Jonathan Ganz wrote:

I had an illegal head on my Cal 20. For that boat, I cut out the fitting,
then somewhat closely matched a piece of wood to the hole. Then,
filled in the gaps with 5200, then glassed over the whole thing from
both sides. I don't know if that was the best way to do it, but it
doesn't leak and I suspect it's stronger than the rest of the hull.

Is there another method that's as or more effective?

Sure. Just fiberglass over the whole thing, then fair it.

I filled in a thru-hull in our tugboat this spring, which gave an opportunity
to check the hull lay-up (3/4" thick) also. Using a side grinder to create a
hollow area inside & out, then I taped a piece of wax paper over the outside
of the hole, then used WEST system resin & low density filler to fill the
hole, then put three layers of 28oz cloth with bonding filler on the inside.
Then I put on another three layers of heavy cloth plus some lighter stuff,
and used the side grinder again to smooth it over. There is no doubt that
this patch is stronger than the rest of the hull, and thoroughly bonded.

Here is a picture of the inside of the finished patch. That yellowish thready
on the left
http://community.webshots.com/photo/...73346002sUSTvu

A side grinder is a GREAT tool, but I used up a lot of expensive masks &
respirators (to protect my even-more-expensive lungs).

Why did you use 5200 inside a layer of fiberglass? Why not just glue the wood
in place with resin? BTW it's a good idea to cut away a tapered area around
the hole for better bonding.

Fresh Breezes- Doug King