Rudder vibratrion

[taimer]

I am using a drop rudder on my flying dutchman because of very shallow water for
100 metres offshore from our launch point.

The rudder vibrates very badly and a junior sailor commented unfavourably yesterday about "you got a motor on ther mister?".

What are th known causes of rudder flutter?

The fixed blade rudder has no such problem so I am discounting the centre board.

The blade has a 3mm flat tailing edge.

I am exploring the possibility of the following.

Loose pintols.

Preventing rotation of the blade itself in the two side ''cheeks''

Tightening the rudder blade pin so it will just move.

Sloppy pintol fitting on the pintol pins.

I would apprciate comments from anyone who might have some ideas and/or has cured a "singing" rudder before.


thanks


Tony Aimer

[Sailormon6]

Tony, it sounds like you have thought of most of the possibilities that I would suggest. I would only add that rudder vibrations often result when turbulent water moves past the surface of the rudder. You should look for anything forward of the rudder that might be generating turbulence.

[Jeff_H]

Often that kind of vibration is caused by an out of fair or an assymetrical foil. It can also be caused by an improperly shaped foil or one with too flat a camber.

Jeff