IMOCA Open 60’s – how are the old boats going to compare with the new?

IMOCA Open 60’s – how are the old boats going to compare with the new?

Sunday October 27 2013 Author: Owen Clarke Design Location: none selected

Normal 0 false false false EN-GB X-NONE X-NONE Since last weeks’ IMOCA meeting considerably more information is available on how 60s designed to the new rule will be different and might compare to existing designs. The rule changes are preliminary until published and are to be subject to a further meeting in December.  But there is now light at the end of the tunnel and by the middle of December design offices, if they haven’t already started, will certainly be in a position to both commence design and compare performance of the old boats verses the new.

The class does seem to have acted to protect the interest and competitive lifespan of the existing fleet, as well as improving safety and reliability (which inevitably reduces both risk and costs) by two well made and important decisions; the standardising of mast and keel designs. Given the numbers we’re seeing the position of older generation boats is encouraging for those teams who either because of funding or limited working up time are looking at buying existing later generation IMOCA 60s for their campaigns.

In respect of the new keel requirements, our existing highly modified design Gamesa, with its light weight 470kg carbon fin will be obliged to place a 100kg counterweight, within 2m of the yacht’s center of gravity. This will in effect be low down, on the hull bottom, midships and will only increase her IMOCA measured weight to 8.16 tonnes.  This will have a negligible affect on righting moment (power) which was grand-fathered and remains higher than the previous maximum introduced in the 2008 rule changes.

All future IMOCA rigs (classic or deck spreader options) will have minimum weight and center of mass. The current Gamesa rig is within 1kg of the newly established mass and 100mm of the vcg. This sounds as though the existing boats may have no advantage here, but that’s not the case since under the new rule Gamesa’s righting moment (an example of one of the high righting moment, moderate displacement boats) is 22% greater both upwind and downwind than the maximum righting moment of 22,000 kgm at 25 degrees, being allowed to all new designs. It appears that the newer boats will have rigs that are less loaded than the old, but the equivalent weight of the lightest of the existing rigs. On the face of it, a positive in terms of reliability (providing loopholes don’t remain open to reduce drag which might introduce its own problems) but little or no advantage in terms of performance for the new designs.

Existing boats such as Gamesa, Aviva, and Acciona will all carry forward (because of grand-fathering) innate characteristics of their design which are not available under the new rule. These include the use of interceptors (not Acciona), lighter adhesive glue film and having been constructed predominantly from Kevlar honeycomb core, which has been banned in the future, but is 20% lighter than Nomex

In reality, time is now short to construct and prepare for the Barcelona World Race (impossibly short for a Route du Rhum entry), unless one were to build from existing moulds in France or  Acciona’s in New Zealand, which is certainly still the most cost effective country in which to build one of these boas. Later generation 60s are of course available for charter or purchase and these lastest IMOCA rule changes and grandfathering seem to ensure that the fleet remains very close in performance.

Owen Clarke Design broke into 60’ design at the very beginning of the adoption of the first IMOCA rule in 1999, with the ground breaking Kingfisher. They were the first to introduce many of the innovations that still exist in the IMOCA class including masthead rigs, halyard locks for code sails and jibs, triple headstays, central ballast and the banned interceptor system. Their 60s have won the single-handed classics: Route du Rhum, OSTAR as well as the single-handed Vendee qualifying race, the BtoB.  Round the world honours include podiums on the Barcelona World Race and the Vendee Globe. The elusive Vendee Globe win remains a driving force for them as designers.


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