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Old 22-07-2017, 11:51   #1
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Island Packet Chainplate Replacement

Been quite a bit of talk about how IPs chainplates are sort of an end of life item for the boats.
My boat becomes a Florida antique this year, she celebrates her 30th this year, so for her birthday I'm having her chainplates replaced.
I thought I'd start this thread with sort of a photo essay to show and try to explain what all is involved and costs etc.
All boats that I have head of go with Garhauer manufactured 316L replacements, and they are good I'm sure and have an expected life limit of about 15 yrs. now of course they may last much longer, but may not too and they would be very, very difficult to inspect, so to be sure your safe, the 15 yr life limit, or recommended replacement interval was established.
I went a slightly different route and had mine made out of 6/4 Titanium, which should have no realistic life limit, not as expensive as I brought it would be.
Anyway a few pictures to try to explain the process.
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Old 22-07-2017, 11:55   #2
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Re: Island Packet Chainplate Replacement

Can you please explain what exactly causes the issue in the first place?

Thanks
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Old 22-07-2017, 11:56   #3
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Island Packet Chainplate Replacement

First every little thing needs to be removed from the inside of the boat, cause they are going to be grinding fiberglass inside of the boat. That took us about three days to pack up everything and take it all to a rental house in a Prius.
Colin Mack has assured us he is going to buy a large box trailer so that we can take everything back in one shot by borrowing his truck, he is doing enough of these replacements to justify it, and it will make life a whole lot easier for cruisers to have a place to store all their stuff while the work is being done.
Then a lot of furniture has to be removed, but not as much as I thought. We found out my old chainplates had been leaking water, something that air had thought as I had not resealed them, a common problem from my understanding.Click image for larger version

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Old 22-07-2017, 12:17   #4
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Re: Island Packet Chainplate Replacement

Quote:
Originally Posted by Kenomac View Post
Can you please explain what exactly causes the issue in the first place?



Thanks


Didn't expect that question but I'll try.
In my opinion, gotta preface it with that, cause this is after all my opinion.
It was a mistake in design, or maybe more clearly maybe a mistake in manufacturing.
See IP's main chainplates are not three separate pieces, but one large monolithic piece welded together. Then I believe the idea to make them incredibly strong was to encapsulate them into the hull, spreading the load over likely 20 or 30 if not more sq Ft of hull.
However as we now know if you seal Stainless Steel and do not allow it to come into contact with Oxygen, it corrodes, and of course if you let it get wet, it has to accelerate the process.
Both can happen with an IP chainplate design, theoretically if your real careful and keep up with them being sealed, you can keep them dry, but was the previous owner?
The replacements are not encapsulated like the original and are individual pieces, to go back with one monolithic chainplate would require removal of the bulkheads as well, and that would be a whole lot more labor and isn't warrantied.
Now one would of course think that by making them into individual pieces, as well as they way they are glassed in, you lose strength, and I have to believe that as well.
However before I set out on this I asked the Aeronautical Engineer I had working for me to analyze it. His speciality is Structures, and he has his FAA Structural DER, so he knows his stuff.
Just happens to be an avid sailboat racer as well.
Anyway the loads that he calculated and the strength of the hull to deck joint and they way they are glassed back in give in excess of a 7 to 1 margin, which makes it acceptable for aircraft, and I assume a boat.

The rear stay chainplates from the factory are individual pieces.
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Old 22-07-2017, 13:58   #5
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Re: Island Packet Chainplate Replacement

The fact that oxygen starved stainless corrodes is not a newly discovered fact. IP should have known that.
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Old 22-07-2017, 14:10   #6
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Re: Island Packet Chainplate Replacement

Where are the chainplates in your photos?
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Old 22-07-2017, 14:54   #7
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Re: Island Packet Chainplate Replacement

Thanks for the explanation.
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Old 22-07-2017, 15:46   #8
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Re: Island Packet Chainplate Replacement

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Where are the chainplates in your photos?


Those pictures that you can see bare glass, they are there, inside of that glass
Have to cut / grind them out.
I hope to take more pictures as the job progresses and hopefully it will become more clear then. I can see the tails of them, and if you look at the glass you can see the unidirectional glass strands that actually hold the plates in, but likely can't in an IPhone photo.
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Old 22-07-2017, 16:02   #9
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Island Packet Chainplate Replacement

Quote:
Originally Posted by contrail View Post
The fact that oxygen starved stainless corrodes is not a newly discovered fact. IP should have known that.


There are all kinds of different skills required in designing and building something as complicated as a boat.
I can only assume there was no metals expert, I know the correct name, just don't ask me or my IPad to spell it.

