Jul 22, 2012

ETNZ AC72: Trickle UP

Left, still from a Sail-World video and report. This is really a case of upwards influence from the beachcats to the elite  big cats. The Cirrus R is currently the most extreme and radical design in the F18 fleet. The Nacra 17 was MM bid for the Games and took the spot. Photos CirrusUsa & Pierrick Contin

The Cirrus has prove to be a performer wining the Eurocat 2011 and being 2nd at Balaton. Also continues good performance from Heemskerk-Tentij and Casey-Tebo in the US.

The Nacra 17 with curved boards and designed specially for the Olympic trials, although using the Infusion/F20c heritage at large, also features a somehow raised forward rocker. But didn´t show yet any marked performance edge (still much to sail/trim). I compared its rocker with the Infusion and the aft 3/4 is identical or quite similar, for ie not following the extreme negative rocker of the Cirrus R.

Pete Melvin is part of the ETNZ design team and also talks about how small cats developments are taken in account at the highest level, check Jeremy Leonard interview on the AC72 launch here http://www.sailrevolution.com/ac-news/the-big-launch

At first glance you reduce wetted surface and displacement and possible better smoother tacks. The Cirrus R has a confirmed, even by the competition, and edge downwind, but we can assign that performance mainly (in my view) to their super flat fat bottom among other features including the mentioned radical negative rocker, see below and label "Cirrus R"  for more info.
Will try to get Manu Boulogne to see what they tried to achieve.
Also check comparison below with the fastest boat I've sailed up & downwind, the Hobie Wildcat.
I will test John Casey Cirrus R at LA for sure, but at least in the F18 different kind of design ideas have not shown yet any definitive advantage for any to be untouchable, so for now I will stick to more traditional lines for the Open Project for ie. Later I will take a look at big flat Cirrus R transom, a concept I use with added channels in 2007 for the RC16 that works quite well. Michele Petrucci from Bimare is also testing on a proto at home with some nice planning vid already.

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