28 August 2009

Fastest Shape?

Aerohydrodynamically balanced or skinny and low wetted surface? The Megabyte will steer itself downwind with just a slight heel to weather. Feels fast without any drag induced by corrective rudder action. With that slight heel, however; there's still a lot of flat aft section dragging along the water surface. Would it be faster to crank the boat way over to weather like the Laser sailors do? This would indeed reduce the wetted surface of the hull, but the asymmetrical shape would then need some rudder to keep on course. Last Friday, I decided to give "excessive" weather heel a try while out chasing the Fleet 76 Vanguards around. First challenge was learning the balance point with the boat that far over and close to capsize. The boat is definitely more prone to rolling when positioned up on its edge like that, but of course that's an indication that those big flat sections are no longer dragging water. I found that putting some firm pressure with my hand on the lee rail would quickly suppress a roll to weather. Good to know. As for speed differences? Don't really know--only had V15s to run down, and a Megabyte can do that without much trouble no matter what the boat's attitude.

An unusually strong ebb tide running counter to the prevailing wind, meant that the downwind legs were effectively much longer than the upwind legs. That worked to my advantage as I beat the Vanguards round the windward leeward course two out of three times.

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