Silicone

backcreeksailor · #1 (**permalink**) 04-21-2009

After reading through lots of posts here, I've gotten the message that in almost every case:

Boat + Silicone = BAD

So if silicone contaminates fiberglass so that nothing else will adhere to it; doesn't do anything useful for leaky windows; and should never be used to re-bed hardware...

Does "marine grade" silicone have ANY useful purpose? And if not, why do they continue to sell it in every boat supply store on earth?

donradclife · #2 (**permalink**) 04-21-2009

Silicone causes marine painters fits, but if you are not planning on awlgriping anytime soon, it is probably the best compound for bedding windows and hardware which you want to be able to remove. It works better when thicker, allowing for some expansion and movement, so countersink the holes when you are mounting hardware, and don't squeeze it all out when you are bedding windows.

The best silicones I have used are the 'neutral cure' ones, but the US doesn't seem to have heard of them.

AllThumbs · #3 (**permalink**) 04-21-2009

Quote:

Originally Posted by backcreeksailor

Does "marine grade" silicone have ANY useful purpose? And if not, why do they continue to sell it in every boat supply store on earth?

What they sell at a store has nothing to do with whether it is a good product for a specific purpose, and everything to do with whether people will buy it. If people want silicone, a store will have it available, lest the go elsewhere to buy it.

Eric

johnshasteen · #4 (**permalink**) 04-21-2009

Quote:

Originally Posted by backcreeksailor

Boat + Silicone = BAD?

Silicone might be okay in the northern climes, but down on the Gulf Coast where boats are in the water year, even the best marine silicone is worthless. In the brutal summer sun and humidity it turns black, and looses it's adhesive qualities - you can pull it off by hand. Use either 3M or BoatLife caulking.

jarcher · #5 (**permalink**) 04-21-2009

What about those so called "hybred" products that are part silicon, part something else?

AllThumbs · #6 (**permalink**) 04-21-2009

I think "boatlife" is a hybred. It's supposed to be pretty good for bedding plastic hardware, such as acrylic or polycarbonate portlights.

Bene505 · #7 (**permalink**) 04-21-2009

Quote:

Originally Posted by AllThumbs

I think "boatlife" is a hybred. It's supposed to be pretty good for bedding plastic hardware, such as acrylic or polycarbonate portlights.

Can I use it for my leaky hatches? I really don't want to spend $500 getting them re-done this year. I'd rather smear something around the metal to polycarbonite (?) junction (inside and out maybe) and forget it -- even if it means doing it agian next year. Boat is in southern New England. Lewmar hatches.

sailingdog · #8 (**permalink**) 04-21-2009

I wouldn't use silicone for this... given that most "quick repairs with silicone" look like crap and work about as well.

Quote:

Originally Posted by Bene505

Can I use it for my leaky hatches? I really don't want to spend $500 getting them re-done this year. I'd rather smear something around the metal to polycarbonite (?) junction (inside and out maybe) and forget it -- even if it means doing it agian next year. Boat is in southern New England. Lewmar hatches.

AllThumbs · #9 (**permalink**) 04-21-2009

Quote:

Originally Posted by sailingdog

I wouldn't use silicone for this... given that most "quick repairs with silicone" look like crap and work about as well.

SD, I think he is asking about using BoatLife for this, not silicone...

jarcher · #10 (**permalink**) 04-21-2009

Quote:

Originally Posted by AllThumbs

I think "boatlife" is a hybred. It's supposed to be pretty good for bedding plastic hardware, such as acrylic or polycarbonate portlights.

Yes, but if a hybred has silicon in it, why is it safer to use than silicon?