Chain Plate Testing

[crazyoldboatguy]

Greetings,

I am restoring a John Alden designed 47' auxiliary ketch which was built just after WW2 in Chile. I will likely re-install the 12 original bronze chain plates but am considering having them tested. They look fine at this time, having spent most of its sailing life in fresh water and having not been exposed to any stress or weather since probably 1980. They are about 3/8" thick and 2" wide and about 2' long. There are no obvious defects or deforming at the shroud attachment points

Any suggestions about testing would be appreciated. I could do a dye test or have them x-rayed, I suppose, but I wonder if I am over-thinking this.

Thanks

Daniel McNeil

[roverhi]

Bronze is pretty much good for life. Doesn't have the problems with crevice corrosion that SS does. Pull them, clean them up and inspect carefully. lf no flaws, reinstall them and they'll be good for another 60 years.

[crazyoldboatguy]

Originally Posted by roverhi

Bronze is pretty much good for life. Doesn't have the problems with crevice corrosion that SS does. Pull them, clean them up and inspect carefully. lf no flaws, reinstall them and they'll be good for another 60 years.

Thanks, roverhi. That is my feeling as well. I am just covering the bases and thought I would toss it to the forum to see if there were thoughts to the contrary. The chainplates look fine - having spent most time in fresh water, not immersed, I would expect nothing else.

Fair winds

[HappyMdRSailor]

I wouldn't call you crazy if you followed roverhi's advice...

Maybe old...

but not crazy...

[skipmac]

I will ad my own endorsement to that opinion. Clean them up, inspect with a strong magnifying glass and you're good to go.

[crazyoldboatguy]

Thank you all for responding. I already knew the answer for the most part but have been doing some research into it and thought I would post here to get some feedback.

[a64pilot]

If they are removed, I'd at least dye-pen them, but I have the equipment so it wouldn't cost me.
At least look good with a 10X magnifying glass and if you find any suspected cracks go further

[crazyoldboatguy]

I could look into the dye testing stuff. I used to do a lot of that testing when I was a welder. I haven't used it in 35 years so am not up on the current technology. My memory is that it is made up of three spray cans. One is a cleaner (methyl ethyl ketone, if memory serves), one is a penetrating dye (red) and one is a white "developer". Once the material is clean, the dye is sprayed on and then cleaned off with the MEK after the suitable waiting period. Once the metal is cleaned then the white "developer" is sprayed on. The red dye still in pits and cracks then is wicked up into the developer and shows as dots or lines where the defects are.

No other equipment is needed, that I can recall. However, as said, that was 35 years ago. Have things changed? Is that dye test still used? I used on exclusively on steel - does that dye test work on bronze?

So many questions.

Thanks

[a64pilot]

Simple dye pen is still exactly what you describe, for steel though a mag particle version of the dye is available, and graduate level of dye pen is to use a black light visable dye, a tiny crack you can't see the red line with, the black light will bring out.
But the plain ole dye pen is still exactly what you describe, no changes.

On edit, Dye pen works on all materials that won't absorb the dye of course,(won't work on wood for example) even plastic. That's one reason its used so often.

[crazyoldboatguy]

Cool - thanks

[UNCIVILIZED]

If you want to get crazy about it, you could always put them under a microscope, both before & during the dye penetrant testing, to check for cracks, but also to get a good look at the grain structure of the metal. For the latter, you could even open up a couple of the bolt holes a size, & peek at the metal inside of the holes, although it'd take a different kind of magnifier.

I have an older version, but am definitely a fan (and not just for working on boats, it come in handy for inspecting a lot of metallurgical type items) - see "Riggers Microscope" Brion Toss Yacht Riggers, Sailboat Rigging::Rigging Tools
Mine's a fixed 50x, & literally the size of a ballpoint pen. With a tip made out of clear plastic which is threaded on, so that you can precisely adjust the viewing distance to that which you're looking at. And as a perk, the clear plastic lets in a lot of light to aid in viewing things.
Fiber optics/Bore scopes work too, & some can even be hooked up to a recorder, as well as your tv/computer monitor, so that you can record all that you see, as well as having a record of things to go back & look at, if you have any nagging doubts.

Plus, for some "Winter Reading", break out a copy of Skene's or similar, to make sure that your chain plates have a bit extra metal in them, above & beyond what's called for.
But it sounds as if you've got it pretty well under control, & if you're well versed in dye penetrant, then you know the kinds of areas which cracks like to start in to begin with.

[HappyMdRSailor]

They got the stuff on Amazon cheap... here's the pen, look for the prep and developer...

http://www.amazon.com/Dye-Penetrant-.../dp/B00868S6TK