- Matthew Sheahan
- Comments (1)
America’s Cup: Oracle’s New Pace Explained
An unexpected consequence of this America's Cup is that many of us have developed close relationships with our travel agents as the racing stretches out and we are forced to change bookings and travel arrangements on a daily basis. Strange though it may sound, the reason for this is that Oracle has learned how to tack their boat fast and foil upwind.
And one of the consequences of that, is that today could be another serious nail biter for the Kiwi team and its supporters.
For evidence of this take a look at the stats from yesterday's race, in particular the minimum speed through the tacks. The Kiwis boat speed bottomed out at somewhere between 12-13knots through the tacks whereas Oracle was typically 11-17knots, a huge difference. Spithill's team is doing this by using their new found skills at foiling upwind, something that they can now do better than the Kiwis.
Not only does going faster through the tacks save time, but it opens up a broader range of tactical opportunities. But how are they doing it?
The answer appears to lie in the way that they are tacking. Often yesterday we could hear the call aboard Oracle for a ‘fast mode' out of the tack. To do this Spithill goes into the tack foil borne and sails deep enough out of it to make sure he keeps enough speed to stay up on the foils. Then, as the speed builds further he heads up to get back into pointing mode before the boat accelerates too much and brings the apparent wind forward too much. Look at the way that the advantage line shifts through the tacks with Oracle appearing to lose out after a tack before then gaining double the amount they lost afterwards as the bow comes back up at speed.
(We saw a hint of this yesterday when they went a bit too quick and saw the speed peak at 37 knots upwind!)
According to what I'm hearing, the decision to foil upwind is one that was taken very late in the Oracle campaign, but now they are learning fast and can out perform the Kiwis uphill. I'm also hearing that you sail these boats as if they have distinct gears rather than a sliding scale of performance for a given true wind angle. In other words you can't trade a couple of degrees for a few knots it's either pop it up or sail in displacement mode. Typically two of these gears might be 22knots boat speed at 40 degrees true or 30knots boat speed at 48 degrees true, the latter being the filing gear.
Having learned how to do this and knowing that there is very little between the boats downhill, Spithill and his team have been able to put even more pressure on the Kiwis.
Today's forecast was for lighter breezes but the wind has been blowing hard all morning and there's a suggestion that we'll have similar conditions to yesterday ie. Breezy.
Having slept on this and woken to a misty breezy morning, the next thing that struck me was to phone up my new best friend at the travel agents.
More news later.