate.

The report delves into Cheeki Rafiki s reported groundings and associated repairs. This section of the report leaves readers wondering whether ISO-compliant keels are too fragile. The ISO A categorization assumes correctly that all bets are off if you go and sail into the maw of a major hurricane, but should a relatively soft grounding render the hull a hazard?

The old Cal 40, Ericson 41, and plenty of 50-year-old Rhodes Bounty IIs still safely lug around their encapsulated-ballast keels. These designs have clearly stood the test of time. Well-designed and engineered, externally ballasted keels should be even more able to handle transverse and longitudinal loads, including the odd soft grounding.

One important consideration is the nature of the ISO ratings. PS has argued for years that the ISO rating is a standard meant to facilitate fair trade, not a benchmark for good design. Among the members of the ISO working group that came up with the standard were boatbuilders who had an interest in a broadly inclusive Category A standard.

In several instances, the standard for keels would prompt an engineer to question the rationale behind the rules. Take for example the fact that when it comes to keel attachment, the ISO 12215-9 specification lumps Category B and Category A vessels together. But when it comes to stability requirements, ISO recognizes that a Category A vessel will be exposed to more hazardous oceanic conditions, and therefore, will need greater stability. Why didnt the same seafaring logic prompt ISO to make the keel attachment scan’tlings for Category A sailboats more stringent than they are for Category B? Its not unreasonable to assume that ocean-crossing sailboats need higher keel attachment standards than boats designed primarily for coastal sailing.

Boat shows slips are brimming with production boats rated Category A, but does the label really mean they meet the challenge? Cheeki Rafiki was sailing in conditions well within the wind and sea state couched in Category A. The keel snapped off, and the crew perished. The Action to be Taken section in the MAIRB report includes a warning about minor groundings, painting the rudder day-glow red, placing the life raft in a spot that enables launching even if the hull is overturned, training the crew about capsize and inversion, and finally, it recommends that the ISO insert the text, in case of grounding, a full assessment/survey needs to be completed. We were surprised, if not shocked, to see that there was no mention of designing and building a stronger keel attachment, and no suggestion that the current scan’tlings for Category A vessels needed to be re-examined.

Older boats had a longer, wider keel-to-hull interface that permitted sailing (and grounding) loads to be spread over a greater area along the keel-to-hull joint. Many older boats carried internal ballast, eliminating keel bolts entirely. As long as the laminate in the garboard region and at the bottom of the hollow keel were thick enough, such structures were appropriate. However, in a grounding situation, external lead fairs better than fiberglass, as the soft metal absorbs the blows.

• The Cal 40 is a classic example of an early fin-keel design with internal lead ballast.
• Puffin is a classic, 47-foot, wooden Sparkman & Stephens yawl with supported external lead ballast and silicone bronze keel bolts.
• The two extremes of keel design are reflected in Hunter’s Child’s bulb and foil ballast and Itatae’s full-length, timber keel with internal lead ballast.

Good engineering starts with careful material choice and a clear understanding of the forces at play. Corrosion prevention is essential, and it takes a significant safety factor to protect keel bulbs from tensile, compressive, and torque loads linked to groundings.

• The thick, stainless-steel fin is slotted into a lead ballast bulb. Transverse bolts will lock the tenon-and-mortise joint, and a high-strength epoxy will be used to ensure a tight fit at the junction.
• Casting a lead/antimony, contiguous ballast keel with anvil eliminates the need for a fin-to-bulb connection.
• The larger the bulb and the finer the keel foil, the more load is placed on the fin-to-bulb junction.
• Large surface area, heavy, tip-of-the-keel ballast packages can be problematic in a grounding. If a tow boat attempts to spin the bow, keel damage may occur at the keel-to-hull interface.

Mechanically fastening a keel to the hull should be done with longevity in mind. Most bilges are wet, so corrosion-resistant metals are preferred. Monel and Aquamet 22 are superior to 316 stainless steel and are preferable where the interface between the ballast and the hull is small. Otherwise, a fair compromise is side-by-side, 316-grade keel bolts with backing plates installed over a thick, void-free, keel stub. Care must be taken to ensure internal grids are adequately bonded to the inside of the hull.

• American Bureau of Shipping guidelines call for the keel-stub base to be at least as thick as the diameter of a keel bolt.
• Here, carefully bonded transverse and longitudinal supports spread keel and mast step loads.
• Gaps between the keel and hull should be filled with high-density epoxy faired to create a complete face-to-face junction.
• Nuts should press down on thick backing plates. Galvanized, mild-steel plates are acceptable, but using non-ferrous metal for keel bolts and nuts is recommended.
• Some builders use steel weldments to spread loads at the keel bolts. These should be tapered, or extra laminate should be added to prevent stress risers where the metal ends.
• American Bureau of Shipping
• International Standards Organization
• Cheeki Rafiki Report

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What are the pros and cons of different keels?

We all sail for different reasons, in different cruising grounds and use our yachts differently, so it makes sense that there is no one-size-fits-all keel design. At Sirius, however, we like to make the perfect yacht for each individual owner. One of the ways we serve our customers is our choice of keels – at least six different options for each model. It’s one of the ways we stand out – or should that be stand up?

We offer three styles of keel: fin, twin and lifting swing keel. All of our keels excel in many ways, but every design does have drawbacks – this is not unique to Sirius, but the keel affects the way you use the boat, so it’s important to choose the right one for you.

These are the keels we currently offer:

Standard Fin (310 DS, 35 DS, 40 DS) Performance Fin (310 DS, 35 DS, 40 DS) Medium Fin (310 DS, 35 DS, 40 DS) Shallow Fin (310 DS) Shallow Twin (310 DS, 35 DS, 40 DS) Performance Twin (35 DS, 40 DS) Lifting Swing Keel (310 DS, 35 DS, 40 DS)

Does the choice of keel compromise ocean capability?

For Sirius yachts, absolutely not. It’s important to realise that choosing one keel style over the other does not affect the yacht’s righting moment or compromise its ocean-going capabilities at all!

Whichever keel you choose, deep or shallow, twin or fin, they all have the same stability. This is achieved by putting more weight in the bulbs of the shallower keels as the shorter lever can be balanced with higher weight. Most of the blue water cruising and circumnavigations in Sirius Yachts have been made with twin-keel or reduced/shallow fin keel yachts.

Does keel choice affect performance?

As our shallow keels are heavier the weight dampens the yachts’ motion at sea, but as a downside, you have more weight to move with sails or engine. Once you’re moving there isn’t a difference but when tacking or gybing, or when not steered well, you will lose a bit in sailing performance. The shallower draught yachts also lose a few degrees to windward compared to their deeper keeled sisters, but they are still good all-round performers. Our customers with racing backgrounds always try to go for a keel as deep and light as their sailing area permits, either with a single or twin keel.

Pros and cons of fin keels

The standard keel on our yachts is a fin keel. Most sailing boats today use a fin keel because it gives a good all-round performance on all points of sail. By keeping the ballast lower it gives the most comfortable motion. The main downsides are that the draught (the depth of water required to stay afloat) is the greatest, and it’s very important to avoid running aground on a falling tide. Fin keel boats cannot dry out without additional support, either from a harbour wall or by fitting a pair of beaching legs. Some fin keel yachts are not built strongly enough to stand on their keels when out of the water, so they can’t dry out alongside a harbour wall and they need to be kept in a special cradle when stored ashore to avoid the risk of the hull deforming under its own weight. By contrast, all Sirius yachts can stand on their keels for any length of time with no problem at all.

We offer four types of fin keel. The standard fin is available on the 310 DS, 35 DS and 40 DS and is fully cast-iron. It offers the best value, good performance, and excellent responsiveness. It is the deepest of our fixed-keel options, so if you want less draught you may want to look at our other fin keels.

We also offer a performance fin keel for all our models. This uses a cast iron fin with a lead bulb at the tip (bottom). The structural strength of cast iron means the fin is the slimmest profile, but lead is denser than iron so the same volume of lead will weigh around 1.4 times more than cast iron, giving more righting moment. The heavier, softer lead down low has less volume in the bulb so achieves a slimmer profile with less drag and therefore better performance.

