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Re: Leaking portlights
I use "Bed It" butyl tape. You'll have to remove the frames and panes to install it. As HUGOSALT notes above, the mating surfaces must be squeezed with fasteners. It seems the reason many use silicon or 5200 is the expedience of just gobbing it on from the outside without removing the fixtures, but those "solutions" are only temporary. And 5200 eventually turns to powder. Butyl seems to last a very very long time, and it's resilient enough to maintain a seal with flexing and thermal expansion. I've used it to seal small cracks in my hull-to-deck joint sealing (compressed by a rub rail), chainplate deck penetrations, and port lights -- all areas that undergo a lot of flexing -- without further leakage. I've pulled stainless hardware off that I bedded 10 years ago, and the butyl was still hanging on tenaciously.
Being fully aware of the drawbacks, I have used Dow 795 construction silicon in a few places where I could easily abrade it off later.
Last edited by patrickbryant; 11-12-2019 at 11:20 PM.