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Old 20-02-2021, 05:34   #16
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Re: How to fix these buried chainplates?

I would not hesitate for a moment to open them up. I would likely open one up and deal with whats there and let that be a guide for the second,perhaps a guide on how to deal with them all.
If you sit for a few moments and think of what conditions you have been in. Think of the worst conditions you have been in, Think of what will be happening to those chainplates in bad conditions.....and what will happen if they fail.
It's not that hard to come to grips with the obvious now is it.

This is for the OP, I do not care to argue or deal with the trolls
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Old 20-02-2021, 06:32   #17
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Re: How to fix these buried chainplates?

The 40 is a great boat. When designed, Pacific Seacraft really pushed Bill Crealock to make a beamier boat than his other designs. I understand they met halfway. It is the only one with inboard chainplates so it was possible to have a tighter sheeting angle. It will do you well. You could probably contact Pacific Seacraft in North Carolina for information on the boat. I believe when they bought the assests of PS they have all the records also. They may be willing to share with you the best way to approach what you want to do. Again, great boat, I sailed on a couple of them
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Old 20-02-2021, 07:35   #18
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Re: How to fix these buried chainplates?

Stainless steel corrodes in the absence of oxygen. I bet there is significant crevice corrosion on those plates. Don't trust them.

Drilling a hole will tell you nothing !

The photos below show an x-ray of a single pin size pit on a stainless shaft. the void under that pit is hundreds of times larger. The photo of the broken shaft shows that the inside looked like a Cadbury Crunchy bar.

(Retired Certified Marine Corrosion Analyst)
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Old 20-02-2021, 07:44   #19
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Re: How to fix these buried chainplates?

Quote:
Originally Posted by coopec43 View Post
Why do you say they need work? What is wrong with them?

I definitely would stop water getting past the bolts but has that caused any problems?

Are the chain-plates stainless steel? If so I'd drill through the fiberglass with (say) a 10mm drill in a couple of different locations to inspect the state of the metal. If the metal looks OK maybe I'd pump some polyester (or epoxy) to fill any voids around the tangs.

If they were mild steel and rusted you'd have to cut them out and re-fiberglass in a new set.




This is terrible advice!!

When stainless is encapsulated itís unable to interact with oxygen. Once itís gotten wet and starts bleeding rust thereís very high probability that the chain plates are done or near done.

Pumping in a brittle substance like neat resin will only exacerbate the problem. Itíll serve to further block oxygen as well as encapsulate more saltwater in with the stainless.
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Old 20-02-2021, 08:03   #20
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Re: How to fix these buried chainplates?

Ummmm. It's really hard to tell. Be very analytical with your decision.

With Imagine, it all started with a collision at the start line of a race. A bent backstay was the only visible evidence. That chainplate was toast, but it was not discovered until we raced the Columbus Day Regatta on Biscayne Bay.

https://photos.app.goo.gl/UixFmDkv5R9sePjH9

--and--

https://photos.app.goo.gl/X39jmxM7MJhBXBNn6

Michael
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Old 20-02-2021, 08:20   #21
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Re: How to fix these buried chainplates?

I had a similar issue and went with external chain plates over the old ones ... cleaned up sealed the old ones and mounted new highly polished ss ones outside, drilling through the old ones. Ö youíll go through a couple of bits, but much better than removing/ repairing.
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Old 20-02-2021, 08:32   #22
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Re: How to fix these buried chainplates?

I can't believe all the lame advice you're getting on this. Open your eyes and look at the corrosion. It doesn't matter if it the chain plates where made out of stainless, iron or swiss cheese. Remove the chain plates, replace them with new plates and re-bed them. Find a way to not encapsulate them.
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Old 20-02-2021, 08:35   #23
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Re: How to fix these buried chainplates?

If 304, and even probably 316ss they very likely have crevise corrosion from being wet and encapuslated. I would definitely recommend full inspection and once you're in that far, replacement, so you might as well dig in fully. Why on earth would a builder glass over (and poorly at that) chainplates that are bolted through the hull side? They should have just layed up thicker hull laminate in that area and simply thru-bolted them, sealing them at the deck penetration. That way they can't sit wet with no oxygen, and could easily be inspected or removed. Better yet, put them on the outside of the hull (2 more inches outboard won't make much of a difference in sheeting angle) and never have to worry about chainplate leaks inside the boat.

An oscillating multi-tool with a carbide blade will be a bit slower, but make a lot less of a mess and have better control compared to a grinder. Make a couple slits just through the overlaid laminate, cutting it in a grid pattern, then use a chisel to peel it from the original hull layup laminate.

