HiFolks
I have a Hobie 14T with EPO rudders one of which moans between 7 and 12 knots. Over that the noise fades but it gets pretty loud at times. I sail in an Estuary which has worn away the rudder tips a bit. Also I note from the hobie site that the original rudder pins were nylon rod. I have replaced the rather warn alloy pins that were on the boat with stainless tube and shimmed the rudders so there is very little movement. None of these measures has had made a huge difference. Could also be a slight parralell problem which is difficult to adjust as the crossbar fittings are pretty coroded in place. With so many variables I wonder if anyone has hands on experience with this problem? Regards
Paul

Paul,

That is a common problem. The trailing edge of your rudder needs to be filed. When fabricating the rudder there is a minute "bulb" that is sometimes formed along the trailing edge of the rudder. When in the water and at the proper speed the rudder vibrates and sets up a harmonic wave which is the "hum" that you here.

On the Hobie web site look under "help with repairs" and "frequently asked questions" there are numerous posts on this subject.

When you do work on your rudders be EXTREEMLY careful with your EPO's. There is not a lot of material to work with.

John

Here is a rough sketch of the issue from the Hobie support area:



The old EPOs are pretty thick on the trailing edge and don't have the bulge shown in the diagram above, but the idea is the same. The new EPO2 blades were re-shaped to help this issue and have a thinner trailing edge.