Vibration under Sail just over 4 Knots

[Autonomous]

I sailed a vessel with an absolutely blunt barn door rudder that had a wiggle sensation at ~ 4kt. No actual hum though. The physics are fascinating.

 

[shaggybaxter]

Interesting, didn’t know you could get rudder hum at low speed. I used to use it as a toe in guide for dual rudders that already had an asymmetrical trailing edge chamfer. You could tune it in and out depending upon the average speeds you were doing.