A lead bulb is also safer if it hits something. Lead can absorb 60% of the energy in flexing and deformation so that only 40% of the force will be transferred to the laminated structure of the keel reinforcement. A lead bulb is very forgiving and easy to reshape and will not start to rust where the coating is damaged. We can use less volume of lead than iron, and achieve better stability than a wholly cast-iron keel. We can also reduce the depth of the keel and retain excellent stability. However, lead is more expensive than cast iron and the bulb must be attached very securely to the iron fin, so this option does cost more.

If you want less draught, we also offer a medium fin. This reduces the draught of the 310 DS and 35 DS by around 40cm/1ft 4in and 55cm/1ft 9in on the 40 DS. Like the performance fin, it uses a cast iron fin with a lead bulb. To retain the keel’s grip in the water it has to have a longer chord (the distance from fore to aft). While this gives the boat better directional stability, it does make her a little less responsive and a little slower to manoeuvre.

On our 310 DS, we offer a shallow fin option – a special version for very shallow cruising grounds. This fin keel offers the least draught of any of our fixed keel options at 1.15m/3ft 9in and draws 10cm/4in less than the twin keel version. The keel has a significantly longer chord (2.24m/7ft 4in compared to 0.7m/2ft 3in of the standard keel) so she has the reassuring directional stability of a long-keeled yacht but with better manoeuvrability.

Pros and cons of twin keels

Our twin keels are the most popular option. About 70-80% of all Sirius Yachts are delivered with them – and on the 40 DS it’s 90%. Some folk still believe there is a big performance penalty with twin keels. In the past this used to be true but it’s no longer the case with modern twin keel designs, from Sirius at least. We have conducted many two-boat comparison tests, often battling for hours, by ourselves, with owners, and for sailing magazines and we have found that there may only be one or two boat lengths of difference at the end of a long windward leg, if at all. At the end of many of these comparison tests, the crews could not point out which of the boats had the twin keel.

If you cruise tidal areas, twin keels will reward you time and time again. Not only do they give you a shallower draught than the typical fin keel, they also give you the ability to dry the yacht out, whether that’s for a motion-free night’s sleep, to explore cruising grounds others cannot reach, or just for cheaper mooring and maintenance costs.

We offer two styles of twin keels; performance and shallow draught. Both options have a cast iron fin with a lead bulb. The performance keels have a deeper draught and a thinner chord so they act and feel a bit livelier when sailing and manoeuvring. The shorter keels have a longer chord, but give you the ability to navigate shallower areas. Like all keel designs, twin keels do have some downsides. They are more expensive than fin keels, and when you’re sailing fast in choppy seas at a steep angle of heel, you can occasionally get a slapping sound when an air pocket is caught and pressed out under the windward fin. Lastly, we’ve yet to meet an owner who enjoys antifouling between the keels. Thankfully it only has to be done once a year and with twin keels you might get away with doing it less frequently. A twin keel yacht can be kept on a drying mooring, where fouling is reduced because the hull spends more time out of the water. And when you’re off cruising it’s easy to give the bottom a quick scrub while the yacht is dried out.

Our yachts will happily sit on their keels on a hard surface, like a drying grid, or for winter storage but on softer surfaces we use the rudder for additional support. The rudders on our twin keel yachts are specially reinforced for this: we use a Delrin sheave to take the weight of the hull and the tip of the rudder has a wide, foil-like foot to spread the weight.

A lifting swing keel

We are one of a few manufacturers to offer a lifting swing keel. There’s a lot of confusion with the term ‘lifting keel’, it seems to encompass all yachts that have centreboards, variable draught, lift-keels or swing keels. To us, a lifting keel boat should have all the ballasted weight of the boat in the keel, and that keel needs to be retracted into the hull.

Technically, a lifting keel is a keel that can be lifted or lowered and gives the boat the ability to dry out when the tide goes out. A lift-keel is a ballasted keel that raises and lowers vertically. A swing keel has a ballasted fin that has a single pivot point and the keel swings up into the boat. There are other variants of design, for example some have a lifting keel to reduce the draught of the vessel but they cannot dry out on it, others have a ballasted keel and ballasted grounding plate. All these examples have a keel that does two things: keep the boat upright and stop her sliding sideways. Our swing keel is designed with a NACA profile to give the most efficient performance.

Centreboard yachts have a centreplate to provide grip in the water and reduce leeway. The plate may carry only 15-20% of the ballast but the rest of the yacht’s ballast is within the hull and/or in the grounding plate. This is called an “integral keel” and is more common as it’s less complicated to build. The lower a yacht’s ballast is located, the better her stability, the more comfortable her motion and the better she stands up to her sail area. The most efficient place for the ballast is as low down on the deepest keel possible – this is why race boats have deep skinny keels with large torpedo-shaped bulbs on the bottom, but they don’t make practical cruising sailboats.

Our keel designs have more weight in the tip (bottom) – using a bulb on the fin and twin keel design and flaring the lower sections on our lifting swing keel yachts. You don’t have this with centreboard and integral keel yachts.

It might be surprising, but a lot of owners come to us thinking that a lifting swing keel is the best option for them. Sometimes it is, but about 98% of customers who approach us because we offer swing keels end up sailing away on a twin-keel Sirius.

The downsides of a lifting keel

A lifting swing keel does give you more cruising options. It will lift should you run into something and, of course, it gives you the shallowest draught. But that difference is only 40-50cm (1ft 4in to 1ft 8in) less draught than our shallow twin keel option. The lifting keel increases the complexity of the build and the final cost of the yacht; it also sometimes limits the internal layout and engine drive options, and you need to have twin rudders too. Twin rudders make the boat less manoeuvrable in a marina – you can opt for a third central rudder which does improve the handling, but again comes at an extra cost.

On the lifting swing keel, 40 and 310 owners are restricted to the use of a shaft drive, which is less efficient and you have to accept a bit more noise and vibration. When drying out, the drive is more vulnerable to damage, whereas it’s totally clear when taking the ground on twin keels. With twin keels, you also do not have to worry about something sticking out of the beach or stones lying around because the hull is high above the ground. With the hull up high, you do not have to dig a hole in the sand and slide down on your stomach to check or change your anodes as you would on a swing keel.

Sailors who are attracted to the idea of a lifting swing keel should carefully consider the pros and cons to compromise the least. When owners understand the repercussions of choosing a lifting keel yacht, many of them feel it restricts their options too much. They could have a lifting keel or they can sail with twin keels, dry out, have better close-quarters handling and save money in the process. Unless you need the shallowest possible draught – 0.75m (2ft 5in) on the 310 DS, 0.9m (2ft 11in) on the 35 DS or 0.95m (3ft 1in) on the 40 DS – a twin keel might well be a better option.

How are the keels attached?

The design of the keel is important but the way they are attached is just as important, if not more so. All of our fixed keels are through-bolted. Every keel has a wide flange at the root (top) of the keel and the flange sits into a reinforced recess in the hull. The flange and the recess work together to spread the loads of the keel/s into the yacht’s hull. The keels are bonded and bolted to the hull. We use up to twelve 20mm and 24mm bolts (per keel) and these go through rolled stainless steel backing plates inside the hull to spread the bolt loads evenly into the fully laminated keel grid which goes all the way up to the chainplates and also carries the mast support.

For our lifting swing keel, we laminate a substantial keel box as part of the hull to accept the keel and the hydraulic mechanism needed to retract the keel into the hull. Unlike most other boatbuilders we don’t use a grounding plate to take the weight of the yacht, our yachts sit on the length of the leading edge of the keel. Integral keels with the majority of the ballast in the grounding plates move the ballast (weight) from low down in the keel to inside the hull. This negatively affects the stability as the more weight you have lower down, the better.

We also don’t like grounding plates because they bring the hull in contact with the ground. By leaving 10-15 cm (4-6in) of the keel out of the hull when it’s retracted, most of the time the hull is kept clear of the beach and anything that could damage it.

The problem with too much form stability

With only 15-12% of their ballast in the centreboard, most lifting-keel yachts cannot rely on keel weight for stability so their hulls need to be designed with extra form stability instead. This means the hull sections have to be much wider and flatter. A flat-bottomed hull is not what you want for a comfortable ocean cruising yacht; it isn’t sea-kindly or easy to steer in waves and gusty winds conditions. We don’t make that compromise at Sirius. With all the ballast in the swinging part of our swing keel design, we can use the same seaworthy, ocean-capable hull shape designed for our yachts with fixed keels.

