inspecting chainplates on 1987 P31-2

[Mike Butler]

Hello there,

This spring my "to do' list includes inspecting the chainplates. Something I've never done before. There is no  corrosion above deck. Below deck there is a bit of rust/corrosion on one bolt on the starboard side, while the port side has no evidence of corrosion.Can anyone recommend any youtube videos or articles about the best approach?

Has anyone in the group inspected their chainplates and found corrosion severe enough to warrant replacement?

And if I have gone to all the trouble of removing the chainplates so I can check the section that is between the deck and cabin liner is it better to just go ahead and have new chainplates fabricated?

Thanks very much for any guidance and tips.

Mike Butler

"Vela"

1987 P31-2

Weymouth, MA

[Guy Johnson]

I pulled the chainplates on Puffin, polished, inspected and reinstalled. 

Before reinstalling I de-cored the surrounding deck and made new deck plates from 1/4" fiberglass. 

If you can see any indications of crevice corrosion (thin lines of corrosion on the surface or deep pits) I would have new chainplates made. 

Guy

Puffin 10M #6

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From: pearso...@googlegroups.com <pearso...@googlegroups.com> on behalf of Mike Butler <mikebut...@gmail.com>
Sent: Wednesday, February 18, 2026 10:45 AM
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Subject: [pearson] inspecting chainplates on 1987 P31-2

 

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[George Dubose]

Well, if you want the best approach to replacing chainplates, I would watch Sailing Uma on YouTube, episode 474.

One doesn't have to go as far as they did, but there are some very useful tips on reinstalling and stopping leaks.

George/Skylark

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[David Lidrbauch]

As Guy described.   You will need to pull them to determine whether good or needs replacement.   It's worth having them checked by a shop who can magnaflux or otherwise check for hidden crevice corrosion not otherwise visible...

-David Lidrbauch

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[Kevin O’Brien]

Any corrosion condemns the chainplates. It’s not worth risking the rig; if you can see it, it’s time.

Kevin O'Brien

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[Edward Criscuolo]

I would go one step further. If you remove them, you should replace them. After all, some of our Pearsons are 50 years old!  The shroud chain plates are simple flat bar stock, inexpensive to make. Then it’s good for another 50 years! 

@(^.^)@ Ed

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On Feb 18, 2026, at 2:16 PM, Kevin O’Brien <kevin.mor...@gmail.com> wrote:



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[Dave Cole]

Nah, inspect, replace if required.  If they have held up for 50 years, they will likely last another 25.  

Buying stainless of guaranteed quality is not that easy. 

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[David Lidrbauch]

If you do need new

Metal supermarket in Woburn MA

Choose your metal type and grades and they will cut to your dimensions.   

Fairly fast and affordable

-David Lidrbauch

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[Kevin O’Brien]

I’m not sure this is the right approach.

Crevice corrosion occurs where stainless is exposed to water in a low-oxygen environment - and it’s microscopic. Failure is sudden and severe, it cannot be predicted, and it will bring your rig down.

Boats have been lost for failed chainplates, and assuming that the metal - which experienced cyclical loading for a quarter century - will last is foolhardy.

New 316L plates will give you at least a decade. Failing to replace your chainplates could result in a denied insurance claim, if they are found to be that old and not replaced. They could sink your boat. They could kill you or another person.

Spend the money and replace them. A full set of exceptionally oversized plates cost me $4500 just this past summer - it’s not that much, I imagine, on a much smaller Pearson.

Kevin O'Brien

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[Guy Johnson]

$4500.00 ??? I do hope you forgot a decimal point somewhere in there. 

If you're really worried, you can use dye to help expose flaws. 

Guy

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Subject: Re: [pearson] inspecting chainplates on 1987 P31-2

 

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[Dave Cole]

The problem is that the 316 you think you are buying may not be.

There has been big issues for years regarding inferior stainless.

So are you sure you are really getting 316L?  

I know the owner of one of the biggest fab shops in the midwest and this is a big issue.  The only way they reliably get around this is by buying from very reputable suppliers who supply traceable materials.  

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[George Dubose]

One of the doomsayers wrote about the stress of cyclic loading.

I believe when the boat is in the water and sailing the loading on the stays, shrouds and chainplates is much different than when the boat is on the hard with her mast standing. Owners who are too cheap or lazy to have their mast unstepped in the fall and store their boats on land are inviting this problem of cyclic loading and metal fatigue.

I also think that one if the biggest causes of mast failure is unmaintained or improperly tuned standing rigging.

George/Skylark

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[Kevin O’Brien]

Yes, $4500. I worked with a fabricator that I know and trust, and had 6 1/2” thick 316L custom external plates made, with countersunk bolt holes cut to the shoulder profile for 8 316 socket head bolts, run through to 1/2” G10 backing plates, epoxied to the interior of the hull. Each plate was electro and then hand polished, and I passivated them prior to final installation.

In my case, my brother in law is a robotics engineer, and had an existing relationship with the metal fabricator in question, which made it easier to find a trustworthy source.

It is your boat. Do as you like. Being aware of the failure points for stainless does not make one a doomsayer.

Kevin O'Brien

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[Jeff Griglack]

If you really want to not have to deal with crevice corrosion in the future, you probably should do what the late Patric Childress did on his boat "Brick House."  He replaced the SS chain plates with Titanium alloy.  Here is an article about it:  https://whereisbrickhouse.com/2019/10/25/titanium-chainplates-on-sailboats/

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[Dave Cole]

The biggest issue I have seen are deck leaks that rot bulkheads.  Then the chainplates are ripped right out of the bulkhead and through the deck. 

Dave

10M #26

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[Mike Butler]

Thanks for all the helpful comments. I will tackle this project later in April/early May depending on weather. I'll let the group know how it turns out.

Mike

31-2 #92

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[Mike Butler]

Update-

I removed the chain-plates from Vela a few days ago. I am happy to report they are in excellent condition. No corrosion at all in the area between the deck and the cabin liner. The flexible sealant definitiely prevented any moisture intrusion. The balsa deck core was dry, which I found very surprising. I cannot say for sure but I am speculating they were inspected about 15-20 years ago and reinstalled. I have two questions for this group. 1) I would like to seal the exposed balsa deck core before reinstalling the chain-plates. What do you recommend? 2) For a flexible sealant I am thinking is 3m 4200 or 3m 4000 suitable? If not is there a different brand/type you recommend?

Thanks very much.

Mike Butler

[Dan Pfeiffer]

I would remove the balsa around the chainplate slots for about 1/2 to 3/4" so it includes the screw holes for the cover plate and fill the resulting void with thickened epoxy.  I would use West System epoxy with a 406 or 404 filler.  Start by coating the surfaces with net epoxy (no fillers) then fill in the thickened epoxy.  Thickened to a heavy peanut butter consistency.  I'm sure there is a System 3 or Mass epoxy equivalent.  I know the West System so I reference that. 

Chamfer the top edge of the slot to better hold the sealant.  I would use BoatLife Sealer Caulk or 3M 4200 which are polysulfide.  Or butyl tape.

Dan Pfeiffer

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