A cure for leaking chainplates

[joe28532]

After having to replace 4 out of 6 chainplate knees due to rot from water intrusion, I wanted to make sure I never had to go through that again. My chainplates were out because I was replacing them in these pictures. You don't have to remove yours to do this. Here is what I did;

I laminated 10 layers of 1708 biaxial mat into a block.

After that cured I traced the chainplate cover plates onto the block, cut them out with a jigsaw and used a drill bit to cut out the slot the chainplate goes through.

I then made sure they would actually fit over the chainplates.

The new block was then set in place over the chainplate on deck and its location was traced with a pencil. The deck was then sanded to bare fiberglass where the block would be placed. The block was positioned over the chainplate using thickened epoxy. The squeeze out was used to create a fillet. After everything was cured it was painted.

The cover plates were installed using butyl tape.

This raises the hole in the deck that the chainplate passes through and doesn't allow water to pass over an opening. No more leaks!!!

 

[Johnb]

G10 epoxy sheet is also a very useful material for this kind of work. I used a bunch installing new portlights.

 

[Stu Jackson]

Superb job. I used buytl tape the very same way, didn't do the blocks, superb idea! Thanks for sharing.

 

[chichiflys]

G10 epoxy sheet is also a very useful material for this kind of work. I used a bunch installing new portlights.

What thickness did you use?

 

[DianaOfBurlington]

I like this very much. I've been doing this or recommending it for about 15 years since Dave Cherubini insisted we do it 12 years ago with all major deck hardware. On my boat I have these plates ('bolsters' as DRC calls them) under the inner forestay tack plate and of course under all the stanchion bases (to make them level with the inside of the toerail, through which they are all bolted). I also sculpt them into the curves of the deck to accommodate Dorade boxes and other fixtures; I even made a winch base in the same way to fit one halyard winch on the aft end of the cabintop. Most people think these places were molded into the deck mold!

As for material, you can make them up (very time-consuming) or just use what you have or can get. I have used wood in the past but would not if you can do better. McMaster-Carr sell a 12" square piece of machine-rolled 1/4" straight fiberglass sheet for like 12 bucks. Cut it with any cheap carbide jigsaw blade from Harbor Freight. It is also excellent for backing plates under the deck. You can use G-10 or electrically-nonconductive fiberglass board (what I call 'redboard') as well; but they're tougher on cutting tools. StarBoard is completely unacceptable since nothing bonds to it, which is exactly the opposite of what you want here.

DO NOT seal metal chainplates in fiberglass with silicone, which will provide at best a temporary seal and will lead you to believe it's truly out of mind till the deck core below rots out. Butyl tape is another major cause of leaks later. Your bolsters should be bonded permanently to the deck (hardware removed) with epoxy or fiberglass resin, appropriately thickened with filler - anything else will be just another seam you have to worry about keeping sealed. Sand both surfaces very well, to white dust, with 80 grit, then wipe away with acetone. Using your fingertip as a radius, provide a fillet of epoxy around the perimeter to smooth the transition from the sides of your plate to the deck. If you use epoxy, you can paint with Brightside or some other nice paint. If you use polyester, it can be finished with gelcoat. For finishing you have two options: paint the edges (your fillet) of the bolsters with the nonskid paint/color, which sort of 'hides' them, or strike off the whole radius (your fingertip's width) as white and mask the nonskid around them like they're important. I've done both according to how each application looks best.

The SS chainplates can be caulked with LifeSeal; but remember that using LifeSeal precludes ever taping, painting or repairing with epoxy or fiberglass in the immediate area, as it is a blend of polyurethane and silicone. The best choice (only thing I would use) is 5200 UV. This will last 15 years at the least.

 

[Jim Legere]

DO NOT seal metal chainplates in fiberglass with silicone, which will provide at best a temporary seal and will lead you to believe it's truly out of mind till the deck core below rots out. Butyl tape is another major cause of leaks later...The SS chainplates can be caulked with LifeSeal; but remember that using LifeSeal precludes ever taping, painting or repairing with epoxy or fiberglass in the immediate area, as it is a blend of polyurethane and silicone. The best choice (only thing I would use) is 5200 UV. This will last 15 years at the least.

I don't often disagree with JC II, but here I must split tacks with him. Yes, silicone used to seal chainplates will always fail quickly. And I have had, at best, 3 years with LifeCaulk. But I would never, ever use 3M 5200 on chainplates, which should be removed and visually inspected for cracks every 5 - 10 years in any case. Butyl tape, applied properly (see MainSail's website), will seal the chainplates 100% effectively. Note that, if the boatbuilder has done the job properly, there should be NO exposed core in the deck penetration for the chainplate. If the hole was just punched through the deck, the exposed core must be rebated back and the space between the upper and lower skins completely sealed with epoxy. Only then can the chainplate be installed, bedded in butyl. Sealing the core is a trivial job if you are already installing bolsters.

 

[RoyS]

I like your raised block idea. Well done. The solid block also provides a good base for the cover screw threads, one of the usual sources of leaks into the core. There is one other area that needs attention and I have no solution for. The shroud itself conducts great quantities of rain water down to the top of the chain plate. I discovered this last Winter when water penetrated my poorly sealed chain plates to the boat interior. At the time my boat was shrink wrapped completely. The shrink wrap was taped tightly to each of the shrouds. To the eye no water could get by these taped shroud penetrations of the wrap but it certainly did. Some device that will shed rain water conducted down the shroud away from the chainplate needs to be invented. Envision tiny umbrellas just above the shroud attachment point.

 

[DianaOfBurlington]

I would never, ever use 3M 5200 on chainplates, which should be removed and visually inspected for cracks every 5 - 10 years in any case.

5200 can be surprisingly easily removed using a heated utility-knife blade and denatured alcohol - its Achilles heel. I would never, ever, seal metal chainplates through cored deck with anything as temporary as butyl tape or silicone sealant.

I will grant these should be inspected at around 10 years, as which time removing and replacing the 5200 isn't a bad idea. Use 4200 (1/3 as strong; in this application it doesn't matter) if you like. Remember the originals were in our boats 25-yrs-plus before we (the industry) began to encounter such bad SS that the likelihood of crevice-crack corrosion became a true worry.