I have run into all kind of screw-ups in some very experienced aircraft manufacturers, and you just have to ask, what were they thinking, how could they have done this?
Well sometimes what it is, is they messed up one, but got the other
999 things right, but it only takes one to be infamous.

My guess and it's only my guess, is that the risk of chain plate leaks was underestimated.
Likely if they could have always been kept dry, lifespan may have been 50 yrs or more? Mine are 30, have been leaking lord knows how long, and haven't broken that I know of
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Old 22-07-2017, 16:28   #10
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Re: Island Packet Chainplate Replacement

When you get them out could you post some pics of where they were buried in glass please. Ditto of the chainplates themselves.And if there’s no obvious cracking in them, perhaps you’d be up or using some dye penetrant on them for a better look?It’d be interesting to see what sort of shape they’re really in.

Also, if it’s not prying too much, it’d be good to know where you’re having the Ti ones made, & what their cost is. Including a cost comparison for new stainless ones (polished or otherwise).With specifics on what particular metals are being used, or were quoted for.

Thanks, & good luck with this.


PS: I'm sure that a lot of folks at IP knew that the chainplate "mounting" design would cause issues, but that someone in accounting or management said to build them that way. As to why, who knows. But such decisions ain't that uncommon as we all know.
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Old 22-07-2017, 16:42   #11
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Re: Island Packet Chainplate Replacement

You probably thought about this but you can bolt new chainplates to the old steel in the hull. Cut the old chain plates off at the deck, drill and tap holes into the imbeded steel in the hull. It's what I did to our Seafarer. What you are spending for repairs would not be worth it for our boat, or our monthly budget!
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Old 22-07-2017, 17:13   #12
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Re: Island Packet Chainplate Replacement

Maybe I miss read it. But did you say you were not encapsulating the new chainplates. And why.
Thanks
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Old 22-07-2017, 17:24   #13
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Re: Island Packet Chainplate Replacement

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Originally Posted by Kenomac View Post
Can you please explain what exactly causes the issue in the first place?

Thanks
Ignoring inspection and maintenance of the chain plate cover sealant allows water to enter resulting in corrosion of IP chainplates on boats older than 1998.
Newer IP's have no problems with chain plates.
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Old 22-07-2017, 17:32   #14
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Re: Island Packet Chainplate Replacement

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Ignoring inspection and maintenance of the chain plate cover sealant allows water to enter resulting in corrosion of IP chainplates on boats older than 1998.
Newer IP's have no problems with chain plates.
How was the design changed post 1997?
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Old 22-07-2017, 17:46   #15
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Island Packet Chainplate Replacement

I'll try to answer the questions, if I miss one, remind me, it wasn't intentional.
When I first contacted Mack Sails about the job, at least a year ago, I was told the job was about $10K with about $2K of that being the plates themselves.
I think but am not sure that having them made from 6/4 Ti was only about $3K, but don't quote me as I have forgotten, that's money spent and if I start worrying about money spent, well this boat thing is going to make me worry more than I want to if that makes sense.
Anyway I told them I wanted the chainplates bead blasted, not polished. I didn't want them to look like SS, they aren't.
I will take photos as the job progresses. We were supposed to step the mast Fri., but the step wasn't back yet from being hard coat anodized. Mast needs to be in to firmly hold chain plates in position while the epoxy cures, but I had mast pulled to go through everything, lights, wiring, sheaves, etc.

Yes you can mount external chainplates, no real reason not to I guess, just I think it would hurt resale and make the boat look odd, but I think it would function just as well.

Mack Sails does not encapsulate the new plates, encapsulation is I believe a big reason they need replacing, no advantage to encapsulation, and it will hold water against the plate and starve it from oxygen, not encapsulating will keep them dry and exposed to oxygen.

Likely having them made from Ti won't really mean much, likely a 316L plate would last at least 15 yrs, and then boats 45 years old, how long will she last, how long do I need her to? But the Ti is stronger, will last almost indefinitely, and is very noble, very unlikely to have any corrosion issues, and if the difference in cost only adds 10% to the job, why not?

1998 and newer IP's plates are made from 316L which should last longer than 304, but according to our metals expert, it's not as much different as we would think, that 300 series SS is awful close in corrosion resistance and strength, I had always thought 316 was much less susceptible to corrosion but significantly weaker than 304. Just isn't the case, he showed me the charts in his Engineering manual.
I would say it's safe to say that the newer IP's haven't had any problems, yet. Of course until you lose a mast most often, you don't know of any problems. I believe there have been a few chainplate failures that did not cause any other damage.
Even the 316 will corrode, just hopefully it will add years to the life, I don't know enough to know.

Newer boats have of course addressed a lot of the problems of the older ones, like aluminum tanks for instance.
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