Centerboard/Rudder Humming

I purchased DORKFISH, Hull 4909, in January and began racing it in March. When sailing upwind with a bit of pressure, there is a rather loud "humming" noise that is coming from below the boat. Is this hum caused by the centerboard? What else could be vibrating to such an extent to cause the hum? Any other ideas as to the caues? And any idea how to stop it (and redirect the energy caused by the humming into boat speed)? Tommy FS 4909

Comments

First of all - welcome to the Flying Scot family! I thought

First of all - welcome to the Flying Scot family! I thought I read something awhile ago on this forum about center board hum. Do a search on hum and you will find a topic started by Peter Hoeg (Oct 2004). Great replies including one by Harry Carpenter. Fair winds, Andy FS 4957

Andy, thanks for the response.

Andy, thanks for the response. I searched the 2004 and 2005 thread and read the suggestion - to file down one side of the trailing edge of the rudder to stop the vibration. Has anyone ever done this? Is it class legal to modify the shape of the rudder or the centerboard? Has anyone actually filed down one side of the trailing edge of the centerboard? Or of the rudder? Anyone had satisfactory results with either of these approaches - causing the vibration or hum to stop? Tommy

The hum could also be caused by a loose centerboard gasket.

The hum could also be caused by a loose centerboard gasket.

My boat (4222) does the same thing.

My boat (4222) does the same thing. In my case, I can feel vibration in the tiller, so it is clearly the rudder resonating. Harry carpenter told me to file down the trailing edge of the rudder on one side. I have not yet tried that as I had to rebuild my rudder head this week, and want to wait to see if I still have the problem. If it still resonates, I will try the filing and let you know what happens.

Well, my humming has gone away.

Well, my humming has gone away. I rebuilt the rudder head, which had cracked, and now that everything is tight again, the humming is gone. We had lots of wind Sunday, and not a sound from the rudder.