Sealing high-volume chainplate deck slot

[LifesBetterWhenYoureBeating]

New year, new chainplates, but first I need to figure out the best way to seal the deck slots through which they enter. I have a raised base on deck and the slots are about 2" wide by 1" high by 3" long before they get narrow enough for just the chainplate to squeeze through. Any suggestions on what to use to fill that 1"x2"x3" area?

[wyb2]

Assuming it narrows at the surface, where the chain plate exits? If so, why do you need to fill this area underneath? Just bed the chainplate with your favored product and let the rest breathe. If it leaks in the future you want to know about it, you don’t want 3” of vertical sealant trapping water out of sight.

[LifesBetterWhenYoureBeating]

Originally Posted by wyb2

Assuming it narrows at the surface, where the chain plate exits? If so, why do you need to fill this area underneath? Just bed the chainplate with your favored product and let the rest breathe. If it leaks in the future you want to know about it, you don’t want 3” of vertical sealant trapping water out of sight.

The surface is where it is much wider/longer than the chainplate. It's like that for almost 1" down from the deck before it gets narrow

[jordanbigel]

Originally Posted by LifesBetterWhenYoureBeating

The surface is where it is much wider/longer than the chainplate. It's like that for almost 1" down from the deck before it gets narrow

That does sound unusual. Some photos would be great (I am curious!)

[wrwakefield]

To avoid blocking oxygen from a large portion of a SS chainplate [thereby promoting crevice corrosion over time] I prefer sealing chainplate deck penetrations [on non-metal decks] with a cover plate- which is sealed with butyl tape.

Granted, there will still be a small margine of area on the SS chainplate that will be oxygen starved, but it is easily inspected by removing the cover plate.

And by leaving the deck penetration area unsealed, the metal is exposed to air full time, and will dry even if the deck plated leaked.

In case this is useful.

Cheers! Bill

PS: I always coat the portion of the chainplate below decks (as well as all bronze through hull fittngs and valves) with CorrosionX (since mine are hidden behind cabinetry.) They have been coated since 1999, and still zero corrosion as of last year. The corrosionX may not be why all 16 of our chainplates [ketch] are corrosion free, but at the very least it provides lasting secondary protection. The next best thing would be titanium chainplates...

[Calif.Ted]

Chainplate covers are often used with butyl as a sealant, some of the European boats have a larger raised dome cover.
https://rigrite.com/Hardware/Chainpl...ate_Covers.php

[LifesBetterWhenYoureBeating]

This is what it looks like

[wrwakefield]

As I suspected (See my post #5, above.)

You don't need to fill the slot in the deck with sealant. (Nor is that desirable per reasons given in my above post)

Clean up the deck and chainplate cover and only put sealant (high quality butyl tape works very well, and is removable) on the deck side of the cover plate. Screw it down to distribute sealant (but not too tight until it sets if using Sikaflex 291 or the like; tighten as much as you can if using butyl tape.)

In hopes this helps.

Cheers! Bill

PS: If the deck is cored, be sure to seal the core at the penetration with epoxy...

[Searles]

Make up a plug just larger than the intended chain plate ,add release agent ,mixup some epoxy with glass strands and fill ,when cured remove plug and fit chainplate using deck plate to seal ,use high grade sealant ,do not try and fill that gap with flexible sealant,bound to fail.⛵️⚓️

[wyb2]

Originally Posted by LifesBetterWhenYoureBeating

This is what it looks like

Looks like someone hogged it out with a router. Maybe the builder, but I suspect a previous owner.

So the distance from the top of the gel coat to the wood surface in that 1st photo is 1”? You could probably get away with just filling the whole void with sealant and screwing down the cover plate, basically a very standard chainplate rebed but just using a bunch of extra sealant. Downside is if you use some curing liquid, seems like it would be a bear to redo in the future. If you use butyl tape, it should be easy enough to pull it back out (if you ever have to redo it).

As someone said above, you could also fill the void with epoxy, then you won’t need to waste a ton of sealant and you will have better protection for the wood core. Instead of making a plug to mimic the chainplate, I’ve used the chainplate itself, wrapped once in painters tape, then again with the sticky side out. When you are done, the tape peels off easy enough from both surfaces and you have a slot that is exactly the right size.

Bonus points for drilling out the cover plate mounting holes with a larger bit, taping the bottom, filling with leftover epoxy from the main job, and redrilling for small (#8 or so) through bolts.

[LifesBetterWhenYoureBeating]

Originally Posted by wrwakefield

As I suspected (See my post #5, above.)

You don't need to fill the slot in the deck with sealant. (Nor is that desirable per reasons given in my above post)

Clean up the deck and chainplate cover and only put sealant (high quality butyl tape works very well, and is removable) on the deck side of the cover plate. Screw it down to distribute sealant (but not too tight until it sets if using Sikaflex 291 or the like; tighten as much as you can if using butyl tape.)

In hopes this helps.

Cheers! Bill

PS: If the deck is cored, be sure to seal the core at the penetration with epoxy...

That wouldn't seal the area between the cover plate slot and the chainplate sides though, right? What would be the best way to seal that?

[wyb2]

The cover plate should be installed before the sealant cures (or whenever with butyl), forcing it to squeeze out the edges and seal against the chainplate. 1000 words...

[LifesBetterWhenYoureBeating]

Originally Posted by wyb2

The cover plate should be installed before the sealant cures (or whenever with butyl), forcing it to squeeze out the edges and seal against the chainplate. 1000 words...

That's how I did one but it's not how @wrwakefield described it

[LifesBetterWhenYoureBeating]

Originally Posted by wyb2

The cover plate should be installed before the sealant cures (or whenever with butyl), forcing it to squeeze out the edges and seal against the chainplate. 1000 words...

I've done that on one of the chainplates with 3M 4000UV as it's supposed to be "extremely flexible". Is there anything more suitable? On the owners group someone said they packed with nylon line as well

[wyb2]

Originally Posted by LifesBetterWhenYoureBeating

I've done that on one of the chainplates with 3M 4000UV as it's supposed to be "extremely flexible". Is there anything more suitable? On the owners group someone said they packed with nylon line as well

I think there might just be a little confusion on how large a void exists on the top side (I would not have guessed it was 1” deep just looking at the picture) and what we are calling the “slot”.

4000 UV I think is fairly popular for this kind of job. I prefer butyl tape (Bed-it brand is marketed for boats and not much more $ than the cheap stuff on Amazon of unknown origin), but some people prefer the liquid sealants. Either will work.

Edit: Nylon rope? Don’t do that. Don’t reinvent the wheel to save $4 on sealant.