Fixing a leaky chainplate.

Chainplates which pass through the deck are very difficult to keep watertight and, being well forward, have a tendency to leak a lot. Most forms of seal work for only a short period as the working of the chainplate tends to open up whatever form of seal is used.

There are, however, a couple of tricks to making your deck seal last longer and/or work better.

If you are using a flexable sealant, like a silicone, do not tighten the seal plate initially. Push it down into the silicone gently, and then wait for the silicone to begin to harden. After it is cured about half way, take a few turns on the fasteners, bringing the seal plate about half way down. Wait for the next day, and then, when the sealant is fully cured, tighten the rest of the way.

This forms sort of an “O” ring which typically works better than the conventional approach, which is to tighten everything down while the seal is still wet.

An even better system is to make a gasket from wetsuit material – neoprene. Make the cut out for the chainplate a little undersize, so the neoprene has to stretch around the chainplate itself. Be sure to do this from one piece – which means the turnbuckle will have to be removed to put the neoprene over the chainplate. The neoprene will form a long-lasting and flexible seal around the chainplate itself, and around the fasteners from the seal plate.

Both of these approaches work well for other fittings as well.