They *can* be one one at a time with the mast standing, using a halyard to a nearby cleat to take the strain, but I wouldn't recommend it at anchor if it's rolly or there is a risk of storms. Pulling the mast would make it go a lot faster and easier - it's going to take at least a week of long work if you know what you're doing and have it all planned out and replacement chainplates ready to go in and don't have to wait long for resins to cure, easily 4x that if you're learning along they way.

Please be mindful that failure of a chainplate will likely result in the loss of your rig and possible injury, certainly an extreme inconvenience. If you're planning to DIY this, consider at least getting some professional consultation and review of your plan and construction.
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Old 20-02-2021, 08:48   #24
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Re: How to fix these buried chainplates?

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Originally Posted by WaldPinkler View Post
No external plates on the boat.



Looks like I'll be doing some cutting. I like the idea of them not being sealed in fibreglass.
Yeah, the bolt heads are external though. I would just cut the glass loose inside, grind smooth. Remove and remake some. If you want to do it one side at a time you can hold the mast up with halyards etc. I second trying a multi tool for cutting. There are mini trimsaws like skil saws though that may get most of the cut. 3-4" blade.

I would not glass over them this time. Why they ever enclosed them is a mystery to me.
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Old 20-02-2021, 08:53   #25
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Re: How to fix these buried chainplates?

I know this does not help, but I have not seen this much in such highly respected production builds?
If it were me, I'd find a way to be able to monitor, access and service the chain plates at all times...
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Old 20-02-2021, 08:58   #26
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Re: How to fix these buried chainplates?

Maybe the photo from the inside of the boat gets people off course here. The problem is leakage. Unscrew the bolts one or two for each shroud, at a time, tap them out and re-bed them with Sikaflex and tighten them back in. Continue until all the bolts that leaked are sealed. You can leave the rig up, maybe just ease the bottle screws for the shrouds. The chainplates molded into the hull must certainly be S/S, otherwise you'd most probably have had a lot of rust in the inside. If they were mild steel and rusted they would most probably be quite swollen and you would see it. Do drill a little and see what it looks like.
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Old 20-02-2021, 09:01   #27
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Re: How to fix these buried chainplates?

Quote:
Originally Posted by Hermia II View Post
Maybe the photo from the inside of the boat gets people off course here. The problem is leakage. Unscrew the bolts one or two for each shroud, at a time, tap them out and re-bed them with Sikaflex and tighten them back in. Continue until all the bolts that leaked are sealed. You can leave the rig up, maybe just ease the bottle screws for the shrouds. The chainplates molded into the hull must certainly be S/S, otherwise you'd most probably have had a lot of rust in the inside. If they were mild steel and rusted they would most probably be quite swollen and you would see it. Do drill a little and see what it looks like.
And how does that determine if there is crevice corrosion in the plates (likely in the extreme).
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Old 20-02-2021, 09:12   #28
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Re: How to fix these buried chainplates?

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And how does that determine if there is crevice corrosion in the plates (likely in the extreme).
Please note thet I'm discussing the backing plates on the inside of the hull, not the chainplates. It would be most unlikely on the surface of a sheet of rolled steel. If it would have been a machined part with tight inside 90į angles for example and loaded, there could be a cause for concern. This is a very different loading situation.
It would be easy to take an angle grinder and shave off the GRP at the bottom of a chainplate just to see the metal. If it looks half way decent I would argue that removing them and replacing them is a lot of wasted time and money.
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Old 20-02-2021, 09:14   #29
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Re: How to fix these buried chainplates?

Nice looking boat, whatever. Am just a bit green... Good luck with the repair, whatever you do. If it was me i would definitely be talking to the maker & getting all the input I could from them before making any dramatic decisions. Also a surveyor experienced with those boats. You have external boltheads anyway so the idea of external chainplates on that boat (if necessary) would not put me off.
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Old 20-02-2021, 09:14   #30
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Re: How to fix these buried chainplates?

Quote:
Originally Posted by Hermia II View Post
Please note thet I'm discussing the backing plates on the inside of the hull, not the chainplates. It would be most unlikely on the surface of a sheet of rolled steel. If it would have been a machined part with tight inside 90į angles for example and loaded, there could be a cause for concern. This is a very different loading situation.
It would be easy to take an angle grinder and shave off the GRP at the bottom of a chainplate just to see the metal. If it looks half way decent I would argue that removing them and replacing them is a lot of wasted time and money.
So I'm guessing you know nothing of filiform corrosion in stainless steel.
i.e. that one piece of corroded ss in contact with another (and within itself) sets up a galvanic cell and spreads the corrosion.
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