The new J Class sailing yacht Lionheart

20 January 2015 • Written by Oliver Dewar

Lionheart was the third new J Class to be launched since Harold S Vanderbilt's successful America's Cup Defender, Ranger, took to the water in 1937. In 2003, a replica of Vanderbilt's Super J Ranger left the Danish Yacht boat yard and immediately began racing, followed six years later by the J Class replica of Endeavour II, renamed Hanuman, leaving the Royal Huisman Shipyard and competing successfully against Ranger just four months after launching. With the launch of the Hoek Design_ Lionheart_ from Claasen Jachtbouw the stakes have been raised again.

The meeting between the replicas of Ranger and Endeavour II was significant when the duo met in 1930s, Ranger _was victorious, but the more recent _Endeavour II-replica, Hanuman, triumphed on the water 90 years later.

For Andre Hoek, a detailed research program focused on testing the various, original J Class designs revealed that Lionheart was one of the best set of designs available for an all-round, high-performance J.

A model of the completed Lionheart: the new J Class yacht

When an existing client came to us for a third yacht, his main interest was a new J Class yacht,' says Hoek. 'He asked us what we would do if we were to build a new J and that led to a proposal to first do a dedicated research project to determine what would possibly be the best performing J Class yacht.

'We proposed to analyse the theoretical performance of all existing J Class lines and to develop a dedicated Velocity Prediction Program specifically geared to J Class hulls with long keels,' the marine architect explains, 'as the existing VPP software is all for round-bilged hulls with fin keels and spade rudders, which are totally different hydrodynamically to a long keel hull with a rudder that forms a flap on a long keel.'

The proposal was accepted and a new Velocity Prediction Program for typical J Class hulls was developed together with Peter van Oossanen (of wing keel and FDHF fame).

Tank test data of a 20 foot long model of the J Class _Rainbow _was used to calibrate the mathematical formula of the VPP program. With this new software, initially all possible Super Js (with a maximum waterline length of 26.51m) were analysed for performance both on line honours and handicap.

The five best-performing hulls from this research were then analysed using computational fluid dynamics software (CFD). The CFD analysis confirmed the VPP findings and the search was narrowed to three hull designs:

One of the eight tank-tested designs commissioned by Vanderbilt from W Starling Burgess and Olin Stephens for the Ranger 77-F project;

Svea, designed by Sweden's Tore Holm in 1938 but never built; and A Frank C Paine design that didn't progress beyond the drawing board.'Of the final three, Lionheart showed the best overall performance,' Hoek reveals. 'The Paine-designed Atlantis is a very good light wind and downwind boat and Svea is the best upwind boat.'

Furthermore, the research proves that the_ Lionheart_ design is faster than the lines chosen for the original Ranger a choice that was not due to flaws in the combined wisdom of Vanderbilt, Burgess and Stephens, but purely that tank testing with models of just under a metre in length is now known to supply inconclusive and misleading data.

The original lines of the Ranger 77-F project formed the basis for Lionheart

Once the optimum design podium was full, the client purchased the intellectual property rights for the Burgess/Stephens Ranger 77-F designs from Sparkman and Stephens and optimisation began on the_ Lionheart_ hull, rig and sail plan. The process started with recreating the 1937 lines to ensure that both port and starboard matched a common error in early, hand-drawn, pre-digital designs.

Continuing research soon showed that the designs with the buoyancy further forward were more effective; wind tunnel testing produced the sail plan geometry, and rudder angle calculations with the new VPP dictated the mast position.

The next phase in the design process was hull strength and construction. While the original J Class yachts were built in steel, the J Class Association (JCA) allows the modern, replica yachts to use aluminium a farsighted decision by the JCA, but one that raises issues of longitudinal stiffness in yachts possessing the enormous overhangs synonymous with the classic J Class profile.

