Twin rudder vibration

[Kochi]

I have a strong vibration through the rudders on our Beneteau 21.7. Has anyone else suffered this? Is it simply a case of changing the washers and bushes?

 

[Boomshanka]

etap21 can do the same... Usually at certain speeds which suggests resonance (sp?). The only cure I've heard of is to very very slightly turn the rudders in towards each other... But I've no direct evidence that it works or what the consequences are

 

[ianat182]

Don't know if this is the same but on high speed sailing dinghies this vibration is related to the fairing of the rudder blades themselves. The fix is to plane a square edge to the trailing edge of the foil no more than a 3mm width , so as to allow the flow to break off cleanly from the trailing edge. Can apply to centreboards too.

 

[oldsaltoz]

Adjusting rudders to tow in on a mono hull will do nothing for performance of holding a good line however, on a catamaran it is all but compulsory due to the distance thay are from each other.

I suspect the problem is related to the flow over the rudder/s.

Hope this helps.

Avagoodweekend......