First I'd heard of this was in "Royce's SAILING ILLUSTRATED, Volume 1", bottom of page 134. "The trailing edge of the wide rudder at force 3 vibrated considerably, which eased when it was rounded. We had a similar vibration which disappeared after the edges were sanded. When new bottom paint is added, our rudder will vibrate for approximately a month, then stop". I have noticed the same thing with new bottom paint. If you think about it, the vibration is likely caused by a harmonic of some subtle cause of unbalanced lift on one side, which breaks down at some point, allowing the flow to force the rudder back to it's trailing aspect, lift is generated again, etc. Inspect your blade and/or run your hand over the trailing edges to see if you can see or feel any subtle bumps in the varnish or edge. If you find one, sand it smooth. Look at it under low light conditions, shining a flashlight down the edge. Shadows will appear if it's not perfectly smooth. They do not all do it. Howard On Sep 27, 2008, at 2:20 AM, James Poulakis wrote:
Sailing even with a moderate breeze makes Spirit's rudder hum loud enough to drown out the Pillar Point fog horn. The rudder is new and doesn't seem to be warped. Is there a trick to stop this or is it just a Monty thing?
Jim Poulakis "Spirit" (M17)
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