Silicon bubbling

[geoffschultz]

We stored BlueJacket in Panama last year and will store her there again this year. It rains a LOT down here. When we returned we noted water damage on the wood next to the mast in the salon. After doing some detective work, I noted that the silicon around the stainless mast ring had failed. I cleaned all of it out and reapplied silicon. That was in February. Just yesterday was I looking at it and noted that there are bubbles appearing under the silicon and I can see that it will fail again. The attached photo shows this.

The questions are:

• What's causing this?
• What do I do to keep this from re-occurring?
• What product should I be using?

-- Geoff

 

[woodster]

i would take it loose and clean all that (silicone) sealant off and re bed it with butyl...maine sail has some of the best ....walla problem solved

 

[geoffschultz]

Thanks for the suggestion, but I'm in Panama and butyl isn't exactly common around here. I had a roll of butyl from MaineSail that I just threw out because it wouldn't release from the release-paper.

Right now I'm leaning towards a polyurethane product, such as 4200.

-- Geoff

 

[arf145]

I'd go with anything other than silicone. But in order to get a bond with your 4200 you'll need to clean the obvious silicone off well and then use physical means like fine sandpaper to get the silicone residue off.

 

[centerline]

Thanks for the suggestion, but I'm in Panama and butyl isn't exactly common around here. I had a roll of butyl from MaineSail that I just threw out because it wouldn't release from the release-paper.

Right now I'm leaning towards a polyurethane product, such as 4200.

-- Geoff

the 4200 is good stuff, but you will probably have the same results with it... but as its opaque, and not clear, you wont see it...

the problem i think you are having is.. there is moisture trapped under the fitting. when you applied the silicone, it sealed the "vent" and as the sun heats the fitting the increased pressure as the moisture tries to escape is causing the silicone to be pushed away from what its supposed to seal..

you will need to remove the silicone and let it dry out for a few days... acetone or lacquer thinner is a good carrier to get in and dilute the water, and allow it to be carried out quicker as the solvent dries. but time is still needed unless you can remove the fitting and rebed it properly.

make every effort to remove every trace of old silicone, as nothing likes to stick to cured silicone.... not even more silicone. ether (common starting fluid) is the best for dissolving the residue of silicone, and a light scrub of steel wool or a scotchbright pad helps also...

 

[geoffschultz]

Thanks for all of the good suggestions. Dis-assembly would be a major job, but it may come down to that as finding several dry days to let dry it out may not be feasible.

-- Geoff

 

[geoffschultz]

Thanks to everyone for your suggestions. Because I'm in Panama and have *very* limited access to anything other than the normal marine adhesives, I used 4200 Quick Set. Let me tell you, when it's upper 80s, the term "quick set" is an understatement. By the time that I had worked my way around the mast with the caulking gun, it had already begun to set up. I was able to tool it, but had problems when removing the masking tape and the edges aren't the prettiest.

I've also pretty much determined what the issue is. The mast ring is stainless which is bolted to an aluminum bottom plate and there's nothing separating the two. As a result you have electrolysis. I spent a hour or two with dental tools carefully cleaning out all any corrosion that I could get to and get down to bare metal. I then used a stainless steel brush to clean it all up and then wiped down with acetone before applying the 4200.

I think that the best solution would be to place some kind of plastic barrier between the two. Alternately perhaps I could apply some kind of epoxy paint on the 2 surfaces. However, I'm trying to get the boat ready to store for hurricane season and just don't have time to work on this now. But I'm open to suggestions!

-- Geoff