Catching kelp between rudder and hull on PSC 34

[mondofromredondo]

Hi all,
I have a problem I've that appears to be somewhat common on 1988 era PSC 34. When sailing thru areas prone to kelp I often have a piece of kelp become lodged between the top of the rudder and the hull. It is quite a nuisance as it places a load on the helm because of the friction it creates when turning. Has anyone come up with a solution ?

Thanks
Keith
1988 PSC 34