Wave Hull Repair - Rudder Bracket

The six screws on one of the hulls holding the rudder assembly corroded and the entire assembly fell off. The screws are okay, the material around the screws corroded and left six fairly large holes in the hull approximately 5/8" in diameter & about that deep, but the holes don't go all the way through the hull. It is not taking on water. The bottom bracket (which has four screws) disfigured the hull in the vicinity of the four holes, and the surface is no longer flat for mounting a new bracket. What do I do?

How about cleaning out the remaining corrosion, fill the holes and build a new flat surface for the bottom bracket out of the same material used to fill the holes, drill, tap and remount the assembly. What should I use to fill the holes? Have any other ideas? Keep in mind the boat is on the beach and I don't have access to electricity.

fixing the holes is fairly easy. The disfigured transom surface is a little more worrysome.
To fix the screw holes drill them out to maybe 3/8 or 1/2". Mix some epoxy and fill them up with a syringe. You will need to be very carefull not to drillall the way through or you'll have a difficult time with the epoxy leaking into the hull. After the epoxy has cured, level them off with the surface, redrill the mount holes a size or 2 smaller then the screw size. I would use a tap to tap new threads into the epoxy but you could probably just use the srews to tap themselves.

Without seeing the disfiguration you mention I'm not sure what I would do. The transom might have become weak and could completely fail.
If it were me and it looked like it might be ready to fail, I would install an access cover in the deck to gain access to the inside of the transom inspection and possible fix.

I'm not too familiar with the Wave construction, but it may be the same as the fiberglass Hobies in that an aluminum plate is molded into the transom for mounting the gudgeons. A couple options come to mind.

First would be to move the entire rudder assembly slightly up or slightly down. Fill the old holes with silicone. Drill and tap new holes slightly above or below the old holes. As long as you drill into the aluminum plate, you should be fine.

The other option would be to drill and tap the existing holes to the next size larger (most likely 1/4"-20). You will have to drill the holes in the gudgeons to accept the larger screws.

The last option may be to install a porthole in the deck at the back of the boat. Then you could through-bolt the gudgeon screws with lock-nuts on the inside.

I'd stay away from epoxy, it's not going to stick to the polyethylene hull.

sm

I was wondering about the hull construction of the wave after I wrote the above. The fix I recommended was for figerglass hulls. You are right. Epoxy won't adhere well to polyethylene.