If you don’t know which keel would be best for your Sirius, contact us to discuss the type of sailing you intend to do, where you want to sail and what your cruising aspirations are.

General Manager – Torsten Schmidt SIRIUS-WERFT GmbH Ascheberger Straße 68 24306 Plön/Holstein

Fax: 0049 – 4522 – 744 61-29

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Keel design for shallow water

As luxury yachts grow in length and volume, so their draught also needs to increase. But the deeper the draught, the fewer harbours and marinas become available. Balancing the need for shallow draught with the design requirements for performance is tricky.

The lifting keel seems to offer a decent compromise, and is becoming increasingly popular. However the technical challenges are considerable, and then there's the added cost. One of the most impressive and extreme examples of lifting keel technology can be found on the recently launched _Hetairos _(known during her build as Panamax), the 60m ketch designed by Dykstra Naval Architects and Reichel/Pugh Yacht Design, and built by Baltic Yachts in Finland.

With the keel fully down, Hetairos draws nine metres, although there is also an intermediate keel position of six metres draught for navigating shallower waters. In the fully raised position, the keel will draw 3.5 metres.

Furthermore it is possible to raise the keel from nine metres to the six metre position while the boat is sailing and the keel is under load. This operation adds such immense loads and demands that the keel trunk is constructed incredibly strongly.

Naval architect at Dykstra, Erik Wassen is rightly proud of his involvement in designing Hetairos, but doesn't believe that the ability to raise the keel while sailing is necessarily something that other owners should aspire to.

'It adds a lot of complications, incredible complexity to the bearings and the structure,' he says. 'The cylinders need to be much stronger than if you don't have that requirement. But it will be interesting to see if we have similar requests in the future.'

According to Wassen, the owner of Hetairos was particularly keen to have the ability to raise the keel while sailing, because he plans to go racing with smaller boats, around racing buoys in just seven or eight metres of water, less than the yacht's maximum draught. As Wassen says, the complications go beyond the purely technical: 'When we start raising the keel during racing, we also wonder how the yacht's handicap will be affected.' It will be an interesting test case for the rule makers.

As yachts grow to the proportions of Hetairos, some interesting problems arise as Jim Pugh of Reichel/Pugh points out: 'As boats get bigger, with the increase in displacement, the loads become so much higher. The larger boat means heavier scantlings and higher loads making for a higher overall structural weight and lower ballast ratio. Compared with a smaller boat you're actually losing (ballast ratio) stability. This means you have to look at other ways of gaining stability a canting keel, water ballast or a lifting keel.'

For_ Hetairos_, the lifting keel is also supplemented by up to 24 tonnes per side of water ballast.

In the case of Vertigo , the 67.2m Philippe Briand ketch built by Alloy Yachts, the design team investigated the possibility of a lifting keel but in the end decided on a simpler solution a 5.1 metre draught fixed keel with a carbon composite daggerboard that can be lowered through the bottom of the keel to increase draught to 9.1 metres.

'When we started looking at the possibility of a lifting keel,' recalls Briand, 'we found ourselves venturing into an unexplored area. Today I believe Kokomo , at 59m, has the largest lifting keel ever. But it is very uncommon at this size. After discussions with the owner and everyone involved, we decided not to go for so much complexity.'

Akalam , a 32m yacht designed by Íñigo Toledo of Barracuda Yacht Design, is similar to Vertigo : she has a fixed 3.6 metre draught keel with a daggerboard that takes the draught to 5.5 metres.

The possibility of canting keels

But what of the canting keel? It's had a chequered history in the world of grand prix racing such as the Volvo Ocean Race and the Vendée Globe where we have seen numerous breakdowns of canting keel technology. The number of life-threatening incidents should be enough to put any safety conscious cruising sailor off the idea.

Jim Pugh, however, says it would be unfair to dismiss the concept entirely. With Reichel/Pugh having designed the likes of Alfa Romeo and Wild Oats

'They're certainly worth looking at for the massive gain in stability you can achieve,' says Pugh, although he admits they are expensive and high maintenance, and require a constant and reliable power source (and back-ups) such as a running engine available to power the keel from side to side.

Like Reichel/Pugh, Finot Conq is a design office perhaps best known for its work in the grand prix race world, but which now finds itself in increasing demand from ambitious superyacht owners looking for high-performance cruising yachts. The French design house beat off strong competition for the right to design a new 30m yacht with the simplest yet most ambitious of briefs from the client: to design 'the world's fastest 100-foot cruising yacht'.

The resulting FC Cube 100' would seem an obvious candidate for a canting keel, but as Finot Conq's David de Premorel explains, they decided against it. 'We did look at having a keel that was both lifting and canting, but it would have been a big weight penalty.

'Since the intention for the boat is to do some of the big offshore races, you need a minimum AVS an angle of vanishing stability of about 105 degrees for a boat of that size. It's something that is indirectly specified in the sailing instructions of these races, and also a basic safety feature for the boat. The problem with a canting keel is that, once you're canted, your capsizing angle decreases.

'If you want a canting keel and the same minimum capsizing angle, you need either a deeper draught or more bulb weight to compensate.'

In the end the canting keel option was rejected on safety grounds, but also with the problems of maintenance making it less attractive too. Instead, the FC Cube 100' is being built with a lifting keel giving a 5.4m maximum draught.

'We would have loved to have an even deeper maximum draught,' says de Premorel, 'but the lifting movement of the keel is limited by the height of the hull and deck. If you limit yourself to a certain figure when the keel is up, it mechanically limits you to a certain draught when the keel is down.'

The only other option would be to install the lifting ram above deck, and apart from the technical challenges, for most superyacht owners this would be too much of an aesthetic sacrifice.

So what other options are out there? If you can't achieve sufficient righting moment with one keel, what about having two? After all, we're used to the idea of two masts. Briand doesn't dismiss it as such a silly idea.

'Twin keels have been done in the America's Cup for some time, and it's a configuration we studied when we've been involved in design projects for the Cup. So we know a bit about this, and yes, this could be a solution for bigger boats.

'Maybe one time we will do it; the only problem we have with that is the ability for tacking and manoeuvring, as having one keel forward and one aft has a big effect.'

However, as Briand acknowledges, if the 'tandem' keel was worth considering for America's Cup racing, and all the tight manoeuvring that this kind of racing entails, it should be good enough for the more sedate world of blue-water cruising.

'I wouldn't be surprised to see this in the future,' he says. 'We certainly wouldn't rule out the possibility.'

While the tandem keel remains just a concept at superyacht level, one alternative configuration that is already making its way in the superyacht world is what Briand refers to as a 'centreboarder', otherwise known as a 'whale body'.

Instead of a standard keel configuration with a lead bulb attached to the end of a long fin, a centreboarder sees lead ballast incorporated into the bilge to provide the necessary stability. A lifting centreboard then pivots up and down to provide the lateral resistance whilst sailing, fitting into a recess in the hull for minimum draught when not required.

Briand is well acquainted with this concept. 'We have done probably more than a thousand production boats like this so we know the naval architecture of this configuration. But this is not the kind of solution I have considered for large yachts, because compared with a lifting keel, it has a lot of downsides. It leads to a heavier boat. And the efficiency of the centreboard is also in doubt, because it requires an opening in the bottom of the hull and creates some drag. It is a much less interesting solution as far as the performance of the boat is concerned.'

Nevertheless, there is a growing demand from owners who are prepared to compromise ultimate performance for the ability to reduce draught to its absolute minimum. Malcolm McKeon of Dubois Naval Architects relates the story of Nirvana , a 53.5m, 2007 Vitters-built ketch.

'The owner wanted to go world cruising with his family, and in order to be able to anchor near the beach, he didn't want more than three metres of draught,' he says. 'We thought, as the design developed, we could convince him that it was unusual to go that shallow, and that we would persuade him to increase the draught to 4.5 or five metres, which is a more conventional fixed draught for a boat that size.'

When it became obvious that the owner really wasn't going to accept a draught of more than three metres, the design office started looking at a variety of lifting keel and centreboard ideas.

'There are two ways of achieving stability with increased draught or increased beam. So with the extreme shallow draught, we opted for more beam and at the same time all the ballast was placed internally; in this instance we had to use 50 per cent more ballast than we would have done on a boat of this length.'

