Chainplate rebeading & covers

[SailorPaul]

So it's time to redo the sealant bedding the chainplates on our 41'. I'd like to put two considerations up for discussion. It would be nice to find someone with practical experience with these sealants -- instead of just the "mfg claims"?

1. There has been some discussion in PS, Dow tech support, and other places about better choices for the actual sealant. It took some tracking but here's what I've found. They are recommending these sealants for keeping a water-tight bond to the stainless are:

-- N.A, Premire Silaprene, a neoprene sealant with high adhesion to
stainless
(the fiberglass requirment is trivial for all of these)
Mfg by Royal Adhesives & Sealants (Uniroyal?)
prep is wipe surfaces with IPA (alchohol)
Toluene based solvent,
Steel 415 psi lap sheer
500% elongation
Permanantly resilient & excellent weatherability,
Outstanding resitance to water, fuel, oil, industrial chemicals, acids
and bases.
Comes in white, off-white grey, aluminum and black
No UV effects
Applied bead will SHRINK about 50%, so NO tooling is needed for most applications
Tack free in 15 - 45 minutes, initial set in 4 hours after which parts may be handled.
After 24 hours at room temp it is considered self holding.
Use of a 150 degree heat lamp for 1 hours will speed solvent evap and strength build-up.
Excellent early strenght, get's stronger with age.

-- Sikaflex 291 or 292 (elastic 700%) and (bond strength 200 psi),

-- Or Bostick 2100sps (elastic 400%) and (bond strength 175 psi)?

The other marine sealant choices apparently all have issues with stainless steel adhesion. Whoda' thought.

2. Chainplate covers. I don't like having to undo the shrouds in order to remove the chainplate covers and work effectively. Thinking about making two part units that are either:

A bar & U _ + |_| I could cut the existing covers with a Dremel cutting blade to get this result

or mfg two overlapping U shapes |_| + |_|

Any feedback or observations?

[Steve Kidson]

I would recommend Sika products as quality products for sealing in the marine environment.

I have found 291 to be excellent for all deck fittings, hatches and the like; I cannot see why it would not be suitable for your chainplates.

I have used 290 for teak decking, and have found it to be more than satisfactory as well.

Sika are probably not the cheapest sealants, but would rank right up there with the best.

Use the best you can, last thing you want is leaking through the decks or topsides. As fate would have it, your leak will be directly over your berth, settee, nav station or galley - the most inconvenient places.

Fair winds

Steve