Ben
Probably vortex shedding off a bluntish trailing edge or flow detachment on a control surface. It does not always mean higher drag. In high speed applications it can be used to reduce drag as in the cases of the rudders in the Gerr reference previously linked. The vibration results from the supporting structure getting in tune with the shedding. So you have to avoid the vortices or stiffen the structure to eliminate the vibration.
Rick
On 04/08/2010, at 9:22 AM, bjarthur123 wrote:
>I seen speed recorded on my gps unit of 12mph sailing on the outside open ocean with no problems just some vibration and humming.
i've heard such humming on my Weta and a Farrier that i crew on when going at similar speeds. everyone gets excited when this happens because they think it means we're planing. perhaps it's correlated, but i'm thinking that it's really due to the foils cavitating. true? if so, that's bad, right? more drag less lift?? short of replacing the foils and/or slowing down, is there anything i can do to stop it?
ben arthur
weta #358, "gray matter"
ithaca, new york
Rick Willoughby
03 9796 2415
0419 104 821
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