This is not what a chainplate should look like!

2 Mar

Early on in this project I decided that I would try my best to do all of the work without professional assistance. There are a few reasons for this, including finances and bull-headedness but the primary benefit is that by forcing myself to learn every in and out of my boat I expect I’ll be prepared for whatever may go wrong in the future. Generally this has worked out well. Sometimes my progress is glacial but when I’m done I haven’t broken the bank and it’s hard to beat the satisfaction of repairing some part of the boat that I knew nothing about just a week or two before. Then there are the repairs that I maybe should have left to a professional. These are the jobs that seem straightforward on paper but never turn out quite so simple as described. The chainplates, for example.

The chainplate saga begins a few days into my new life as a boat owner. I was still in that giddy phase where my beautiful ‘new’ boat could do no wrong. Poking around turned up plenty for my to-do list but still I was in constant awe with what we might call the immense solidity of my overbuilt boat. Then I poked my hand up into the hull liner by the main bulkhead and was surprised by a light sprinkling of what felt like paint chips. I scratched a little more forcefully and down rained quarter-sized flakes of rust. I had finally found a flaw that even I couldn’t ignore – all the chainplates were made of plain old mild steel and after thirty-five years they were disintegrating.

After taking a day to vent my frustrations I got down to business. The first step was to figure out exactly what these rusted hunks of metal once were. This would seem easy but the chainplates on a Cape Dory are quite bizarre. Here’s what the aft one looks like.

Not very intuitive. Cape Dory owners sometimes call this ‘The Thing’
Here’s a less rusted one (not mine) after removal. It is inverted – installed in the boat the plate is butted against the underside of the deck while the rebar arms in the foreground are glassed into the transom.
That’s a piece of 3/8″ steel plate welded to three lengths of rebar and then glassed into the transom. The holes are for bolting a padeye on deck for the backstay attachment.
The port and starboard chainplates are no less strange. They consist of a length of steel about three inches wide by three feet long which has lengths of rebar welded to it. The steel plate sits under the deck acting as a backing plate for more padeyes while the rebar is glassed into the hull to spread the load.
 Here’s the best photo I could get, showing the plate from the underside. The hull is in the lower part of the photo and you can just make out one of the glassed-in lengths of rebar at about four o’clock. All this is up under a hull liner and quite difficult to get at.
Finally there is the reinforcement for the forestay. These are simpler, just a pair of oversized steel plates glassed into the forepeak. Mine had expanded so much from severe corrosion that the one on the port side had split open the fiberglass. Here they are partly exposed:

Obviously I was a bit dismayed by all this rust but I was full of energy so I got started right away. the first task was cutting out the rusty old plates. This ‘simple’ task served as my introduction to how infuriatingly awkward, uncomfortable and difficult working on a small boat can be. Just getting to the aft chainplate required crawling into the cockpit locker and then curling myself into the transom. To cut it out I had to reach up at an awkward angle with grinder in hand. It was hard to see to begin with and every time the grinder touched the hull the tiny space would fill with fiberglass dust and I wouldn’t be able to see anything. I was literally cutting by feel half the time. Plus the close quarters and the size of the grinder meant it was almost impossible to cut where I wanted to. It took several hours and a borrowed tool (a smaller pneumatic grinder) just to expose the rebar on the aft chainplate:

 The forepeak was equally awkward although at least the shape of the hull was a little better suited for cutting out the plates. Here’s how things looked up there:
 Once I had cut away the glass I removed the chainplates by hitting them with a hammer until they formed a pile in the bottom of the locker, like so:

 I looked like like a very itchy ghost by the time I had finished:

As for the port and starboard plates there wasn’t even access for a grinder without cutting out large sections of the hull liner. I did manage to get the forward plates completely removed but since my new chainplates will be external I decided in the end to just leave in the port and starboard plates and some portions of the aft plate. This saves me from chopping the boat up any more than I have to and I can’t see any detriment to leaving the old stuff in. Out of sight, out of mind.

With the boat more or less prepped for new chainplates I spent a week poring over books and internet forums trying to learn as much as I could about the construction of this critical component. I was feeling quite confident by the time I finally got started but this confidence was short lived.

This article was syndicated from Safe At Harbour But Meant For The Sea: DIY Sailing with Paul Calder


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