Optimum Pumping Techique

   Thanks for that.  That's a good point about combining with rocking - that forces the pumping frequency to coincide with the roll period.  But on windsurfers do you just pump as fast as possible or is there a rate that feels fastest?  And could you improve speeds by a fraction of a knot if there was proper research into it?

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Guests Send Private Message Find Member's Posts Guest Group	Post Options Post Reply Quote Guests Quote Reply Topic: Optimum Pumping Techique Posted: 06 May 18 at 6:50am
	Thanks for that. That's a good point about combining with rocking - that forces the pumping frequency to coincide with the roll period. But on windsurfers do you just pump as fast as possible or is there a rate that feels fastest? And could you improve speeds by a fraction of a knot if there was proper research into it?

iGRF Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6499	Post Options Post Reply Quote iGRF Report Post Quote Reply Posted: 05 May 18 at 10:11pm
	Well it's slower than we use when windsurfing, because the sail refresh rate is not as efficient. Depending on the style of pumping action, I.e if you can combine rocking the boat to leeward in order to assist the refill or not I'd say pumping a dinghy is only about 60% as efficient as pumping a sailboard. This research is of course pretty anecdotal, since the natives don't actually like it up them, so peak efficiency can only really be achieved when races get abandoned. PS And don't even sneeze into the sail down the lake or the miracle mums will scream and rant about waving their arms in the air..
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Guests Send Private Message Find Member's Posts Guest Group	Post Options Post Reply Quote Guests Quote Reply Posted: 05 May 18 at 9:29pm
	Does anyone know of any published research into best pumping practise? I'm thinking particularly about the frequency and amplitude of the pumps. I think the combination of the frequency and amplitude should be such that the Strouhal number should be around 0.2 - 0.3 (Strouhal number being frequency x amplitude / apparent wind speed), but that still leaves a trade off between frequency and amplitude of the pump.