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McGyver

Iceboats from the FP

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One thing that called my attention watching the iceboats racing is the curve of the mast.  In my experience, being boats or airplanes, one tries to have the straightest edge facing the wind. (Ask the TP52 that are reaching 8 tons of tension on their backstays.)

Can any aerodynamicist out there explain to me why those iceboats have such bendy masts?  Or is it lens disortion?

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Looking at the way the mast responds to gust I think they are using the bend to auto trim the sail. Similar to the way a square top main works. From a steady state aerodynamics perspective you are right that a straight mast would be fastest.

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It is not lens distortion and it looks even more impressive when looked at from the boat. As to why it might be fast, there are a couple of things I've thought or read about. The DN is pretty over canvased so with stiff masts when a gust hits, it pops into a high hike and the sailor is forced to dump power, etc. to get back down. Bendy boats just accelerate through the puff with much less drama. Also there is no mast rotation limiter on a DN. Stiff masts could over rotate at high mainsheet tension which turned the mast 90 degrees to the sail completely boarding out the sail except for the 4" mast now sideways to the air flow. This is not a fast shape. The bendy masts stay in line with the sail better making for a much faster shape. But why is it only done on DNs?

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