Leaking Rudder is common
This is a common problem for foam cored rudders. There are many posts in the archives about this, but I have time on my hands so I will impart what I know here.First on an ounce of prevention: When the boat is out of the water, remove old bottom paint and re-apply with a white bottom paint. A dark bottom paint absorbs heat (even in the water) and this is the #1 cause of delamination of the fiberglass from the foam core - the rudder getting too hot. The rudder OEM also suggests covering the rudder in white plastic when the boat is on the hard.Next, moisture saturation: Did the surveyor say the rudder was saturated and/or had a high moisture reading? If so, then the repair is to remove the rudder, grind off all the gel coat, and bake under heat lamps (not too hot!) until the rudder is completely dry. Then re-gel coat. There are many variation on this, but if you want a completely dry rudder this is how most pros would do it.Finally delamination: When the fiberglass detaches from the rudder's foam core, you can re-attach it using a "penetrating" epoxy. This has to be done with the rudder off the boat. Trace the perimeter of the delam area and drill holes evenly spaced 1 & 1/2 - 2" apart 2" in from the edge of the delam area. Depending on the size of the delam, drill holes in concentric cirles towards the center of the delam area spacing each circle of holes around 2"-3" apart more or less. Next pour epoxy in the holes starting with the outer holes and moving in. When the expoxy rises out of the holes with hand pressure applied, that is enough epoxy. Fashion a press out of a couple of sheets of plywood, and using woodworkers clamps apply pressure to the delam area while the epoxy sets. Don't forget to put something between the plywood and the rudder so you don't wind up epoxying the plywood to the rudder! I used a heavy plastic sheet as a buffer.Sand off excess epoxy and re-gelcoat as needed.On the repair itself my thinking is this: A new rudder is mucho denaro. Repairing the rudder can take a lot of man hours, but is sweat equity. Ignoring delamination or water penetration will hasten the demise of the rudder. Properly maintained and repaired on a timely basis as needed, the rudder should last the life of the boat more or less. Good luck.Mike