Nirvana's generous 11.6m beam is about a metre wider than it might otherwise have been; with the pivoting centreboard down, the draught increases from three metres to a whopping 10m.

'The efficiency of the yacht under sail is exceptional,' says McKeon. 'The centreboard is a very high aspect ratio foil so it was made out of high tensile stainless steel to withstand the extreme loads. We tank-tested the design to confirm sailing performance.'

One of the additional benefits of the centreboard is how well it dampens the seasickness-inducing roll of a large yacht downwind, and while the pure performance will never live up to a lifting keel alternative, the success of Nirvana has now led to a variation on the centreboard theme with the 57.5m ketch built by Royal Huisman,_ Twizzle_, and to a third-generation 56m centreboarder currently under construction at Alloy Yachts.

Iñigo Toledo is also a fan of the centreboard concept and sees considerable hydrodynamic benefits compared with a conventional keel.

'A fixed keel in a big yacht is limited by draught the keel has to be short in height and long to accommodate the amount of area required [for lateral resistance]. With the daggerboard you get something higher aspect, deeper and narrower which is more efficient, more like a glider wing,' he explains.

'Also you have to build [a conventional keel] with a certain thickness and geometry so that it holds the weight of the ballast. There are structural constraints, whereas when you make a daggerboard you can actually just make the most hydrodynamically efficient profile.'

Toledo also believes the specialist nature of daggerboard manufacture results in a higher quality fin.

'When people make daggerboards they somehow make much more effort to achieve a really good finish, more than when the keel is part of the hull. When you order a daggerboard from a composite materials company, the result is much better.'

McKeon sees more centreboarder superyachts, and Toledo agrees: 'I would say in the future you will probably find 50 per cent of boats with fixed keels and 50 per cent with some kind of movable appendage,' says Toledo. 'Probably about 10 per cent will be lifting, and maybe the other 40 per cent will have daggerboards.'

The compromise between draught and performance is the perennial challenge of yacht design

Quite a prediction, given that every designer we spoke to acknowledges that a centreboarder will always struggle to match the performance of a lifting keel equivalent. What happens when you decide to take your shallow-draught cruiser to a regatta?

'The problem with regattas is that the comparison is too fair and too cruel,' admits Toledo. 'You find out exactly where you are performance-wise. Some owners just don't accept it.'

Better then to stay away? McKeon offers an alternative view.

'What I think is great is when owners participate in these regattas, they can experience the full performance potential of their yacht. Some owners when they're cruising are nervous about pushing the boat and how much one can safely heel over, whereas during a regatta the yachts are pressed a lot harder and they achieve more speed and ultimately the owners have more fun sailing their yacht.'

The compromise between draught and performance is the perennial challenge of yacht design. Whatever kind of configuration you prefer, Briand encourages all owners to take an interest in the appendage package of their yacht.

'When you design a racing boat, it's the first area you study,' he says. 'However, because appendages are underwater and never seen, they're easily forgotten, but the appendage package is a big part of how the yacht performs. It is hugely important to determining the final quality of the yacht.'

Originally published: September 2011.

Kos Picture Source, Rick Tomlinson

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Monaco Yacht Show 2024: The Biggest, Boldest and Most Expensive Superyachts To See

Even in its 33rd year, Monaco Yacht Show continues to break its own milestones.

By Ellys Woodhouse and Toby Louch

The principality of Monaco has a calendar that’s filled with major events. While the financial benefits of this little tax haven ensure its population remains fairly well stocked with super-rich and socialites year-round, it’s these events that truly bring the masses. April calls for the tennis at The Rolex Monte-Carlo Masters; in May it’s time for the Formula One Grand Prix ; June brings the world-famous car show Top Marques ; and summer draws to a close with perhaps the most glam of the bunch, the Monaco Yacht Show, which this year falls on September 25 – 28.

For those interested in gazing upon some of the finest yachts that can be found anywhere in the world, Monaco ’s Port Hercules is a pretty good spot year-round, but for the weekend of the Monaco Yacht Show, things enter a different league.

The Monaco Yacht Show is essentially a gathering of the global superyacht community. From owners to innovators, manufacturers and brokers, all head to the principality. Each year, builders and brokers present around 120 superyachts and 60 luxury tenders , with many of these reflecting current industry trends and revealing the potential future direction of the industry. These vessels boast an average length of around 160 ft, with a sprinkling of superyachts that top the 320 ft mark – with this year’s headliner clocking in at 400 ft.

Aside from the yachts themselves, visitors can expect countless designers improving yacht interiors and engineers working to ensure the industry becomes more sustainable. There’s sure to be a lot going on.

So ahead of this year’s event, Elite Traveler has looked into which yachts will be on display at Port Hercules and curated a list of some of the show’s unmissable vessels. So blow the dust off your Panama hat and add a few zeros to your credit card limit, because these are some of the biggest, boldest and most expensive boats attending the 2024 Monaco Yacht Show.

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H3: The Market’s Most Expensive Superyacht Debuts a New Design

The undisputed biggest headline of this year’s show – in every sense of the word – Lürssen’s Kismet will be the largest yacht to go on display in Port Hercules. While the previous title holder was another from Lürssen, the 377.6-ft Ahpo, the Kismet takes its victory by a considerable mile, clocking in at 400 ft. Previously known as Project Jag, the Kisamet was handed over to owner Shahid Khan in May 2024, making it one of the show’s newest deliveries, too. 

With exterior design by Nuvolari Lenard and naval architecture by Lürssen Yachts along with Reymond Langton Design working on the yacht’s interiors , Kismet is decked out with a helipad, beauty salon, indoor and outdoor cinema, dance floor and gym. Perhaps unsurprising, but all this makes Kisamet one of the most expensive yachts to charter , too, asking for €3m (approx. $3.4m) per week with Cecil Wright & Partners. 

[See also: How Louis Vuitton Made the America’s Cup the Voyage en Vogue]

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Delivered in 2019 by SilverYachts and refitted in 2024, the almost 280-ft, self-described ‘sports activity vessel’ Bold takes center stage at Monaco Yacht Show 2024. Designers Espen Øino created the superyacht’s striking, military-inspired exterior, creating a unique glass-enclosed loft on the upper deck that covers over 3,200 sq-ft of interior space. Meanwhile, Vain Interiors has created an opulent, New York-style loft, which is built to accommodate up to 12 overnight guests in eight luxurious staterooms and can carry up to 96 passengers while cruising.

With a a huge selection of water toys, a vast outdoor entertaining area with a bar and Teppanyaki grill, a cinema, an eight-person hot tub and a lounge surrounding a firepit, it’s no surprise that the Bold is a popular charter yacht, with Holl Robinson asking €875,000 ($972, 800) per week. 

Following an extensive, three-year rebuild, the most expensive superyacht on the market has returned to Port Hercules for 2024, complete with a new look – and price tag, too, asking for €295m ($328m). The 344.5-ft Oceanco H3 superyacht has already picked up a handful of international awards for the new look and is expected to impress many fans at Monaco Yacht Show 2024. 

In addition to the extra 10 meters that were added to the H3 ’s hull, the rebuild – from the likes of Reymond Langton Design, which worked on both the exterior and interior redesign, and the collaboration between Lateral Naval Architects and Oceanco on its naval architecture – also saw a pool deck, huge spa and wellness area and climate-controlled winter garden added to H3 ’s numerous amenities. 

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With its distinctive, shark-like exterior design, the 295-ft superyacht DAR will be hard not to miss at Monaco Yacht Show 2024. Built by Oceanco with exteriors designed by Luiz de Basto Design, the glossy black silhouette was inspired by the look of the hammerhead shark, with sinuous lines, wide set wing stations and a mast modeled after a dorsal fin. 

Meanwhile, renowned Italy-based studio Nuvolari & Lenard has crafted swooping, contemporary interiors. DAR’s impressive features include a complete owner’s deck, complete with a private salon and jacuzzi, a wellness area, an impressive beach club, and two helipads for private use. Offering grandeur and complete privacy in equal doses, DAR can accommodate up to 14 guests in overnight accommodation, with separate living quarters to host as many as 31 crew members.

