A TP52 is an absolute machine… but park one up alongside the new Infiniti DSS 52 or a Carkeek CF520 IRC racer and even the finest grand prix inshore racer of its generation is starting to looks a little bit last-century. Remember the kick-back when the first modern plumb bows reappeared after being absent since the days of the pilot cutters? Next the dreadnought bow became as contentious a subject as ‘that’ argument over the lee-bow effect; but like its immediate vertical predecessor, today it too is fast becoming the norm
Some maths The Infiniti 52 development has been an interesting project to follow from a rating perspective. During their development phase we
Above: Figure A – initial exploration of configurations for the Infiniti DSS 52
were already undertaking research into how far IRC can go in rating foil-assisted yachts. ‘Assisted’ is the operative word here as the fundamental policy of the IRC rule at this time is to rate ‘a broad range of cruising and racing ballasted monohull keel boats’. We set our limit for a foil to generate
maximum lift of around 30% of boat weight at a typical design speed for the size of the yacht. This in turn limits the maximum lifting-surface area. In reality the foil may produce more than 30% of boat weight in fast conditions, but this is not considered to be a regular sailing situation. In 2021 IRC also introduced the flying
Above: Figure B – the last Bermuda Race was scored Time-on-Distance under ORR but this implied wind speed jump seen after the 10kt TWS mark does look rather dubious…
You can still argue that the TP52 devel-
opment hotbed is what has pushed the game further here than in other sizes, but really this is an area where the rating systems haven’t totally caught on to boats where simple physics allow for more apparent wind sailing and higher speeds in general. Sail development has had to make huge
jumps too in being able to extract the potential performance from these quick boats, and the early trials for the Infiniti 52 in the New Year will be all about learning where the sweet spots in the performance envelope really lie, and then matching the sails around those areas. We are well aware that having the two
options of DSS and water ballast – individ- ually or combined – add a level of learning
54 SEAHORSE
complexity about the best tools to employ and in which conditions. However, the overall hull and appendages are designed to be reasonably non-critical, so the crew should never feel they are sailing on a knife-edge and wondering if the rudder is about to let go – or that they are falling out of too narrow a groove uphill. Sea conditions are a major factor here –
deploying the DSS foil will always have a motion-dampening effect but this has to be traded off against the added drag, even though the sails will be working way more efficiently. At other times adding the sheer mass of the water ballast is what’s required to add some momentum to the boat in an awkward seaway. Righting moment is usually king,
headsail option which actually reduced the rating for the equivalent very large headsail that would have been the previous situation. This sail is ideal for these fast line honours big boats and fast foiling-assisted designs. From the feedback and uptake in 2021 we are currently assessing the rating impact of this type of sail for 2022. Dr Jason Smithwick, rating office director
though, and as soon as we are on pace and the wing is providing as much as we can ever use then the water becomes redun- dant; but there will always be some areas where we can exploit both. There is a lot to trial and analyse. It would be nice to think with the tools
available these days that we can nail all this down in the design process, but funnily enough you still have to go out and sail the things to find out what really works… And this time we can’t wait. Hugh Welbourn, Totnes, Devon
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