I have the original solid mahogany rudder that came with my 1978 M17, but also have a fairly new replacement that I got from Bob E. and it is also of the solid mahogany type. The new one came with a clear finish that has help up for the past few years, but is now fading and needs to be touched up or replaced. The entire rudder was coated with this finish. Almost ALL clear finishes specify they are not for use below the waterline. If the boat is trailer sailed, I presume a short dunking of a few days doesn't hurt and a person could use one of the polyurethane finishes such as Interlux Goldspar.....that is what I use on my tiller. Somewhere around 7 or 8 coats it starts looking like it was dipped in glass. But if the boat is left in the water for weeks or months on end, what then? For the old rudder, I sanded off all the finish and paint, repaired some damage, then glassed it to a few inches above the water line. That got several coats of epoxy over the glass cloth, and was then hit with a hard finish bottom paint. The problem with glassing it and sealing it up, if water ever does get in, it stays in. So what is the recommended coating for these solid mahogany wooden rudders?