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Despite only hitting the waters in June this year, the first wallywind110, Galma , is set to make its global debut at Monaco Yacht Show 2024. Measuring almost 110 ft, Galma ’s naval architecture comes from German studio judel/vrolijk & co while interior and exterior lines are designed by Wally in collaboration with Santa Maria Magnolfi. With a design that offers the comfort of a cruising yacht while maintaining the performance of a racing boat, Galma is characterized by the 22.6-ft telescopic keel and an all-carbon hull that has been painted in light metallic blue.

Other highlights of Galma include an 860-sq-ft full-beam cockpit with seating and dining for up to 15 people, as well as an open-plan raised saloon. Galma can accommodate up to eight guests overnight, with five crew members. 

monacoyachtshow.com

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Ellys Woodhouse

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Sailing yachts like Mike Lynch's are 'unsinkable bodies', CEO of boat manufacturing firm says

Bayesian superyacht which sank off Italy is an "unsinkable" vessel, Giovanni Costantino, CEO of The Italian Sea Group, said.

By Ashna Hurynag, news correspondent and Eleonora Chiarella, producer

Sunday 25 August 2024 08:48, UK

Vessels like Mike Lynch's stricken superyacht are "unsinkable", according to the chief executive of the firm which makes and sells them.

Giovanni Costantino, CEO of The Italian Sea Group, told Sky News there are no flaws with the design and construction of the Bayesian superyacht which capsized in a storm off the coast of Porticello, Sicily, on Monday.

Five bodies were found by divers on Wednesday - taking the number of confirmed dead to six.

The Italian Sea Group also owns the firm that built British tech tycoon Mr Lynch's Bayesian, and Mr Costantino said the vessels "are the safest in the most absolute sense".

"Being the manufacturer of Perini [boats], I know very well how the boats have always been designed and built," he said.

"And as Perini is a sailing ship... sailing ships are renowned to be the safest ever."

He said their structure and keel made them "unsinkable bodies".

Read more on this story: Why search of superyacht wreck has been so difficult Hero mum 'slept with baby on deck when storm sank yacht'

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Mr Costantino said news of the sinking "put me in a state of sadness on one side and of disbelief on the other".

"This incident sounds like an unbelievable story, both technically and as a fact," he said.

It is understood Italian prosecutors investigating the incident are continuing to hold interviews with the survivors.

On Tuesday they questioned the captain for more than two hours to help reconstruct what happened and provide useful technical details.

Four British inspectors are also in Porticello and have begun a preliminary assessment of events.

It is understood they will look at all relevant aspects of the incident, including the design, stability, and operation of the vessel. They will also examine the effects of the weather conditions experienced.

Keep up with all the latest news from the UK and around the world by following Sky News

Twenty-two people were on board the vessel, 15 of whom were rescued - including Briton Charlotte Golunski and her one-year-old daughter Sofia.

Divers will resume efforts on Thursday morning to bring ashore a body they found earlier. One more person remains missing.

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37 Facts About Novosibirsk

Written by Adelice Lindemann

Modified & Updated: 05 Sep 2024

Reviewed by Sherman Smith

Novosibirsk, often referred to as the “Capital of Siberia,” is a vibrant and dynamic city located in southwestern Russia. With a population exceeding 1.5 million residents, it is the third most populous city in Russia and serves as the administrative center of the Novosibirsk Oblast.

Nestled along the banks of the Ob River, Novosibirsk is renowned for its rich cultural heritage, scientific advancements, and picturesque landscapes. As the largest city in Siberia, it offers a perfect blend of modern and traditional attractions, making it a fascinating destination for both locals and tourists.

In this article, we will delve into 37 interesting facts about Novosibirsk, shedding light on its history, architecture, natural wonders, and cultural significance. Whether you are planning a visit or simply curious about this intriguing city, these facts will give you a deeper understanding of what Novosibirsk has to offer.

Key Takeaways:

• Novosibirsk, the “Capital of Siberia,” is a vibrant city with a rich cultural scene, stunning natural landscapes, and a strong sense of community, offering a high quality of life for its residents.
• From being a major industrial and transportation hub to hosting world-class cultural institutions and scientific research centers, Novosibirsk is a dynamic city with a diverse culinary scene and a thriving IT and tech industry.

Novosibirsk is the third-largest city in Russia.

Situated in southwestern Siberia, Novosibirsk has a population of over 1.6 million people, making it one of the largest and most vibrant cities in the country.

The city was founded in 1893.

Novosibirsk was established as a railway junction on the Trans-Siberian Railway, playing a significant role in the development of Siberia.

It is known as the “Capital of Siberia”.

Due to its economic and cultural significance, Novosibirsk is often referred to as the capital of Siberia.

Novosibirsk is a major industrial center.

The city is home to a wide range of industries, including machinery manufacturing, chemical production, energy, and metallurgy .

It is famous for its scientific and research institutions.

Novosibirsk hosts several renowned scientific and research institutions, contributing to advancements in various fields including nuclear physics, chemistry, and biotechnology.

The Novosibirsk Opera and Ballet Theatre is one of the largest in Russia.

This iconic cultural institution showcases world-class ballet and opera performances and is a must-visit for art enthusiasts visiting the city .

The city has a vibrant theater scene.

Novosibirsk boasts numerous theaters, showcasing a wide variety of performances from traditional plays to experimental productions.

Novosibirsk is a major transportation hub.

Thanks to its strategic location on the Trans-Siberian Railway, the city serves as a crucial transportation hub connecting Siberia with other regions of Russia .

The Ob River flows through Novosibirsk.

The majestic Ob River adds to the city’s natural beauty and provides opportunities for recreational activities such as boating and fishing.

Novosibirsk is known for its harsh winter climate.

With temperatures dropping well below freezing in winter, the city experiences a true Siberian winter with snowy landscapes.

The Novosibirsk Zoo is one of the largest and oldest in Russia.

Home to a wide variety of animal species, including rare and endangered ones, the Novosibirsk Zoo attracts visitors from near and far.

Novosibirsk is a center for academic excellence.

The city is home to Novosibirsk State University, one of the top universities in Russia, renowned for its research and education programs.

The Novosibirsk Metro is the newest metro system in Russia.

Opened in 1985, the Novosibirsk Metro provides efficient transportation for residents and visitors alike.

Novosibirsk is surrounded by picturesque nature.

Surrounded by stunning landscapes, including the Altai Mountains and the Novosibirsk Reservoir, the city offers numerous opportunities for outdoor activities.

The Novosibirsk State Circus is famous for its performances.

Showcasing talented acrobats , clowns, and animal acts, the Novosibirsk State Circus offers entertaining shows for all ages.

Novosibirsk is home to a thriving art scene.

The city is dotted with art galleries, showcasing the works of local and international artists .

Novosibirsk has a diverse culinary scene.

From traditional Russian cuisine to international flavors, the city offers a wide range of dining options to satisfy all taste buds.

The Novosibirsk State Museum of Local History is a treasure trove of historical artifacts.

Exploring the museum gives visitors an insight into the rich history and culture of the region.

Novosibirsk is known for its vibrant nightlife.

The city is home to numerous bars, clubs, and entertainment venues, ensuring a lively atmosphere after dark.

Novosibirsk has a strong ice hockey tradition.

Ice hockey is a popular sport in the city, with local teams competing in national and international tournaments.

The Novosibirsk State Philharmonic Hall hosts world-class musical performances.

Music lovers can enjoy classical concerts and symphony orchestra performances in this renowned venue.

Novosibirsk is home to the Akademgorodok, a scientific research town.

Akademgorodok is a unique scientific community located near Novosibirsk, housing numerous research institutes and academic organizations.

Novosibirsk has a unique blend of architectural styles.

The city features a mix of Soviet-era buildings, modern skyscrapers, and historic structures, creating an eclectic cityscape.

Novosibirsk is an important center for ballet training and education.

The city’s ballet schools and academies attract aspiring dancers from across Russia and abroad.

Novosibirsk is a gateway to the stunning Altai Mountains.

Located nearby, the Altai Mountains offer breathtaking landscapes, hiking trails, and opportunities for outdoor adventures.

Novosibirsk hosts various cultural festivals throughout the year.

From music and theater festivals to art exhibitions, the city’s cultural calendar is always packed with exciting events.

Novosibirsk is a green city with numerous parks and gardens.

