San Juan 21 Class Association

I've been reading on some of the other sailing forums about the desirability of replacing chainplates. Some claim that the stainless steel is subject to corrosion and cracking that is difficult to see with the naked eye, and that after 8-10 years, it's wise to replace them. I know that mine are embedded in the fiberglass layup of the hull, and would be difficult to get out. Yet this area where the metal is concealed and where it comes through the gelcoat is where the cracking is most likely to occur.

Has anyone heard of an SJ21 chainplate breaking? Has anyone replaced a chainplate?

Thx in advance for your thoughts... Like there aren't enough other things to worry about in these old boats...

Roamer #162

I've removed mine, but it is the one piece I didn't replace. I think on big boats it is more of an issue where the pressures are greater, but others may correct me. I think the bigger issue is the high potential for water to get into the deck core in the joint. I pulled mine, drilled out as much wood as I could reach with the bent nail technique, then filled with thickened epoxy. I strongly recommend you do all hardware this way regardless of any previous owner's promises of having done it. Ask me how I know...

I was thinking of replacing mine as well. I have not located the chain plate yet but have heard as well that it is important to do. I also have heard it from other forums so it may still be a big boat issue like Kuriti said. Kuriti- You said you didn't replace. Did you just inspect it and it was fine so you put it back and the main concern was water intrusion? Was there any sign of water intrusion before you went in or was it more preventative care?

For any wood cored deck, water intrusion is the biggest enemy because it can happen silently and have terrible consequences. Therefore, I strongly recommend drilling and filling all through deck fittings (and transom). It's tedious, but nothing compared to re-coring your deck. I removed my chain plate and inspected as part of my refit, but just used the old ones. That decision was based on the scientific method of guesstimating that they looked beefy enough not to worry about them. If anyone has knowledge of them failing, please share. I'm guessing the rivets would pull through the mast before the stainless chain plate fails. Certainly won't hurt to replace though.

Yesterday I was rebedding one of my hand rails and I noticed that one of the rivets on the plate that goes over the chain plate had snapped off and that plate had lifted off the deck a little. I guess that will be my next repair. So I drill out the rivets and replace them with through-the-deck bolts?

My recommendation stays the same. Pull the entire chain plate, chip out the wood between the inside roof layer of fiberglass and the deck layer of fiberglass as far as you can using a bent finishing nail in a drill. I snip the heads off. Then duct tape the resulting hole from below and fill with thickened epoxy. Once dry, re-cut the hole by drilling several holes in a line and Dremel/saw/zip-saw the appropriate shape for the chain plate to fit back through. To your question, I used small stainless screws to hold the plates on, but they were biting into epoxy, not wood core. If the rivet came out, your core is getting water in it every time it rains. Don't be afraid, you can't break anything that can't be fixed.

I had a chainplate break a few weeks back during a race, fortunately no major damage (had to replace the mast step, which was pulled out and of course the chainplates). I suspect that the use in salt water by the previous owner caused the corrosion, the crack and the ultimate failure. It might have happened sooner, if I had not replaced the wooden bulkheads with 4" wide 1/4" thick aluminum plates. I would think this kind of failure is rare, though I would suggest a periodic (yearly) inspection, since having a mast with the sails in the water is not a fun experience. The help of the mark boat was greatly appreciated.
Guy Goettsch
Juannabe Sail#1721

Guy;

Where exactly did the chain plate fail? That's where I want to check mine. I don't understand what the bulkhead would have do do with it. The chain plate attaches to it below the deck with six or seven bolts. My mast had what we RC pilots call a "rough landing" from about five feet that bent my chain plates back about 30 degrees. My reaction was to straighten them back with a pair of pliers. Now I'm thinking I just better replace them.

Condre'
Bucket List #2517

Condre,
The chainplate failed belowdecks just above the top bolthole. Originally I had the wooden bulkheads and, since I have my shrouds fairly tight ( 15 - 20 on the inners and 10- 15 on the outers) there probably was movement of the chainplates (I was never able to seal it well). The fact that it had been sailed in saltwater probably contributed to the corrosion also.
In yesterdays clubrace I overheard on the radio that another San Juan 21 had to retire due to a chainplate failure, though I don't think the mast went overboard.
If you bent yours back into alignment, there clearly has been some stress. I would recommend that you replace yours (I got mine from Stephen Jensen for $ 25 each), a small amount for peace of mind.
Hope this helps.
Guy

That's hard to figure. I'd think any movement would be happening at that little plate that that the chain plate goes through on the deck. Yes, I worry about my bent chain plates. But now I'm also worrying about what kind of damage the shrouds and turnbuckles may have sustained.