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Old 09-07-2017, 16:05   #1
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Chain plates

Just purchase a 1978 Pearson 365 ketch rig. When should the chain plates and all the shrouds be checked ? The boat seems to be in very good condition.
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Old 09-07-2017, 16:33   #2
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Re: Chain plates

If you have no idea when it was "checked" or more importantly replaced last, then by all means check it. Hire a good rigger to survey it. Most manufacturers recommend a 10-year replacement anywhere south of the Mason-Dixon line; you can get a little more in northern latitudes, but by all means have it carefully looked over, and have a chainplate or two pulled and closely examined.
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Old 09-07-2017, 22:13   #3
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Re: Chain plates

Fwiw the industry standard life expectancy is 10 years on stainless wire rigging and 20 years on chainplates. Less in Panama, more in Newport, but no more than 30 even in Chicago.
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Old 10-07-2017, 00:37   #4
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Re: Chain plates

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Fwiw the industry standard life expectancy is 10 years on stainless wire rigging and 20 years on chainplates. Less in Panama, more in Newport, but no more than 30 even in Chicago.
Greg, where did you get an average lifetime for chainplates? I don't see how such could be formulated, for they come in such a huge variety of designs, materials and load distribution. surely you don't think your Ti plates will need replacement in 20 years, and my massive 2205 jobs are a bit older than that and show absolutely no signs of degradation. On the other hand, some that I have seen, with puny cross sections, bad angles, poor sealing etc are scary when brand new!

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Old 10-07-2017, 03:22   #5
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Re: Chain plates

I canít say as Iíve ever run across a fixed, recommended time frame in which chainplates should be inspected or replaced. There are just too many variables which affect their lifespan. And some chainplates can be shot in less than 5yrs, while others are still going strong at 50+

Given that it sounds like yours are original, & you donít (& canít) know their condition without fully inspecting them, then Iíd say that itís time to do so. Probably to include pulling them out for inspection, & then re-bedding them, after inspection or replacement.

The reasons for pulling them are that much of the damage which happens over time is due to crevice corrosion, & that tends to happen most in the sections of them which are in the deck. As water can lodge in the deck core when the bedding ages, & that area is also a spot where they tend to flex more than in other areas. Thus making them more failure prone there. Much as when you bend a piece of wire back & forth several times.

Sometimes the problems with them are quite obvious, even without pulling them. But with others, issues are impossible to spot without pulling them for inspection. This, along with polishing them a bit, & or checking them with dye penetrant. Since sometimes this is the only way short of x-raying, to spot any issues. And using a magnifying glass, along with a pocket microscope surely helps to spot issues in rigging as well. I got my pocket magnifier from Brion Toss, & love it!

Should you need to replace them, duplex stainless, as mentioned by Jim Cate, or titanium, tends to be a better choice than 316, or 304/306 stainless. As the former 2 metals are much less prone to stress cracking, or corrosion.
Also, should you need some new ones made, it usually pays to have them done by a fabrication shop which isnít part of the maritime mafia. As their rates will be a lot lower, since theyíre not a nautical or ďmarineĒ business. Though if youíre handy with a drill press & a few other tools, theyíre not overly tough to fabricate yourself.
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Old 10-07-2017, 06:40   #6
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Re: Chain plates

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Originally Posted by Jim Cate View Post
Greg, where did you get an average lifetime for chainplates? I don't see how such could be formulated, for they come in such a huge variety of designs, materials and load distribution. surely you don't think your Ti plates will need replacement in 20 years, and my massive 2205 jobs are a bit older than that and show absolutely no signs of degradation. On the other hand, some that I have seen, with puny cross sections, bad angles, poor sealing etc are scary when brand new!

Jim
Jim,

Ya I should have been more clear. 20 years is the mandatory maximum 'pull and NDT' age for stainless chainplates on inspected vessels by the USCG. Which really means you just replace them since a full round of testing is pretty expensive comparably.

Titanium has no corrosion/fatigue failure path, so short of mechanical damage they will last for ever. No testing required.

The thing is that even with no corrosion stainless work hardens and that can lead to failure fatigue even if they haven't started to corrode.
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