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The survey on the boat I have an offer on came back with a hairline crack on one chain plate. Are these fabricated or do you get stock from the manufacturer? Crealock-37. Do you normally just replace the one al all of them?
If one has a hairline crack, the others are probably about to fail as well. You replace chainplates as a set, not one at a time. Doing one at a time is penny-wise/pound-foolish, and can get you killed if one you didn't replace fails and the rig comes down.
You normally have to get them custom fabricated, unless the boat is still being made.
I pesonally never heard about a hair line crack in a chain plate But i'm sure it's possible. I did heard about it on turn buckles and other part of the rigging.
But it's really no big deal to change a chain plate, it's basically just a plate of stainless steel... unscrew the bolts and replace it, you could probably have one made up at a local machinist shop or something but in sure you could find a source on the internet.
(if the mast is still stepped, make sure too loosen the stays/shroud)
I assume you already read through the threads on the PS group about this?
Rumor has it for the six mast shroud chainplates, the factory parts are about $1000. Professionally done in Kemah, the whole job is $6000 (based on a boat that just did it here as part of a sale).
For some scary looking issues with older chainplates, check out the pictures on this SA thread (you'll have to log into their site to see the pics) (sorry for posting the link to a "competing" board, but the pics are pretty incredible)
Note that it did not fail at the actual weld, but where the metal was continuously encased by the deck ...And like mine leaking under the deck base plate. Mine also showed the same kind of crevicing, so they had to go ASAP.
I've seen the thread on SA before.
The good news here is the boat, a Crealock 37, has outboard chainplates. Access, at least on the outside is easier as is inspection.
While the chainplates are easy to get to on the outside, a lot of removal may be required to access them on the inside. That could add up hours pretty fast.
We made ours when we replaced them as the factory parts were not available. We bought 316SS flat bar (over $400, wholesale. 11 chainplates) but it was not available in exactly the same size as the original plates so we bought the next size up and had a machine shop mill them down ($150) to the correct width. We had to cut them to length, bend an angle into some of them and round the corners and drill the holes (had free access to metal shop), which took quite a bit of time. The stock you buy is not smooth at all, and to get a mirror finish is extremely time consuming so we had that done at a shop as well ($350). The point of this is that even though $1000 sounds high for a few pieces of flat bar, it's probably less than you will have into making them and it will take a LOT less time.
Actually, you want the polished to a mirror-like finish and the ELECTROPOLISHED to smooth the surfaces at a microscopic level... you do not want them ELECTROPLATED.
I have just made new chainplates for my Formos 41. I have access to polished SS and can give you a price for making the same for you, if you are interested.
No, it's to achieve a totally smooth surface with no microscopic crevices that will allow crevice corrosion to take hold.
Stainless steel does not rust on the surfaces exposed to oxygen, but they do corrode and fail in an anaerobic environment, which is usually the part of the chainplate that is encased in the deck.
I had the same problem with my Hudson Force 50. I had pulled the chain plates and had them repaired. They welded another thick piece of stainless over the crack and extened the repair so that at least one bolt was also included in the repair area. It works fine.
Is it worth risking your rig, deck, crew and most importantly SELF, just to save the few extra bucks new chains would have cost you? It isn't that expensive to make new ones up. I would think it would be less than merely painting the bottom of that monster (just how many acres of wetted surface DO those boats have?).
i know this is an older thread but people may still be researching doing their own chainplates. i replaced all 8 of mine on my Alberg 30 this winter. i used 316ss and made them out of larger stock than factory units. Total cost was $80.00. that price included all the material. i was able to make all 8 from a 6ft piece of 1.5"x6'ft piece. obviously it would have cost more if i had someone else do it but i enjoyed the experience. i only polished mine...no plating. the factory 304 units lasted 40yrs so i figure my new much thicker and wider units should last me quite a while!
Thanks for the info/correction. I am sure whatever the additional process is you could tell from my post that I had chosen only to polish the chainplates I made. I made this decision based on chainplates I removed and what material I decided to make the new ones out of. Only one of my orginal chainplates showed any signs of crevis corrosion and it was minimal at that. All others had some rust staining but that was about it. Those were 40+ yrs old. My new ones are 3/16" thicker, 1/4" wider and polished over the orginals. Original made great backing plates! I felt that there was no addition processes necessary. Time will tell!
electropolishing is not necessary and does nothing to protect the stainless. mirrior mechanical polishing is the best. any type of polishing, be it mechanical or electropolishing will expose the free iron on the surface and it will rust if exposed to moisture. in addition to the electropolishing process most all parts are passivated and allowed to air dry before returned to the customer. it is the Passivation of the stainless that removes the free iron from the surface and should be done to all stainless parts. Passavation can be done to your parts by soaking in cirtus or nitric acid. soaking in Spotless Stainless will passivate the parts just as well.
I think that the members here are referring to passivation when they say electropolishing. From what my electropolisher told me about the process, passivation is an (the) integral part of the process. The combination of electricity and a nitric acid bath is what gets the iron out to a decent depth.
Also, I beg to differ about it doing nothing - the parts I had done years ago still look the same as the day they were installed. That doesn't happen when they are merely wheel polished and buffed. In that case they start out looking the same but it only lasts a couple of years before they start to lose their gloss and the old brown stains start to make an appearance in corners and on edges and particularly on welds.
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