Residents and visitors can enjoy the beauty of nature in the city’s well-maintained parks and botanical gardens.

Novosibirsk is a center for technology and innovation.

The city is home to several technology parks and innovation centers, fostering the development of cutting-edge technologies.

Novosibirsk has a strong sense of community.

The residents of Novosibirsk are known for their hospitality and friendly nature, making visitors feel welcome.

Novosibirsk is a paradise for shopping enthusiasts.

The city is dotted with shopping malls, boutiques, and markets, offering a wide range of shopping options.

Novosibirsk has a rich literary heritage.

The city has been home to many famous Russian writers and poets, and their works are celebrated in literary circles.

Novosibirsk is a popular destination for medical tourism.

The city is known for its advanced medical facilities and expertise, attracting patients from around the world.

Novosibirsk has a well-developed public transportation system.

With buses, trams, trolleybuses, and the metro, getting around the city is convenient and efficient.

Novosibirsk is a city of sport.

The city has a strong sports culture, with numerous sports facilities and opportunities for athletic activities .

Novosibirsk has a thriving IT and tech industry.

The city is home to numerous IT companies and startups, contributing to the development of the digital economy.

Novosibirsk celebrates its anniversary every year on July 12th.

The city comes alive with festivities, including concerts, fireworks, and cultural events, to commemorate its foundation.

Novosibirsk offers a high quality of life.

With its excellent educational and healthcare systems, cultural amenities, and vibrant community, Novosibirsk provides a great living environment for its residents.

Novosibirsk is a fascinating city filled with rich history, stunning architecture, and a vibrant cultural scene. From its origins as a small village to becoming the third-largest city in Russia, Novosibirsk has emerged as a major economic and cultural hub in Siberia . With its world-class universities, theaters, museums, and natural attractions, Novosibirsk offers a myriad of experiences for visitors.

Whether you’re exploring the impressive Novosibirsk Opera and Ballet Theater, strolling along the picturesque banks of the Ob River, or immersing yourself in the city’s scientific and technological achievements at the Akademgorodok, Novosibirsk has something for everyone.

From its iconic landmarks such as the Alexander Nevsky Cathedral to its vibrant festivals like the International Jazz Festival , Novosibirsk has a unique charm that will captivate any traveler. So, make sure to include Novosibirsk in your travel itinerary and discover the hidden gems of this remarkable city.

Q: What is the population of Novosibirsk?

A: As of 2021, the estimated population of Novosibirsk is around 1.6 million people.

Q: Is Novosibirsk a safe city to visit?

A: Novosibirsk is generally considered a safe city for tourists. However, it is always recommended to take standard precautions such as avoiding unfamiliar areas at night and keeping your belongings secure.

Q: What is the best time to visit Novosibirsk?

A: The best time to visit Novosibirsk is during the summer months of June to September when the weather is pleasant and suitable for outdoor activities. However, if you enjoy the winter chill and snow, visiting during the winter season can also be a unique experience.

Q: Are there any interesting cultural events in Novosibirsk?

A: Yes, Novosibirsk is known for its vibrant cultural scene. The city hosts various festivals throughout the year, including the International Jazz Festival, Novosibirsk International Film Festival, and the Siberian Ice March Festival.

Q: Can I visit Novosibirsk without knowing Russian?

A: While knowing some basic Russian phrases can be helpful, many establishments in Novosibirsk, especially tourist areas, have English signage and staff who can communicate in English. However, learning a few essential Russian phrases can enhance your travel experience.

Novosibirsk's captivating history and vibrant culture make it a must-visit destination for any traveler. From its humble beginnings as a small settlement to its current status as Russia's third-largest city, Novosibirsk has a story worth exploring. If you're a sports enthusiast, don't miss the opportunity to learn more about the city's beloved football club , FC Sibir Novosibirsk. With its rich heritage and passionate fan base, the club has become an integral part of Novosibirsk's identity.

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Our commitment to delivering trustworthy and engaging content is at the heart of what we do. Each fact on our site is contributed by real users like you, bringing a wealth of diverse insights and information. To ensure the highest standards of accuracy and reliability, our dedicated editors meticulously review each submission. This process guarantees that the facts we share are not only fascinating but also credible. Trust in our commitment to quality and authenticity as you explore and learn with us.

