A Wing and a Prayer

© Courtesy Bora Gulari

Moth champion Bora Gulari tests his new wing sail.

In early 2010, both Gulari and May had come to the conclusion that the next big development in the Moth class would be a solid wing, similar to those seen on BMW Oracle’s trimaran in the 33rd Americas Cup. Both set out to build wings. May debuted his in August; Gulari’s emerged in October. Object 2 built two more wings, one for George Peet and one spare. May’s wing has two main elements, while Gulari’s wing has two main elements with a flap attached to the main element. Since May is the class's chief measurer, the Moth Class Executive Committee (less May and Gulari) was asked to interpret the rules to confirm the legality of the wing and determine how to measure them.

The class response was issued on August 12, but not published until November, and it created more questions than answers. Rather than rule a wing of any configuration as a single sail, the class deemed that a two-element wing is not just one sail, but a combination of a mast and a sail. This should allow May’s wing to compete, but what about Gulari’s? Here’s where the controversy gets interesting. If Gulari can prove his wing, with two elements and a flap, is a two-element wing, it should comply. However, if the class deems his wing as a three-element wing, then, as the committee stated, “the IMCA Executive Committee has discussed these types of sail/mast combinations and is of the belief that under the current class rules these would either be illegal (due to not satisfying the one sail rule) OR would have to be measured in their entirety as sail area.”

This vague ruling caused a division within the class, with the anti wing camp—which includes builders of the some of the current Moth hulls—trying to ban the American wings, claiming they violate the one-sail rule and the spirit of the class.

The debate focuses on the definition of mast. Class Rule 8.1 states that “the overall length of mast shall not exceed 6250 mm.” The second element of a wing would then be considered the sail, constrained by Rules 8.3 (“The distance between the bands (effective luff length) shall not exceed 5185 mm.”) and Rule 9.1 (“The boat shall carry only one sail when racing, with the total sail area being not greater than 8.00 m2.").

Based on a strict interpretation of these rules, it’s conceivable that a wing could be built with the first element one meter larger than the second element, creating a lot of unrated area. Rumors abound that Australians John Harris and Dave Lister were designing a wing that would take advantage of this loophole, but the wing will not be coming to the Worlds in Belmont. Both May and Gulari were aware of this potential loophole and agreed to build wings to the 5185mm height and a total area of 8m2. The real contentious issue with Gulari’s wing lies in the flap that is part of the first wing element. Some may see this flap as a non-structural piece that is allowed to deflect by aerodynamic forces. Since it doesn’t support the sail and produces lift, it must be considered a sail. Gulari disagrees, reasoning that, since there is no visible gap between the leading edge element and the flap, they must be considered as a single assembly. Since the class already allows camber inducers in soft sails, it would be counterintuitive to rule against similar camber-inducing mechanisms in a wing sail. Gulari further notes that, should his wing be deemed as more than two elements, the last paragraph of the rule interpretation allows for the wing to be measured, provided that the entire area is used in the calculation.