Seahorse March 2000

Seahorse March 2000

The semi-finals of the challenger series are over and now it is down to two teams. It seems like a very long way since the beginning of the series, when everybody. was measuring the performance of each individual team. Boats have been radically improved through the series, some of them going through major surgery. During most of the races the speed of the boats was very close and definitely not enough to overcome the tricky conditions of the Hauraki Gulf. We came up with the fastest boat downwind and probably one of the fastest upwind on relatively flat water.

But it was not enough , which shows the importance of upwind performance as opposed to downwind in these types of races. Boats spend more time upwind than downwind, so any speed edge a boat may have upwind is multiplied by the longer time it sails in this condition. Not to mention the tactical difficulties of passing a boat downwind. In fact, altough substant ially faster downwind, I only remember actually going past a boat once in 102 downwind legs. The modifications we did for the semi-finals were a logical development, based on the new family of appendages from Round 2. Overall it comes down to five generations of winglets and three of rudders, with two generations of keel and bulb. And I think there is still a lot of work to do!

The over-rotating carbon headfoil we managed to use at the end was very effective: not only was it 10kg lighter, but it also allowed us to play a lot more with the depth of the genoas. On the other hand, the behaviour of the boat in dynamic phases, such as tacking or simply sailing through a specific wave pattern, are certainly aspects we did not handle very well. This opens the door to extens ive research for the future, as I feel we are only j ust starting to understand the dynamic behaviour of these slender but overpowered boats. We will keep improving our boat as much as we can, and as such the bow is being replaced which will allow us to keep up development at least until the end of the Cup. The more we improve now, the higher our starting point for the next challenge. Arriving in Auckland in September, a lot of people thought we had pushed slenderness too far and that our boat would simply not perform upwind due to lack of stability. Today I am convinced this statement is wrong, as our best performance (excluding pure sailing talent) was in a breeze. These boats have very heavy displacement, and the advantages of slenderness are huge, certainly even more in constantly changing conditions as in Auckland. In low winds the advantage of a narrow, low-resistance hull is obvious. If the wind picks up to an overpowered situation, reducing t~e sails’ power and handling their thrust are more important than having extra hull stability, as you can always manage to keep speed up due to the low resistance and dynamic stability.

The problem lies in the transition period, somewhere in between 12 and 15 knots’ true wind speed . A narrow boat will make the transition from underpowered to overpowered earlier than a wider boat, giving the latter an advantage in being able to keep the sails at full power for longer. Look at Stars & Stripes: she was probably the best-sailed boat of the series but, compared to a narrower hull, was ‘slower’ in light winds than she was ‘faster’ in the breeze.

Also, it takes longer to do the same distance in low winds. The Kiwis will face the same problem against either Prada or AmericaOne. Under 15 knots, they will have to excel to win. Having said that , 12-15 knots remains the mos important range to optimise for. A disappointment of the semi-finals was the lack of speed of America True. Lightening the boat and changing the appendages did not help much. This shows how easy it is to get seduced by numerical solution. We made the same mistake at the beginning. Computers can only get you as close as 1.5-2.5 percent accuracy in performance prediction. This is nearly three minute around the course! Obviously not close enough, the rest is down to human ingenuity and common sense. But here we are at the dawn of ave deserved and obvious final. If you had asked anybody four months ago who the favourite challengers were, the answer would have been Prada and AmericaOne. Prada still shows good speed and sometimes impressive tactics, especially when they came back from nowhere to finish a few seconds behind AmericaOne during their might semi-finals clash. On the other hand, I am not very impressed with the small progress in speed they’ve achieved since October.

AmericaOne has been sailing USA-61, their newest boat, which shows very even speed upwind crucial in allowing them to sail faster when going for speed, while also keeping speed up when sailing in high mode. Not to mention the capacity sometimes maintain a weather position in a head But the final will not be about boat speed . It will be about sailing better than the opponent, and by sailing I also mean handling protests and the psychological pressure. It has been great racing so far and it can only get better. Well done to the finalists. The America’s Cup’s future looks bright, with three continents, battling for dominance, a true sailing grand prix at last!