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Password --> (color vector graphic design) Type of vectorization:   from 20 vector images ($27.95) Available vector graphic file formats and file size: EPS 8 79.0 kb CorelDraw 9 74.2 kb Windows MetaFile 79.7 kb ** 1600x1522 px 305.4 kb or   ›› Ship & Download: $44.95 ›› At least 8105 vector images by keywords: › › › › › › › › › › 13 Popular Full Keel Sailboats Worth Considering Full keel sailboats are very stable and durable - they are great for cruising long distances. But there are disadvantages too. Let's look at what models to consider, and why. Here are 13 good full keel sailboats that are worth considering: Nicholson 32 Island packet 380, folkboat 25, cape dory 36, vancouver 32, tradewind 33, endurance 50, westsail 32, hans christian 52. First of all let's have a look at why you should even be preferring full keel sailboats to a more traditional, widespread classical fin keel design. Full Keel Advantages As with everything, there are plenty of pros and cons on each side. Full keels generally provide better handling if the weather gets tricky, they track better, provide more stability downwind, and generally stabilize the boat movements better. Furthermore, they are way more robust, thus less prone to damage. Running ashore isn't as big of a deal as it is with a fin keel and your rudder and propeller will be more protected with the mass of the keel in front of them. Full Keel Disadvantages With more mass and drag comes less speed. Plus the large surface area underwater holding the direction will result in a wider turning radius, which might be annoying in smaller spaces. Fin Keel vs Full Keel: Pros and Cons & When to Choose Which Fin keel advantages. The largest advantage of fin keels is their speed. They also provide better maneuvering and a better turning radius. Fin Keel Disadvantages It is inevitably more prone to damage though, wear and tear will be a way bigger issue than a full keel. They won't have your back when a gust comes since the water-resistance to the side will be smaller. It seems then that for serious longer passages, liveaboards, and long-term sailing, full keels are better. As long as you don't care for speed as much, but are concerned about the boat having your back, this is the answer. So let's now look at the superstars of the full keel universe. The very prototype of a long-distance tough cruiser. It has been with us since 1963 and happens to be among the first fiberglass boat models produced on a mass scale. Nicholson 32 went out of production in 1981 and it was a model approved for the 2018 Golden Globe Race, proving that even older Nicholsons are still standing strong due to their toughness and ease of repair. They were supposedly as durable as if made out of steel. Though I'll leave up to you whether you want to see that as a marketing claim or reality, such a statement can not be made without some base. Plus the newer models have a lot of interior space, are manageable for solo sailing, and provide a sturdy ride to take one around the world. The story here is similar to the above Nicholson - meaning that we are looking at one long-lasting high-quality cruiser. Not just because of this specific model's build - Island Packet in general was always known for this. And it is among the very few companies that, in the modern era, keep making full keel boats. In other words, you don't see many shipyards focusing on full keels these days, so if you want one and you would rather go with a new boat, Island Packet will be one of the stops you will very probably make when doing your research. If you are looking for reliable cruisers, you will like this one, since cruising is what it was built for, even if it meant sacrificing some performance aspects. It has a wide beam, a lot of interior space, all of the amenities a comfy cruiser should have, such as a big refrigerator with a freezer, as well as a fully equipped kitchen. The long keel here serves as a comfort helper, since, as mentioned before, it adds to the stability and reduces motion. Not to sound repetitive, but the word 'reliability' has to be mentioned again. It seems that boat builders who choose the full keel design have something in common. But since this particular boat was born during the Second World War and has been going strong to this very day, what other words to describe it? It has the Nordic blood in its veins since it was thought into existence by the Scandinavian Yacht Racing Union and since it prefers just about everything over comfort. The boat is very stable, not just because of its full keel, but also because of its insane 55% ballast ratio. For those who haven't come across this before, the ballast ratio is the ratio of the ballast weight relative to the boat weight. So for instance the nearly 9 tonne Bavaria 40 with its almost 3 tonne ballast has a ballast ratio around 30 percent. Thus you can imagine that a boat that 'wastes' more than half of its weight on ballast is serious about rigidity. These are performance racer numbers. But of course, if you are designing a boat that has to withstand the Scandinavian storms, you don't have a choice than to go overboard with specs. So if this toughness is what you seek, look no further. ...although as far as I know, all Cape Dory boats have full keels, regardless of their length. Their 36-foot model is just their most popular one. Cape Dories are known for their sturdiness, ability to cross the oceans because of their stability, and relative ease of handling. They were engineered by Carl Alberg, who was inspired by the Scandinavian Folkboat, where reliability is worth more than comfort, or the interior space. This boat rocks a heavy rig for hardcore traveling, but its 1.5-meter draft makes it ideal for coastal cruising as well. What's quite interesting about this particular model is that during its lifespan it went through very few changes. Boats usually evolve, sailors' feedback is taken into consideration for upgrades, but Cape Dory 36 remained relatively unchanged inside or out. This is a big compliment, since the brand started out in 1963, stopped production in 1991, and sold its blueprints so that they could be built further. Talk about longevity. Let's progress in technology! Just because a long keel is an old-fashioned or more traditional approach, it doesn't mean it remains monolithic in its ideology. There were innovations in the concept, such as cutaways in the keel, to reduce the biggest drawback of this design, the drag. So it only makes sense that Vancouver, a company that had distinctiveness and innovation in its mission and vision, would take part in this. Their 32-foot model that begun its lifespan in the early eighties, had a deeply cutaway forefoot, plus a rudder that was wider the deeper it was underwater, meaning its widest point was at its lowest point. This was to increase efficiency, and rudder response. Technicalities aside, this boat was very well made, no corners cut, no expenses spared. This resulted in quite pricey vessels, out of reach of many, but much time has passed since, so today it can be yours for around 40 000 USD and up. And since the build quality was so high back then, you can still enjoy a proper boat, usually at a higher quality than boats equal its age. The great thing about Australian sailboat makers is that they design their boats for long passages. How else would they get off of the continent? Freya 39 is a good example of this since it has not only circled the globe many times but also won the Sydney-Hobart Yacht Race three times consecutively. And that's a famously hard race. The boat is built like a tank, with thicker fiberglass walls than you would find in its rivals. Despite that, its owners claim to have crossed over two hundred miles per day on it, a figure that is well known when it comes to this model. Which sounds plausible with its 7.8 kts of hull speed. Its construction makes her one stable boat since it has been noted that during races, it was able to carry a spinnaker longer than its competitors, well into the 30 knots of wind speed. The only drawback here is that if you fancy it, since it is so highly valued, and in demand, it will be tricky to find one to buy. And once you do, prepare to pay around 60 000 - 90 000 USD for it. This one comes with a story attached to it. Once upon a time, a naval engineer Nick attempted to sail around the world. Halfway through, his boat gave up, which meant a lot of trouble for Nick, but he exited this disaster with a pretty precise idea for what his next project would be. He set on to design a boat that would be so sturdy that his sailing misfortune would never repeat. Out of this incident paired with a smart brain, Wylo 2 was born. To make sure his design stands, after putting this boat on the water, he proceeded to live on it, while circling the globe a few times. Others, seeing this success, bought his designs and they became quite widespread. As you might have guessed, this boat has a lot of space for living, for storing equipment and provisions, so it is comfy to live on, not only for your body but because of its sturdiness, for your mind too. These designs have accomplished some astonishing feats in all corners of the world, so if you put your trust in this design, you won't be making a mistake. If I said this boat is sturdy and ready for just about any destination, I'd really be repeating myself now. So while that's true, let's talk about what's special about Tradewinds 33. It has a rather small cockpit, so on-deck dinners while watching the sunset with the whole crew might be a bit improvised, but the space saved is used for an impressively spacious interior as well as a nearly flat deck. So moving about is a pleasure. For liveaboards, this is a good idea, since storage space will be plentiful. Plus it's an elegant looking boat, with a forestaysail as a default setup. So rock on. Time for a larger boat. So that if you want something that won't lack anything you might wish for, including space, I have something for you too. All Endurances are full keels, so if you fancy a smaller model, there is a way. Even though it is relatively new, (you will find models from around 1995) it will make you feel like a medieval pirate, with its old-school helm, wooden interior, and a spacious aft cabin that has large windows facing back! It is a proper bluewater cruiser, built in South Africa based on a famous Peter Ibold's Endurance blueprint. It sleeps a whole family, so if a circumnavigation with a few friends is what you seek, this is one for you. If you are up for some single-handed sailing, pause here for a bit. Small sailboats are usually nimble, on the top of it, this one is also quite sturdy and stable, as full keels are. You won't find much space below the deck, so don't expect to have a party of more than around two people, but at least it's a good looking interior, with charming round windows and many of the usual amenities. They say that Mason sailboats are premium quality for a non-premium price. I wonder whether them being built in Taiwan has something to do with it. Here is a quote by an owner of a 1986 model that says it all: "I am absolutely captivated by the boat and am not objective at all in my feelings toward her. The general construction is of the highest standard. Like an Irish hunter, she is a workhorse and a lady-maybe not quite as fast around six furlongs as a racehorse, but for the long pull, through timber, brush, and over walls, she is really something." Now although this owner admits subjectivity, this boat indeed was built with quality in mind. Sturdiness too - not only is its fiberglass hull properly solid, but it also features longitudinal stringers to add further rigidity. There is a lot of brightwork, which might sound nice at first glance, but since it requires quite a lot of maintenance, some owners even said they could do with less wood if it meant less upkeep. All in all though, when it comes to getting a lot of boat for not a lot of money, this is it. Does it make sense to even praise how heavy and sturdy this boat is built? Probably not at this point. Just know it ticks all the boxes. It is