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Jonathan Ganz
 
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Default best way to patch a thru hull?


Thanks for the pic and the advice. I used the 5200 to make
sure I got all the gaps filled in, though I guess it was overkill.

I'm not sure what you mean about leaving a tapered area
around the hole. Why would this give it better bonding?


"DSK" wrote in message
...


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