On our 1983 PSC 37 rust stains ran down the hull from the chainplates. We cleaned the reachable portions of the chainplates and realized that the majority of the rust was coming from the shrouds and shroud fittings. We decided to inspect the chainplates more thoroughly because we were planning to take the boat offshore.
To remove the chainplates, we had to do the following:
1. Remove the teak battens in the salon. The teak battens extended behind the trim pieces on the forward and aft bulkheads, which required removing the teak trim end pieces. On our 37, we had the old style interior which did not include the bookcase and lockers--the battens extended the length of the settee. Removing the battens exposed the area where the chainplate bolts were. Our bolts were finished over with a few layers of woven roving/fiberglass, preventing our seeing them or accessing them.
2. We used a hole saw with the pilot bit removed to cut the roving away from around the nuts. The hole saw was large enough to remove the woven roving over the nut and leave a big enough hole that a socket could then be fitted down flush over the nut.
The nuts for the aft and center chainplates were relatively easy to get to using this method. The forward chainplate nuts were much more difficult. The starboard forward chainplate nuts were barely accessible through aft end of the sliding door cabinet in the head. Reaching the nuts was difficult, but possible.
The port side nuts were somewhat easier, being accessible through the hanging locker on the port side. This hanging locker had the carpeting lining the hull, so we had to peel back the carpeting first.
If you're lucky, you will have carriage bolts attached to these nuts. If you're not, you'll have some unlucky person standing outside to hold the bolt head while you unscrew the nut. We had ordinary round-head bolts in round holes in the chainplates. Fortunately, the bolts were tight with old caulking and held their position while we removed the nuts.
Putting the nuts back on required having someone on the outside with vise grips held flat against the hull, gripping the bolt head so that it wouldn't turn.
3. Once the nuts were off and the bolts forced out, we broke the chainplate free from the hull. Each was caulked firmly to the hull. Caution: don't try to chisel underneath the chainplate because you'll bend the chainplate.
We removed ours by using the rigging
- Loosen all six shrouds: port and starboard forward and aft lowers and the two uppers.
- Working on one _lower_ chainplate at a time, tighten the shroud on that chainplate until you get a couple of inches sideways bend in the mast (this means that shroud is very tight). The chainplates for the lowers should break away before you have to tighten their shrouds this much. If a chainplate won't break free and you've tightened as much as you dare, get a piece of wood--2x4 or 4x4 about 2 feet long--a very brave assistant to hold the wood almost flush with the side of the hull with the end of the wood against the very bottom of the chainplate, pushing up against the bottom of the chainplate. Use a sledgehammer and strike the wood with several (it may take as many as 8-10) taps to break the chainplate free from the caulking. You will know when it breaks free because the chainplate will move and the mast will snap upright. It's pretty obvious.
- Break all the lower shroud chainplates free the same way.
- Because the upper shroud has a longer chainplate and because it goes underneath the rub rail, it's harder to deal with. The same technique will work--be patient and fearless.
One last potential trick: if you can, worm a very thin wire between the chainplate and the hull and saw it back and forth to cut the caulking away as much as possible.
Once our chainplates were free, we inspected them and found them to be sound after 20 years. We did, however, have them cleaned and polished to a
high polish to help retard further oxidation.
Reinstallation uses the opposite steps, minus the sledgehammer, and is fairly straightforward. If you don't have carriage bolts, you will still need someone holding the vise grips flat against the hull, with the head of the bolt held by the sides of the vise grip jaws, not the end.
If you have square holes and carriage bolts, we envy you.
We did not get to the chore of removing and inspecting the forestay and backstay chainplates. Our assumption is that if you have the strength of Samson and the arms of a gorilla, and are familiar with maintaining a Jaguar XKE, you should have no problems.