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Old 05-16-2013
DrB DrB is offline
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Backing plate FG hull - Another Bonding approach

So I have replaced all of my Thru-Hulls and doing the last three this w/e.

None of them were through bolted before the fix.

I did Maine Sails approach of a threaded rod into a backing plate that was then epoxied to the inside of the hull. This approached worked well for the engine intake, but when I did it for the cockpit drains, (1-1/2" Thu-Hulls) I had a hell of a time releasing the thru-hulls after the dry-fit/epoxy cure of the back plates to the hull. Even though I waxed the hell out the all thru-hull and and backing nut, ultimately they didn't release and I needed to cut the backing nut, wack the thru-hull, and then just got it to break using a huge cheater bar.

A guy in the yard, who worked built ships for the Navy and now has a business fixing commercial and pleasure boats, suggested not using filled epoxy, but a high strength bedding compound for the backing plate. He first suggested through bolting to the hull, but I don't want to do that. After I told him about the backing plate idea, which he had heard of, he suggested a high quality and strength adhesive, like 4200 or 5200 for the back plate to the hull.

So the $64,000 question: why the need for epoxy and can I use high-strength adhesive instead?
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Old 05-16-2013
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Re: Backing plate FG hull - Another Bonding approach

I had no problems doing it using a good coating of grease

While 5200 is strong it is not remotely close to epoxy in strength

I guess the question is how strong is 5200 when holding a disk with 9 square inches of surface are ,and would the metal be just as likely to stick if the realse coating did not work
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Last edited by tommays; 05-16-2013 at 07:23 PM.
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