wood backing sealant

[tmw]

As part of cleaning the cabin of my CP16, I removed the wood parts holding the hatch cover in place. When I put them back, do I need a sealant to fill the screw holes? It appears there may have been something there in the past that I was able to scrape off the fiberglass.

Thanks!

[crazycarl]

yes, or you'll experience leaking.

i've used life caulk, 4200, and currently using butyl rubber tape.

the tape has a much longer life, cleans up easier, and dis-assembly is not a problem.

what you most certainly DON'T want to use is 5200.

cc

[wes]

Here's my hard-won experience with butyl tape vs polyurethane sealants like 4200, based on complete restorations of my 19 and 27 including rebedding of every last piece of deck hardware and exterior teak trim.

Butyl is best suited for through-bolted metal-to-fiberglass joints where you can apply the necessary strong tightening pressure without damaging anything. This includes lifeline stanchions, swim ladders, chain plates, motor mounts etc. A lot of force and repeated cycles of waiting and retightening are needed, but you end up with a joint that can flex under load without breaking the seal.

Polyurethane sealant (I like 4200) is better for screwed-on things like teak trim, where you can't apply great tightening force without breaking something, and when the surface is irregular and the ability of the sealant to fill gaps is helpful.

When I say "hard-won," I mean I used butyl on all my hatch slider trim on the 27 and ended up removing it and replacing with the 4200.

Wes

[tmw]

Thank you for the guidance.  I'll look for some 4000, as connecting the wood to the fiberglass isn't strong enough to justify butyl tape.

A search also brough up Loctite PL Sealants.  A Loctite Representative at Home Depot said The PL Marine fast Cure Adhesive sealant is very similar to the 3M 4200.

Someone reports that Practical Sailor (March 2015) says that they've been using Loctite PL Door and Window Sealant (S40) as a low cost alternative to 3M polyurethanes for a decade.

Does anyone have experience with these (Loctite PL Door & Window or Marine fast cure sealant)?

3M states  5200 has a tensile strength of 700 PSI, while 4000 has a tensile strength of 500 psi. 
Loctite states Marine grade has a tensile strength of 325-375 psi, while the Door and Window has a tensile strength of 380-450 psi.

Based on that this information it seems like both the Loctite products would work well without the permanence problem of 5200.  Does that seem right, or anyone else have experience with these?

Thank you again.

[Duckie]

Yeah, I have been using Loctite urethane sealants for a long time.  It is my preferred sealant right now.  I used it for the exact purpose that you are contemplating last winter when I refinished all the bright work on my 16.  It can be really messy to work with, but it cleans up with water.  If you go with it, I recommend that you not screw down tight your fasteners for a few days.  Let it set up a bit before you squeeze it all out.  Please don't use a sealant that has an adhesive effect.  Even if you don't have to worry about it, the next guy will curse you for it. 

Al

[Duckie]

OOPS.  I just checked and though I have used the Loctite product in the past, I am currently using DAP 230  waterproof sealant.  I have used this product in the past also and never had a problem with it.  In fact I just disassembled a through bolt on my weekender mast and found that the old DAP product was doing its job  better than I would have liked.  Meaning that the bolt was more difficult to remove than I would have liked.  I have used the DAP product on all kinds of outdoor applications, and have never known it to fail. 

Al

[Craig]

I would not worry too much about tensile strength unless you are using the sealant as an adhesive(which is actually what 5200 is). Above all, avoid silicone "sealants" like the plague! The seal will almost always fail and subsequent sealers will not adhere there.