made of 12 layered fiberglass for Pete's sake. The design was based on ideas of the Norwegian engineer Colin Archer, who made his boats such that they could withstand the northern seas. Pair that with the fact that the interior here is surprisingly spacious with 6 ft 2 in of headroom and you've got yourself one comfortable circumnavigator. The issue stemming from the heavy build and a full keel, which is a slower pace, applies here more than usual though. This boat is absolutely reliable, but don't expect winning speed races. Sadly, Westsail 32 was in production only for some 9 years. Sales were booming, they made over 800 boats, but bad business practices and cash flow issues resulted in its demise. Not the author, the boat. If beauty and elegance are what you are after, this one will catch your eye. Just as was the case with Mason, these boats were produced in Taiwan. But since the goal of the engineers was to create the 'ultimate cruising sailboat' and they spared no expense, expect to pay hundreds of thousands of dollars for these boats, even though decades old. The gorgeous classical design paired with the high build quality makes these exclusive pieces of work, plus quite a modern one since they ceased production in the 90s. So if you don't mind the higher price mark and are looking for something relatively new, that will, thanks to the build quality, last you for many years to come, this might be your choice. Full keel sailboats are sturdy. Not only is that because of the full keel which itself provides a lot of structural integrity. But also because the choice of putting the full keel in means you are building something that prefers ruggedness and reliability over anything else. So it is logical that the rest of the boat will be built in the same fashion. So if you don't mind sacrificing the few knots of extra speed, if you don't mind the smaller pool to choose from, if you want a boat that will have your back in pretty much any situation and place you will choose to go to, if you want to sail the Scandinavian design, go for it. Arthur Rushlow What a great page. Both my wife and I sailed Faulk Boats out of Canada prior to our moving to Florida. Once we arrived in Florida we had a Soveral 26 built we raced for three years prior to my returning to College and now 5 degrees later I am an Anglican Bishop with no boat. Leave a comment You may also like, 5 surprising advantages of a full keel sailboat. Modern keel designs favor fin keels, with the high-performance boats using bulbs with narrow chord sections and deep drafts. Very few full keel designs are being … Fin Keel vs Full Keel: Pros and Cons & When to Choose Which 7 Legendary Solo Bluewater Sailboats Worth Considering 13 World-Famous Bluewater Sailboats Under 40 Feet 17 Legendary Bluewater Sailboats Under 50 Feet (with Photos) 203 IMAGES Keel construction and design explained Kiribati 36 aluminum swing keel yacht 12m Blue Water Lifting Keel Explorer Yacht : Owen Clarke Design Keel construction and design explained Keel Keel construction and design explained VIDEO Parker yacht keel box leak 6.5m SAIL YACHT with INTELLIGENT KEEL DESIGN ANDREI ROCHIAN IOM yacht keel bulb machining 4 Radical Loop Keel Design 1988 Cape Dory MKII 30 **SOLD** in Annapolis Maryland- A Muse SL Yacht for Billionaires COMMENTS Keel construction and design explained The Rustler 57 has the option of being fitted with a lifting keel. Its 2.0 (6ft 8in draft makes her a more versatile cruising yacht. In the centre of the keel is a bronze fin that has a chord as wide as the depth of the lead stub. When the blade is retracted, the yacht only draws 2.0m / 6ft 8in and she still sails well. PDF Eric W. Sponberg drag. Below—Nicorette Ill, a bulbed-keel, "triple-moving-foil" racer developed by Simonis-Voogd Yacht Design using the author's software, took line honors in the 2005 Sydney-Hobart race. The forward rudder is a requirement in this arrangement, to provide side force when sailing upwind and the keel is canted. 2.3. Figure 3 illustrates that for any Sailboat Keel Types: Illustrated Guide (Bilge, Fin, Full) A bilge keel is a twin keel which uses double fins, allowing the boat to be beached and rest on its keel upright. Bilge keels have double the wetted surface, which increases comfort and directional stability while decreasing heel. Modern bilge keels often provide decent windward performance, thanks to better design. Sailboat Keel Types Compared: Pros and Cons of 13 Types The dual keel design keeps your boat stable in shallow waters, making it ideal for exploring remote destinations, such as tidal estuaries or hidden coves. Low maintenance: Compared to other keel types like fin keels or lifting keels, bilge keels require less maintenance. They are sturdy and simpler to maintain due to their fixed position. Keel types and how they affect performance Racing influence on keel types and design. Most early yacht designs were schooners, but during the latter half of the 19th century the gaff cutter rig started to dominate the scene. Many notable yachts were built at that time and the most important racing design was probably the yawl Jullanar (1875). Keels in Boats and Ships The bulb increases the keel's weight, enhancing stability and reducing drag. Bulb keels are often found in performance-oriented sailing vessels. 4.4 Wing Keel. A wing keel features a modified fin keel with flattened sides, resembling wings. This design provides additional lift, enabling boats to navigate shallower waters. Mastering the Depths: The Sailboat Keel Guide The keel's influence on a sailboat's performance cannot be overstated. It's a balancing act, quite literally, where the keel's design directly impacts the boat's stability, speed, and maneuverability. The choice between a deep keel and a shallow keel, for instance, is a decision that touches upon the very nature of one's sailing. Keel in Sailing Dynamics The keel is a testament to the sophistication and evolution of boat design, playing a pivotal role in the safety, stability, and performance of sailboats. By understanding the different types of keels and their functions, sailors can better appreciate the intricate dance between vessel, wind, and water, leading to more informed choices and ... A Look at Sailboat Design: Fin Keels vs. Full Keels Keel bolts and the infamous garboard seam are completely eliminated. This approach to sailboat keel design dates back to the Rhodes Bounty II and other prototypes in the production world of sailboats. Now over 50 years old, many of these boats continue to have a tenacious grasp on the lead or iron that they hold. Fixed, Lifting, Telescopic Yacht Keel Configurations TELESCOPIC KEEL. The telescopic keel combines some of the benefits of the fixed keel and lifting keel. It achieves a similar amount of draft adjustment as the lifting keel with only minor intrusion into the interior. The upper, fixed part of this design is installed partly inside the hull but mostly outside and below the hull surface. Sailboat Keel Types: 10 Most Common Keels Explained If you want to watch one video on keel types and just get it, this one is for you. Keels don't have to be confusing; simply classify them the right way. I've... What Is a Sailboat Keel and How Does it Work? The keel is located in the center of the bottom of the boat's hull, combining both hull sides. Sailboat keels extend out from the hull downwards. Depending on the exact keel design, the extended part can run from stem to stern, or just narrowly in the center of the boat's hull. What does a keel do? Keels help boats maintain course by countering ... Keel design: What's best? Ted Brewer reviews the ins and outs and ups and downs of keel design. The purpose of a keel, fin, or centerboard is to provide resistance to making leeway; in effect, to keep the yacht from sliding sideways through the water due to wind pressure on the sails. Various shapes of underwater plane have been in and out of style over the past 150 years. A Quest for Keel Integrity The bible for many naval architects and sailboat designers is The Principles of Yacht Design (PYD) by Lars Larsson and Rolf Eliasson. And when it comes to the crucial links in keeping the ballast attached, the authors justifiably put much stock in hedging a bet. ... The Cal 40 is a classic example of an early fin-keel design with internal lead ... The pros and cons of different keel designs Our keel designs have more weight in the tip (bottom) - using a bulb on the fin and twin keel design and flaring the lower sections on our lifting swing keel yachts. You don't have this with centreboard and integral keel yachts. It might be surprising, but a lot of owners come to us thinking that a lifting swing keel is the best option for ... Which is the BEST Keel Design? Subscribe: https://www.youtube.com/c/riggingdoctor?sub_confirmation=1What is the best keel design for you? Are you going to be racing or will you be cruising... Keel design for shallow water In the case of Vertigo, the 67.2m Philippe Briand ketch built by Alloy Yachts, the design team investigated the possibility of a lifting keel but in the end decided on a simpler solution a 5.1 metre draught fixed keel with a carbon composite daggerboard that can be lowered through the bottom of the keel to increase draught to 9.1 metres. 'When we started looking at the possibility of a lifting ... Monaco Yacht Show 2024: The Biggest, Boldest and Most Expensive With exterior design by Nuvolari Lenard and naval architecture by Lürssen Yachts along with Reymond Langton Design working on the yacht's interiors, Kismet is decked out with a helipad, beauty salon, ... Galma is characterized by the 22.6-ft telescopic keel and an all-carbon hull that has been painted in light metallic blue. Pros and Cons of the Bilge Keel (5 Surprising Benefits) A definite advantage of a bilge keel design is the lower draft. A lower draft will come in handy of course when sailing in shallow areas, like the British coastal waters, when going on lakes or the occasional river. ... Bilge keel boats were for the slow folk, fishermen, who cared for stability and the ability to beach their boat when the day ... Sailing yachts like Mike Lynch's are 'unsinkable bodies', CEO of boat Sailing yachts like Mike Lynch's are 'unsinkable bodies', CEO of boat manufacturing firm says ... He said their structure and keel made them "unsinkable bodies". ... including the design ... 37 Facts About Novosibirsk Novosibirsk is the third-largest city in Russia. Situated in southwestern Siberia, Novosibirsk has a population of over 1.6 million people, making it one of the largest and most vibrant cities in the country.. The city was founded in 1893. Novosibirsk was established as a railway junction on the Trans-Siberian Railway, playing a significant role in the development of Siberia. Novosibirsk (Novosibirsk oblast), coat of arms (1993) The vector image of Novosibirsk (Novosibirsk oblast), coat of arms (1993). The largest online collection of heraldry vector clipart with instant download access for flag-makers and publishers. Flags, coats of arms, seals, crests, insignia - vector images only! 13 Popular Full Keel Sailboats Worth Considering Here are 13 good full keel sailboats that are worth considering: Nicholson 32. Island Packet 380. Folkboat 25. Cape Dory 36. Vancouver 32. Freya 39. Wylo 2. Tradewind 33. Chulym, Chulymsky District, Novosibirsk Oblast Chulym (Russian: Чулы́м) is a town and the administrative center of Chulymsky District in Novosibirsk Oblast, Russia, located on the Chulym River 131 kilometers (81 mi) from Novosibirsk, the administrative center of the oblast.Population: 11,568 (2010 Russian census); 12,275 (2002 Census); 13,703 (1989 Soviet census). It was previously known as Chulymskoye. Novosibirsk Reservoir Novosibirsk Reservoir or Novosibirskoye Reservoir (Russian: Новосиби́рское водохрани́лище), informally called the Ob Sea (Обско́е мо́ре), is the largest artificial lake in Novosibirsk Oblast and Altai Krai, Russian Federation.It was created by a 33 m high concrete dam on the Ob River built in Novosibirsk. [1] The dam, built in 1956, provides a water ... catamaran gulet motorboat powerboat riverboat trimaran yacht