Ainslie watchers (and rivals) will recognise the signs… A modest, sometimes poor start, followed by stabilisation and then the big finish. Land Rover BAR did themselves a lot of good by winning at home, in turn taking the overall lead in the America’s Cup World Series. The top three in the ACWS have now moved well clear – BAR, Oracle and TNZ. Artemis remain the dark horse, down in fifth overall; but evidence suggests Sweden’s team are now simply focusing all their efforts on the only boat and race that matter
enter the start area from either end of the startline five minutes before the start, and head towards each other. The boat on port tack obviously had to keep clear of the starboard boat and the usual result was that both boats would end up head to wind in a dial-up. From there it was an arm wrestle where one boat or the other would extricate itself from the dial-up and gain control of the situation.
This worked OK when the boats only travelled at 9 or 10kt, but now the catama- rans can enter the start area at 30kt+, so a dial-up is out of the question, and the star- board boat would easily hunt down the port tack boat. The latest rules now give the port tack boat a 10-second head start, and the boats may not enter the start area until two minutes before the start itself. Even with this head start the port tack boat is still vulnerable if she doesn’t enter up on the foils and her opponent does. Once across the startline it’s a ½-mile drag race on the reach to mark 1. At mark 1 the boats bear away onto their VMG angle and the leader will almost always hold on until he reaches the boundary. The trailing boat has the option to gybe away, but this costs distance and she runs the risk of having to make one more gybe than her opponent on the run to the leeward gate. Again there has been a big change in the course geometry compared to the mono- hull days. Then if you were behind you were obliged to follow the leader around the leeward mark, then tack off in the hope you could generate some leverage to gain from any potential wind shift. A compe- tently sailed fast boat could guard against this by covering assiduously.
For the multihulls there is now a down- wind gate; the trailing boat can and normally will pick the opposite mark to the leader and leave the leeward end of the course on the opposite tack without losing
ground, so the vital separation is handed to him on a plate. Once again the boats will head out to the boundary, it simply costs too much ground to put in a covering tack, unless it’s crystal clear that you have chosen the wrong side; the distance lost in each tack is now huge, your bottom speed in the tack might easily be half your top speed so the golden rule upwind is to absolutely minimise the number of tacks. Here the unusual behaviour of the foil- ing boats really comes into play, they have a very wide and flat upwind lobe to their polar curve. Simply put, you can sail with one hull in the water and point up to tack- ing angles that are near 80°, or you can sail free and fast on the foils at a tacking angle closer to 100° and achieve the same VMG. This is a major part of managing the upwind leg: if you can get to the windward gate taking one less tack than your opponent you will make a substantial gain. There is also a gate at the windward end of the course so the opportunity to separate is there again. Down the run the courses set during the test races were about half a mile wide and once the breeze is in double figures this means you need only one gybe at the bound- ary to get to the bottom of the course. Now that there is just one gybe to be had on the leg to the finish, it’s high- pressure stuff, and in several of the closest races the leader slipped off the foils during this last gybe and the lead changed hands. It’s a different look for the America’s Cup: eight miles of racing in 20 minutes, with the lead easily changing hands two or three times a race, dips and crosses with a closing speed of 60kt, four or five races in an afternoon. It’s great, but it’s a young man’s game now.
Having glimpsed the future, how do we
prepare for this contest? First up, the rules allow us to choose a wide variety of daggerboard shapes for the race, mainly
characterised by different-length tips. Long tips lift the boat more easily at low speeds, but once the wind is up we don’t need or want all that extra weight and wetted area. But of course you have to make a call in the morning for races in the afternoon, so top of our priorities is the most skilful weather forecasting process we can iden- tify. Not only in terms of global conditions using the usual models, but also using bespoke tools to capture local effects. While Bermuda is a tiny atoll in the middle of an ocean there is land and vegetation, and the area where we race is landlocked and shallow. All of these geo- graphical features heat up and cool down at different rates and this affects how the atmosphere mixes up. So while you might think the island would see an uninter- rupted oceanic wind field the reality is somewhat different.
Having agonised about the configura- tion call for the day it’s time to get on with it. Traditionally the important call for a monohull race start was ‘which side of the course do we want to fight for?’, now it’s all about winning the drag race to mark 1. Most of this is about being on the line at full speed when the gun goes, or ‘starting on the B of the Bang’. As we have seen during the America’s Cup World Series, the skippers are already fantastically good at hitting the line even with no instru- ments. On the Cup boats we will bring any amount of computing power to bear. Can we calculate exactly when to ‘pull the trigger’ to hit the startline at exactly the right time? Can we predict which side of our opponent will give the quicker route to mark 1? Yes, we can do these things, but only if we can make a reasonable estimate of the wind speed and direction as we twist and turn in the starting area. There is some quite funky geometry involved in calculat- ing the true wind from an apparent wind measured while you are travelling at more than twice the wind speed.
So now you’re off into the race, charging towards a boundary that the TV audience can see but you can’t. There’s a number counting down or a boundary light flashing that you need to keep an eye on while nudging the board rake controls to keep the boat flying steadily, and steer- ing to stay in sync with the wing trimmer. This can all turn easily into information overload, and that’s why we have now engaged with BAE Systems to develop a Human Machine Interface (HMI) that draws on best fighter plane practice. I could go on but there is no doubt that
the new America’s Cup Class yachts and racecourses have massively altered and expanded the skill sets needed to get these boats around the course. It’s a fantastic new era where if you want to stay at the front of the pack, in addition to the tradi- tional naval architecture skills, you need to be on top of hydraulics, pneumatics, electronics, software and control theory. Not to mention that Human Machine Interface…
SEAHORSE 51
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