Do you think I should replace this?

[Dougtiff]

Yep, Stainless steel for chain plates can be a challenge, so many types, if you really want to do it right use BRONZE, O.K., it costs more, but by golly you don't hafto worry bout them anymore, if your going to keep the boat long time it pays.

[hamburking]

I'd get a better look first by cleaning it up with steel wool. A good scrub with steel wool will take off all the surface goop, and then you can actually see if there is a crack or serious corrosion to be concerned about.

[Cadence]

Originally Posted by hamburking

I'd get a better look first by cleaning it up with steel wool. A good scrub with steel wool will take off all the surface goop, and then you can actually see if there is a crack or serious corrosion to be concerned about.

Sorry, I wouldn't want to see steel wool anyplace close to anything onboard.

[delmarrey]

Originally Posted by Cadence

Sorry, I wouldn't want to see steel wool anyplace close to anything onboard.

Yeah, some boat owners scare me.

As for the OP's chainplates. I'm surprised that a 38' ketch would have plates that thin. Personally I would go with 1/2" 316 SS. As well, I'd be checking the core of the deck around the chainplates to make sure it is DRY and SEALED.

[gmasichuk]

There is a test called dye penetrant testing. It's considered Non- Destructive. I am a certified level II. I can perform and evaluate the test. The kits can be purchased at any weld supply store. Very simple to use. Clean the area with the supplied cleaner. Let dry . Spray on the penetrant (dye). Let sit for approx. 10 minutes. Wipe off with a dry clothe which has been lightly sprayed with the cleaner. The cleaning process gets the surface clean. You cannot "wash off the surface". Last is to spray lightly with the Developer. It's a wet powder that indicates pits, cracks and fractures that are almost impossible to detect with the naked eye. There should be a you tube video to reference.

[bletso]

There are 10 single chainplates and 2 double chainplates. Using a thicker material would be easier to fabricate, (no welding on the bar with good wear surface for the clevis pins) cheaper, and stronger. The main mast is 58 ft, (52 from the deck) and the mizzen 35 ft.
1/2 inch X 2 316 is $300 which is enough for three and all it would need is drilled and shaped.

At this plate's location I do have some core issues which I am addressing as well. It is scary to think what could have happened in a good blow at Murphy's choosing.

Bronze sounds good but which alloy? There are so many with so different properties.

Upon cleaning and closer inspection, I see at least 4 cracks and it is beyond even thinking of welding. The appear to be stress fractures around the top mounting hole.

Actually, I work in NDT, i.e. EC, UT, Mag particle, and dye.

[gmasichuk]

Good deal. You can see all those cracks pretty well . Good luck on the rebuild .

[alctel]

Originally Posted by bletso

One thing I have no idea about is the original has a thick area where they put the clevis pin through. It looks like they used 1/4 in stock and then welded a 2 in washer either side at the top. Is that necessary or is the 1/4 or even 5/16 stock good enough? I noticed that all the "stock" chain plates i have seen on the web appear to just use rectangular polished stock.

Mine is like that. I am replacing next year as a precaution and replacing all of them with straight ss the width of the washer ends.

[Rhapsody-NS27]

absolutely no doubt that chainplate needs to be replaced.

I just replaced mine and discovered when removing the old ones there was a crack that broke one where only one bolt was holding a shroud.
Here's what I had. Rhapsody: Check Your Chainplates

[bsurvey]

replace ALL of them, 316 stainless and bed them in 3M 5200. you were lucky

[bletso]

Originally Posted by Rhapsody-NS27

absolutely no doubt that chainplate needs to be replaced.

I just replaced mine and discovered when removing the old ones there was a crack that broke one where only one bolt was holding a shroud.
Here's what I had. Rhapsody: Check Your Chainplates

Ouch, talk about luck.

[Reefmagnet]

Originally Posted by gmasichuk

There is a test called dye penetrant testing. It's considered Non- Destructive. I am a certified level II. I can perform and evaluate the test. The kits can be purchased at any weld supply store. Very simple to use. Clean the area with the supplied cleaner. Let dry . Spray on the penetrant (dye). Let sit for approx. 10 minutes. Wipe off with a dry clothe which has been lightly sprayed with the cleaner. The cleaning process gets the surface clean. You cannot "wash off the surface". Last is to spray lightly with the Developer. It's a wet powder that indicates pits, cracks and fractures that are almost impossible to detect with the naked eye. There should be a you tube video to reference.

Stuck in the middle of nowhere? In the old days this was done by soaking a part in kerosene (diesel would substitute) for a little while, wiping it dry and then lightly sprinkling talcum powder over suspect areas.

[ex-12m-guy]

Type 316 stainless steel is notorious for crevice corrosion problems. We stopped using it years ago on large SWRO machine installations and switched to "Duplex alloy" stainless steel.

If you have a fat wallet, investigate having the new chain plates fabricated in duplex alloy.

A web search on "duplex alloy stainless steel" will yield a variety of vendors.

[Rustic Charm]

Originally Posted by bletso

I started sealing my chainplates which go through the main deck. I had leaks. I decided to pull them all the way out and do you think perhaps I had better change this one?

Really sobering to find one like this. Unlike a lot of designs, my chain plates aren't bolted to the outside of the hull, but through the deck inboard of the cap rail. In the cabin they are covered with decorative box type affair. Even leaks are not readily seen.

Unless this is cracked or eaten away, which I can't spot in the picture, it looks fine to me. Clean it up and put it back. The pin hole looks good too. It looks like it's just surface rust?

[Rustic Charm]

Originally Posted by bletso

There are 10 single chainplates and 2 double chainplates. Using a thicker material would be easier to fabricate, (no welding on the bar with good wear surface for the clevis pins) cheaper, and stronger. The main mast is 58 ft, (52 from the deck) and the mizzen 35 ft.
1/2 inch X 2 316 is $300 which is enough for three and all it would need is drilled and shaped.

At this plate's location I do have some core issues which I am addressing as well. It is scary to think what could have happened in a good blow at Murphy's choosing.

Bronze sounds good but which alloy? There are so many with so different properties.

Upon cleaning and closer inspection, I see at least 4 cracks and it is beyond even thinking of welding. The appear to be stress fractures around the top mounting hole.

Actually, I work in NDT, i.e. EC, UT, Mag particle, and dye.

OH, now i've seen that second photo I'd definitely replace that. That's not good at all.