Built around the engine box and on top of the hull’s structures, the total weight of the interior – seat, bunks, table, galley, heads, fairing, paint and everything else – is only 150-200kg. Its impact on performance is minimal


judel/vrolijk, the lead naval architect on the project. Cardin’s own personal experience was a good fit, notably his optimisation work on the HH42 Ino XXX (ex-Oystercatcher 30) which kept that nine-year-old production boat at the top of the IRC fleet for four consecutive years, with its offshore performance improving steadily every season (see Seahorse November 2021 issue). ‘We were very focused on Ino and we


‘We learned in CFD that a hollow in the underbody can work very well offshore’


were looking closely at Class40s,’ Cardin says. ‘We had in mind that there was a definite niche where you could combine those two concepts and make a very competitive IRC boat for all-round offshore racing. We started with Ino as a base line, compared it with a Class40 concept and studied the strengths and weaknesses of both directions.’ ‘The j/v43 is very similar to a Class40


in terms of how it’s built and the materials,’ Cardin explains. ‘We stretched the boat to give the clients more interior space. We used what we learned from Ino in terms of appendage design and sail configuration for IRC optimisation. The major difference is that Class40s are not optimised for IRC; that involves different design features, especially for the sailplan. In Class40 they can do pretty much what they want, they can use types of headsail that just don’t work for IRC. So the sailplan for the j/v43 is an evolution of the Ino learning process: flying headsail, inner staysail and so on.’ The operational use of the j/v43, which set the design parameters for the project,


is more broadly based than a typical Class40. Transatlantic races will be part of the mix, along with classic 600-mile events such as the Fastnet and the Middle Sea Race, and perhaps some Caribbean regattas, but the primary focus will be long-distance short-handed racing in the Baltic with two to four crew on board. Inshore racing doesn’t figure in the design brief.


The first step in the design process was


to decide on a scow-type hull. ‘From there we developed eight new hull shapes with


variations in features like chines, flare and maximum beam,’ Cardin says. ‘We ran some trials to pick up the right sort of hull geometry and then presented the results to the clients. It’s not as extreme as a Class40 because we still have a bit of upwind consideration in this concept and with a longer waterline the motion will be easier in waves.’ Proprietary software played a key role.


‘We have been developing our own CFD RANS code to improve the quality of our results,’ Cardin explains. ‘We can run any geometry we want, at any speed; we have a powerful computing cluster in house so


�


The five-winch cockpit layout is directly derived from the new generation of Class40s. Almost all sailing manoeuvres can be done in the shelter of the coachroof overhang


SEAHORSE 67


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