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CupInfo examines IACC bow design evolution

Design expenditure probably accounts for 20-30% of an average America's Cup campaign budget. So, where does the design team start? Clay Oliver of Team New Zealand 2003 suggested they looked for a wholesome shape independent of the "no hollows" rule to build NZL 81 and 82.

It's safe to say decisions about the pointy end come early in the design regimen.

Since the IACC rule was adopted in 1989, designers have experimented with an increasingly interesting variety of shapes. There have been destroyer bows, meter bows, knuckle bows, and now state-of-the-art appears to incorporate an elevated stem dropping into a graceful knuckle.

Examples of destroyer bows include Tag Heuer’s NZL-39 in 1995 and Aloha Racing’s USA-50 in 2000. Most of the 2000 vintage boats had meter bows such as those of Louis Vuitton winner Prada.

For the 2000 defense, Team New Zealand raised the bar with the radical Laurie Davidson knuckle bow. A hull’s waterline length directly affects the boat’s speed potential. The Davidson knuckle design’s advantage over a classic meter-bow design results from extending the length of the sailing waterline without adding to measured waterline length under the rule.

When a meter-bowed boat like ITA-45 "powers up" the stern section is pushed down, gaining length aft. But as the long sloping bow rises, waterline length gained aft is simultaneously lost forward. When NZL-60 powered up her knuckle maintained contact forward, preserving actual sailing length.

One of the most interesting bows from 2000 was Bravo España, with her upturned nose. In 2003, the Alinghi design group looks to have incorporated some of the best features of the three generations in SUI-64.

A simple graphic of the shapes is on the right.

© 2003


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