Tuesday, May 29, 2012

Going Geek

Late April upwind-downwind sail to Pt Pinole through the Carquinez St. I'm going all geeky on this post and including the GPS speed data for the trip. These numbers will be boring for most folk, but are interesting to some sailors curious about the relative performance of the Tiki. This was a (rare) perfect sunny day with a 10+ knot westerly breeze and complimentary tides (sailing out with the ebb and back on the flood tides). The numbers show that we made 9 knots tacking upwind with 1-2 knots ebb tide assisting - this reinforces my experience that the Tiki will reliably make 7 knots to weather with full working sail and ideal breeze. The data is corrected over ground speeds in knots using the free software GPSAR. The red numbers are upwind speed, and the yellow is downwind.


An interesting thing looking at the downwind numbers is that the Tiki is faster to windward than it is running dead downwind with the working sails, although the VMG (velocity made good) is obviously better on the return because the boat is heading in a straight line to the destination instead of tacking. Upwind VMG to Pt Pinole ranged from 2 - 5 knots. Thirty nautical miles this trip.


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