Sailmaking Joins the Design Loop

By Robert Hook

From the time of the ancient mariners, sailboats have been built from the bottom up, and the sailmakers have been the last to get involved, which limits our opportunity to improve boatspeed. That changed with the AmericaOne team at America's Cup 2000.As designer Bruce Nelson was developing hulls, Michael Richelsen (creator of North's design system) and I were analyzing the optimum sail shape for those hulls and giving him back new force tables¿letting him know how much power would be supplied. It was an interactive loop¿all those flatter sails were a by-product of the narrower boats. We had determined, using the velocity prediction program, that narrow boats could work if the sails could be flattened out to reduce heeling moment. The only way to flatten the sails was to increase rig stiffness.That meant we had to work with the sparmakers at Omohundro to link our aerodynamic analysis with their structural analysis. We provided detailed rig loads; they provided us with detailed structural properties of the mast. Long before we'd ever built the mast, sails, or boat, all three builders had very strong ideas about what the other people were requiring.Interestingly, Team New Zealand developed sails that were quite full compared to Prada's and AmericaOne's. This was a result of their own analysis of the shapes required to optimize their new boats, which were larger boats with significantly less sail area.Of course, the teams with fewer resources couldn't work through this process, so along the way you may have seen a little bit of catch-up. At Auckland you didn't see Stars & Stripes fly a flatter main until the semifinals.Wait a minute, you say, there was a North Sails person with almost every team in Auckland: Mike Schreiber with America True, Guido Cavalazzi with Prada, Dave Hirsch with Stars & Stripes, Burns Fallow and Mickey Ickert at Team New Zealand. Tom Whidden, president and CEO of North Marine Group, was tactician on Stars & Stripes. Didn't they all know what the other North people were doing?The simple story is that I was there to help my own boat win, so there was no motivation for me to discuss things with other members of my company, and they felt the same way. Cavalazzi was more a member of Prada than he was of North Sails. I considered my first loyalty to be to AmericaOne.Later, of course, all of the details will become known to all of our designers. For the sport's sake, that's how it should be.