To clarify, that should be a sharp trailing edge, just as Jerry points out, the edges are not rounded. The quote was from the book. I took that to mean the side of the rudder near the trailing edge, not the edge itself. The bottom paint thing stands.
Howard On Sep 27, 2008, at 9:47 AM, Howard Audsley wrote: > 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) >> >> _______________________________________________ >> http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats >> > > > _______________________________________________ > http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats > _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats
