Friday, August 8, 2008

Velocitick, tick, tick...

Velocitek has posted the GPS tracks for the two fastest runs at Weymouth. While there's no true wind direction shown, supposing the two tacks are approximately at the same angle to the wind direction, it's easy to measure the true wind angle. Tracing the tracks, approximating each with a straight line, pulling out the protractor I measure the jibe angle as 110 degrees. Making a couple of subtractions yields a TWA of 145 degrees. With a true wind speed of 25 knots and a boat speed of 25 knots, a little trig yields an apparent wind speed of 15 knots at an angle of 72.5 degrees off the bow. Interesting, but completely useless. If you're trying to get the highest speed, you're going to be heading in the direction that makes the sail plan most powerful and the boat most controllable -- higher in the lulls and lower in the puffs. If you're racing on a reach you need to get to the mark, whatever its heading. If racing downwind it's the VMG that matters, not the boat speed. Of course, the Velocitek can calculate the VMG given a wind direction vector.

Speaking of Velocitek, my S10 unit seems to have given up the ghost. It's a shame because the S10 is much smaller and lighter than their current SC-1 unit. But however light it may be, right now it's dead weight. Elaine Ryan at Velocitek said their two year warranty will be honored, even though they have stopped supporting the S10 model. She's offered to cut a check refunding my purchase price of the S10 ($199) or to give me a $250 discount on buying a replacement SC-1. I haven't decided yet on which option to pursue, but the refund will help knock down a bit of the Weymouth debt.

Speaking of debt, Scott claims an out of pocket expense of Australian$27.5K on his latest moth campaign, not even counting $11,000+ in sponsorship. Makes my complaining looks sorta weak. He's also got his take on the moth as an Olympic class, an interesting perspective. I've added his blog to my list on the right.

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