sealing anchor chain pipe

[rmeador]

The hole for the anchor chain pipe on my boat goes straight through the deck with no seal on the inside, thus exposing the deck core. My surveyor found very little moisture in it (thankfully) and recommended I dig out some of the core and fill with thickened epoxy to seal it. I've already got a tube of 3M 5200, would that work for this task or do I really need the epoxy? If I need the epoxy, can someone recommend specific brands, hardeners, and thickening agents? I have never done this before, so I don't know how to tell what is a good epoxy for this job. I also have a roll of butyl tape I plan on using to rebed the thing that the companionway hatch cover slides into (what's that called? I know it has a name), but I don't know if that would be useful for the chain pipe.

[mitiempo]

Any brand of epoxy will work. I use West but Mas, System 3 and others are good also. Thicken it with colloidal silica, usually available where the epoxy is sold. The epoxy is better than 5200 and will seal the top and bottom skin together as one. You should remove the core about 3/8" all around as well as overdrill the holes for the bolts or screws. There are various ways to do this but for a larhe hole I use a router bit that carves it out nicely. Butyl would be a good choice for bedding the chain pipe as well as the sea hood over the hatch. Here's a link to Mainesail's how to attach hardware.
Sealing Deck Penetrations to Prevent Core Rot Photo Gallery by Compass Marine at pbase.com

[sailingdog]

Originally Posted by rmeador

The hole for the anchor chain pipe on my boat goes straight through the deck with no seal on the inside, thus exposing the deck core. My surveyor found very little moisture in it (thankfully) and recommended I dig out some of the core and fill with thickened epoxy to seal it. I've already got a tube of 3M 5200, would that work for this task or do I really need the epoxy?

You could do it with 5200, but it would work much better with epoxy. One good vendor is Progressive Epoxy Polymers in NH.

If I need the epoxy, can someone recommend specific brands, hardeners, and thickening agents? [/quote]

Just follow Maine-sail's directions, which mitiempo linked to.above, which can be summarized as:

• Route out the core material for about 1/4" or so.
• Then coat the wood core with unthickened epoxy
• Then fill gap between the fiberglass layers with thickened epoxy. Thicken the epoxy with colloidial silica or cabo-sil.

I have never done this before, so I don't know how to tell what is a good epoxy for this job. I also have a roll of butyl tape I plan on using to rebed the thing that the companionway hatch cover slides into (what's that called? I know it has a name), but I don't know if that would be useful for the chain pipe.

The housing the companionway hatch cover slides into is usually called a sea hood. You can bed the chain pipe with butyl tape as well. Butyl tape is a great sealant for anything that is through-bolted, above the waterline and not typically exposed to fuel—as butyl tape will degrade with exposure to fuel.