To prevent the characteristic hogging, sagging and alarmingly slack standing rigging associated with an elastic, aluminium hull, Hoek and his team used a 3D finite element model (FEM) to explore load levels throughout the yacht, resulting in an exquisite, internal lattice of aluminium supports to keep Lionheart stiff, and hull panels of multiple thicknesses dependant on specific load stress areas.

While the overall hull design remained faithful to the original, 1930s J Class remit, one aspect of the replica hulls had to change. 'We are allowed to raise the freeboard by 10cm and make a bulwark of an extra 10cm above the level of the deck,' confirms Hoek. 'These are the only two changes you are allowed to make to the original lines.'

Computational fluid dynamics was used to shape the Ranger 77-F's hull into the Lionheart

The reason the JCA introduced the rule change is simple: 'It has everything to do with the fact that the boats were never built to be equipped with vast interiors, generators, powered winches, galleys and electronics,' Hoek explains. 'There were hardly any interiors in these boats and they were purely built for racing.'

However, J Class purists who fear that the sanctity of the original class rule has been compromised with modern tampering should realise that the truth is somewhat different.

'Most people think that a J Class has an extremely low freeboard with long overhangs,' continues Hoek. 'Especially when you look at the original, surviving boats Velsheda, Shamrock V _and _Endeavour.'

In reality, the modern equipment on Velsheda and _Endeavour _has sunk both yachts by around 30cm below their 1930s waterline.

'None of the surviving Js fit the original Universal Rule now,' he adds.

The Universal Rule ensured that waterline length was no longer than 87 feet (26.51m). 'In some of them, the waterline length is now about 95 feet as they are so much lower in the water,' states Hoek.

Historically, the 26.51m waterline achieved by the Super J yachts was a fundamental advantage an area researched heavily by Vanderbilt.

'In 1936, they did a test with Rainbow and ballasted her down to precisely 26.51m,' recalls Hoek. Sinking the yacht below her natural 24.99m waterline delivered immediate results.

'She was faster than she was before due to the improved righting moment, but still did well in light airs,' he adds. 'The conclusion that a Rainbow-type boat at 26.51m waterline length would be high performance led to all the subsequent Ranger designs.'

The implications of this issue are twofold in terms of performance and aesthetics, for although modern photographs of the surviving yachts suggest that reduced freeboard is more in keeping with tradition, the replica Js with their stretched overall length in the overhangs to compensate for the increased freeboard, share an identical design DNA.

'So, technically, the freeboard of the new boats is higher,' explains Hoek, 'but they are actually closer to the original.'

Lionheart uses an intricate lattice of frames stiffen her aluminium hull to make the J Class's overhangs possible

Lionheart's immaculate hull has been built at the Bloemsma yard, a key player in the current J Class revival, which has also been responsible for the hulls of Atlantis and Rainbow. Lionheart's fitting out was done at Claasen Jachtbouw with a team of 20 craftsmen and specialist contractors working with extraordinary co-ordination in the yacht's slender hull.

Deeper into the boat at the turn of the bilge in an area that charter guests are unlikely to visit the engine room is a masterpiece of space management. Despite the sheer volume of engineering squeezed into such a confined space, it is possible to stand upright and move around without skinning elbows or slipping discs.

And while Claasen Jachtbouw is famous for its exquisite joinery work and attention to detail, technical installations are to very high quality levels as well. MCM from Newport, USA, acted as the owner's representative a team of specialists that have added considerable experience to the build team. Their vast technical and big boat racing experience has also contributed to the end result on board.

For Victor Weerens, the yacht's project manager at Claasen Jachtbouw, Lionheart has been an exceptional experience.

'It has been a great project for us with many challenges,' he admits. 'But the team here and our sub-contractors have met all the demands of building a modern J.'

After launching she was taken up river to Zaandam for the stepping of the clear-coat carbon mast and boom from Hall Spars with Future Fibres PBO rigging.

Bugsy Gedlek; Claasen Jachtbuow; Freddie Bloemsma Aluminiumbuow; and courtesy of Hoek Design

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