New AC33 Class Rule

Artist’s impression of an ACC V 5.0 yacht (left) compared to an AC33 yacht at similar scale.

by Daphne Morgan Barnicoat

The AC33 has been designed through consultation between the Defender, the Challenger of Record and the 17 other entered teams and the process was headed by Tom Schnackenberg as the class rule and competition regulations consultant for AC Management. Designers and team managers from the 19 America’s Cup syndicates met regularly in Geneva, Switzerland, and Valencia, Spain, since the design process began in early November 2008.

This group agreed to develop a boat similar in cost to the America’s Cup Class Version 5.0 boat, but with a more exciting performance. The AC33 Rule evolved to a race yacht of 26m maximum length overall, with 5m of draft and a displacement of 17.5tonnes.

The sail plan area is greater than with the ACC Version 5.0 but without overlapping headsails, and as with the AC90 Rule contemplated in 2007, the boat has a bowsprit and the spinnaker area is limited only by sheeting constraints, not by measurement of dimensions. Given the lighter displacement, the AC33 will be more demanding to sail upwind, and will provide sparkling performance on the runs. Maximum beam is 4.8m, which will seem wide to people used to the appearance of the Version 5.0 yachts, where the last generation of yachts had a beam not much more than 3m in many cases.

Tom Schnackenberg, class rule and competition regulations consultant for ACM, on how the process worked and what to expect of the new class:
“We have had a very active 10 weeks pursuing this new AC33 Class Rule. The process was very similar to that of the initial AC90, and we deliberately used many of the clauses already developed for it 12 months ago. Because of our previous experience, this process seemed familiar and ran smoothly, in spite of the interruption caused by the Christmas holidays.

“The boat was originally suggested as one with overhangs, and girth restrictions, (a sort of mini J-class) but as different designers got into the act, it quickly evolved into a boat defined only by the length overall, weight, max beam and draft. This allows simple measurement processes for the hull itself, and each change seemed to make the boat go faster!

“As it turned out, the boat is slightly longer than the ACC Version 5.0 boats and several tonnes lighter, with similar sail area and righting moment. It promises to have similar upwind speed and to have sparkling downwind performance.

“We think it will be a boat which the America's Cup community will really enjoy; a worthy successor to all the wonderful boats that have gone before.”

America’s Cup Defender Alinghi’s principal designer Rolf Vrolijk on the new class:
“For designers it is always more exciting to be involved in a new class or with a new type of boat than the highly evolved existing class where we can only focus on very detailed optimisation . It is quite challenging because it means starting from zero and this is a class like nothing we have seen before so if you do your homework right, you would be competitive. Some teams might be very competitive in some corners of the rule, so that will be very interesting.”

John Cutler, technical director for the Challenger of Record, Desafío Español, on how the new class can level the playing field:
“It is a clean sheet of paper and therefore everybody has a good opportunity to come up with and design a fast boat or possibly the fastest boat, so we think that this is a good opportunity for all challengers and it will work well for Desafío Español.”

Andy Claughton, design team coordinator for TeamOrigin, the British challenger, says:
“Creating the new AC33 Class Rule has been a terrific combined effort from Alinghi and the challengers. The vision of the boat was clearly established; it had to be fast, up to date and challenging to sail, whilst not being prohibitively expensive to build and campaign.

The rule development was done at a series of round the table meetings chaired by Tom Schnackenberg who brought all his experience to bear in guiding the writing of the rule text.

"All the challengers were able to make their voice heard, and the experienced members of the group have worked towards a rule that has many fewer constraints than the old Version 5.0 boats.”

Alinghi