Moving Chain plates?

[hegreen]

I have a problem with a leaking, thru the deck, chain plate. The deck is cored so my plan is to move all of them outboard. Should I even consider this if the hull is also cored?
BTW the boat in question is an older US Yacht 33 (which maybe a solid fiberglass hull all the way to the rub rail). I'm clueless on how to discover the hull design criteria.
I've read the ideas about materials to consider (I'm leaning toward titanium thru bolted thru the old hull imbedded chain plates.
Any cautionary tales to share?
Thanks folks for sharing all your wisdom. Your willingness to share is invaluable!

[coopec43]

Here is the basic specification if you haven't already seen them

https://sailboatdata.com/sailboat/us-33

I would consider the chain plates to be one of the more stressed parts of the yacht and if you don't know what you are doing I suggest you leave them well alone.

Why can't you fix the deck leaks? Apparently it is a common problem. Have you checked what other people have done? (There are a lot of articles on the subject)


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[tkeithlu]

Coopec speaks with wisdom, even if you do know what you are doing. Think of the mast, shrouds, chainplates, and a band of fiberglass extending down to the keel and joining up to the bottom of the mast as a stressed closed system. It likely has a bulkhead in it for added stiffness. Mess with it at your peril. The goal is to stop the leaks. Good luck with it.

[Searles]

Moving chainPlates on an inboard rig to out board would require a full redesign of the mast ,not the least ,longer spreaders and all new longer standing rigging,as the current rig is inline all standing rigging comes to a single point i e the inboard chainplate through the deck bolted to the blkhd pt and stbd ,best to fix deck leaks and check for rot in the structure. ⛵️��

[gonesail]

replace the chainplates (if needed) and fix the leaks .. don't re-engineer them.

[hegreen]

Thanks folks. I hadn't thought of all of the ramifications of changing the angles of the shrouds and the resultant forces. Fixing the leak is the way to go. I'll be careful to check for core rot.

[Sailor 99]

Originally Posted by hegreen

I have a problem with a leaking, thru the deck, chain plate. The deck is cored so my plan is to move all of them outboard. Should I even consider this if the hull is also cored?
BTW the boat in question is an older US Yacht 33 (which maybe a solid fiberglass hull all the way to the rub rail). I'm clueless on how to discover the hull design criteria.
I've read the ideas about materials to consider (I'm leaning toward titanium thru bolted thru the old hull imbedded chain plates.
Any cautionary tales to share?
Thanks folks for sharing all your wisdom. Your willingness to share is invaluable!

I am pretty handy and I will tackle almost anything. Put 6 layers of glass on a 50 ft yacht once. I am a do it yourselfer all the way



Moving chain plates is not a do it yourself job.



Fix the leaks. That is a 1 or 2 day job. Chain plates is way more and you will never trust them fully. No one will buy the boat from you afterwards.

[TeddyDiver]

Rebuilt them but get rid of metal through deck and do composite chain plates. A couple of pictures how to.. Sorry about the second picture orientation,

[Mike OReilly]

A previous owner of my did did what you are suggesting. The standard Rafiki-37 has inboard chainplates. Mine have been moved out, and bolted onto the outer hull.

I don't know what re-engineering was required to do this task. All I can say is, the boat is fine, and I absolutely love having my chainplates fully visible and easily accessible.

[CarlF]

I would not assume there's any core rot here as the builder likely sealed it well at the chainplates. Be careful as you check that you don't introduce a future core leak while checking.

I assume you've checked the chain plate attachment below decks for any sign of rot or bolts pulling out?

At deck level, it is important is to check if there's any sign of crevice corrosion in the chainplates where the stainless was oxygen starved as it went through the deck. It's best to remove them for this check but depending on deck thickness you can sometimes see well enough. If there's any question, replace the chainplates (and depending on age this might be worth doing anyways).

You could certainly try some new tech solution like titanium but the current one sure has given good service for a long time. I'd just replace with the same.

As for the leak that got you into this, I agree with the "use butyl" crowd. The leaks are caused by the caulk not sticking to the stainless chainplate after expansion and contraction has flexed it a few million times. The caulk always sticks fine to the fiberglass deck. As Butyl never really drys, it stays flexible and sticky for 40 years -- so it will move with the stainless instead of separating. Caulks like 4200 will stick for a while but eventually harden and separate. In any case, clean the chainplate well with acetone or other solvent so that there are no contaminants to interfere with adhesion.

But to make Buyl work it has to be held in place by a plate round the chainplate like in the picture. On some boats these get discarded along the way since you don't need it as much with an adhesive caulk like 4200. Pack the butyl in and screw down the plate to compress it. The best butyl tape for boats is from MaineSail https://shop.marinehowto.com/products/bed-it-tape

[Cheechako]

You can move them out, but maybe just repair the situation where they are.

If the deck is cored around the chain plates then hog some out from the inside and build up around them with solid glass work If they are attached to bulkheads etc you only need enough to seal it up well.