Bedding Deck Mounted Chainplates

[Sailor_Grant]

Is Life Calk a good sealant to use for deck-mounted chainplates? The chainplates are bronze, with stainless steel thru-bolts with a mild steel backing plate. Please see the below diagram.

I do not want to use 5200 as it makes it incredibly difficult to remove the bolts (which is what I just dealt with), and I do not believe butyl will seal the entire hole through the hull.

It is crucial to prevent water ingress to preserve the integrity of the mild steel plate and prevent crevice corrosion.

[phorvati]

Originally Posted by Sailor_Grant

Is Life Calk a good sealant to use for deck-mounted chainplates? The chainplates are bronze, with stainless steel thru-bolts with a mild steel backing plate. Please see the below diagram.

I do not want to use 5200 as it makes it incredibly difficult to remove the bolts (which is what I just dealt with), and I do not believe butyl will seal the entire hole through the hull.

It is crucial to prevent water ingress to preserve the integrity of the mild steel plate and prevent crevice corrosion.

I did mine with lifecaulk and it cracked within 3 years. I am redoing them now with butyl. However my stemhead(headstay), and innerforestay i did in lifecaulk as well and it did not crack. Your picture is similar to my stemhead and inner forestay fittings.

[mike d.]

Butyl tape !!!!!!!!

[JoeRobertJr]

I read an article in BoatUS this morning about bedding compounds. The author favored polysulfides, like Life Caulk, so I think the answer to your question is Yes, that would be a suitable sealant for that application.

I just did mine with butyl. With the screw holes, it is important to tighten the fitting via the nut, not by turning the screw, as that shears the butyl that you wrapped around the base of the screw head.

[Benz]

Look at the caulk that people use below the waterline, and is recommended for that use. That will be the stuff that, used properly, keeps water out long term.

[Davidhoy]

Butyl tape is the best stuff for bedding any deck fittings. It never dries out or hardens, so it remains flexible and can handle the stresses and strains, and inevitable movement, of your chain-plates. It's the only stuff I use for deck fittings, never had a leak.

Rod Collins has an excellent website for marine know-how, and he has a section dedicated to butyl. He also sells the stuff.
https://marinehowto.com/bed-it-tape/

[Boston Blackie]

The KEY POINT Rod stresses is the need to countersink the surface o f the gelcoat under the deck fitting to create a thick triangular ring of butyl massively compressed against the bolt and the deck. Proper compacted butyl of large enough sealing thickness will never leak.