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Do I seal the foam or just cut and paste?


New Member
I have a 1980 Alcort Sunfish and just recently tried to install a second inspection port on the stern. I was back far enough to avoid the little cubby area, but not far enough to miss the styrofoam block. I don't think it's a huge deal, I really only need this port to help dry out the boat. Right now it's easier to dry her out than find and fix all the leaks.

My concern is with the styrofoam and the expanding foam. After I've cut away enough to I stall the port and for airflow, should I apply a sealant to the foam bits I've exposed? Will it even matter?

Lafayette Mike

Active Member
No need to "seal" the foam. Not sure how you'd do it anyhow.

And after you get the boat dried out "which can take a longggggg time", you really want to find and seal the leaks. You don't want to make the drying out an annual process! And if the boat is "dry", there is no need to "seal" the foam anyhow.

Mike (still drying out my 1972 boat)

Alan S. Glos

Active Member
I agree with Mike - no need to seal the edges of the foam you have cut through to install the port(s). If anything, the exposed foam will speed up the drying process a little. But do a simple leak test. Soap up the hull with a spray bottle of soapy water while blowing a little air into the hull through the deck drain hole. I use a small vacuum cleaner on blower mode to provide a little internal air pressure (don't use too much pressure or you can damage the hull.) You will find the leaks easily and can patch them with Marine Tex or thickened epoxy. Not a lot work.

Alan Glos
Cazenovia, NY

signal charlie

Well-Known Member
Staff member
No need to seal it, the foam is closed cell. You can pull out excess expanding foam except for what secures the white foam blocks.