Neil, My boat yard uses Boat Life Life-Caulk for everything they want to waterproof--underwater or in the weather-- so I used it for my cutlass bearing and a teak mount for a through-hull transducer, and for mounting stanchions, etc.. Everything else is hard to work with or gives up after a decade, but this stuff never seems to change with time; I'm sold on it. Tom Jenkins M17 Scintilla On Nov 15, 2009, at 2:15 PM, ndorf@surfbest.net wrote:
Thanks to all who who responded.
Sounds like the jury is split.
Jerry recommends a polyurethane adhesive sealant and not silicone.
One vote was for polysulfide sealant (Boat-Life Life-Calk)
One vote for a polyurethane-silicone blend (Boat-Life Life-Seal).
I'm no chemist, but from what I can tell by researching these compounds, the first two would the best choices with the primary difference being that polyurethane is very permanent, while the polysulfide, while having similar seal and adhesive properties, is less so and with some work could be removed at a later date if further maintenance is required.
I think I will go with the polysulfide in case for some unforeseen reason I have to pull the step off again (gosh I sure hope not).
The Life-Seal is apparently the best for plastics such as port-lights, since polysulfide will etch and gradually destroy plastics while the polyurethane+silicone blend will not.
If I were building a brand new boat, I would probably use polyurethane adhesive sealer for the best longevity.
Thanks again.
Neil
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