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View Poll Results: Composite or Stainless Chainplates?
Internal/External Composite Chainplates 10 40.00%
External Stainless Chainplates. 15 60.00%
Voters: 25. You may not vote on this poll

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Old 06-12-2021, 15:51   #16
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Re: Composite Chainplates or External Stainless Chainplates?

3. Neither. Ti
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Old 06-12-2021, 15:56   #17
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Re: Composite Chainplates or External Stainless Chainplates?

I had a bunch of Carbon available to make chainplates, since our bow beam, rudders, and davits are all carbon. I asked Kurt (the boat's designer) about it, and he said it would work very well, if I wanted to save very little weight, and spend 10 times the money on them.

According to Kurt, there really isn't much weight savings in using Carbon for chainplates. The way they're loaded, in tension, the numbers are apparently fairly close. Kurt said the savings in weight wouldn't be much, as compared to building it in glass.

Having said that. If I were suffering from epoxy allergies, I'd go with stainless. There's far less glassing to do, and less chance of a cock-up, in my opinion. Carbon doesn't go translucent when it's wet out, you have to have a feel for it, so you'd better trust the guy wetting it, or your chainplate is going to be crap.

When it comes down to it, the boat's not going to suffer from a few extra pounds in the chainplates.

My vote is for 316l Stainless. I wouldn't personally go for Titanium, but that's me. I don't see the cost/benefit analysis as working in your favour. The cool factor is there, but I don't see a real benefit.


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Old 06-12-2021, 16:12   #18
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Re: Composite Chainplates or External Stainless Chainplates?

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Originally Posted by tamicatana View Post
3. Neither. Ti
So... wooden chain plates? I’m lost.
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Old 06-12-2021, 16:35   #19
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Re: Composite Chainplates or External Stainless Chainplates?

Ti is symbol for titanium.
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Old 07-12-2021, 02:58   #20
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Re: Composite Chainplates or External Stainless Chainplates?

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. I wouldn't personally go for Titanium, but that's me. I don't see the cost/benefit analysis as working in your favour. The cool factor is there, but I don't see a real benefit.


Cheers.
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Ti will not rust, even if no oxygen situation as will rust inox. And is lighter weight for strength. You will never again have to replace if the structural attachment doesn’t fail. Fatigue tolerance of Ti is enormously greater than inox also
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Old 07-12-2021, 03:45   #21
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Re: Composite Chainplates or External Stainless Chainplates?

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Ti will not rust, even if no oxygen situation as will rust inox. And is lighter weight for strength. You will never again have to replace if the structural attachment doesn’t fail. Fatigue tolerance of Ti is enormously greater than inox also
That's all true. But silver is a better conductor than copper, and for most things, due to silver's cost, copper is good enough.

I respectfully submit that stainless, monel, or bronze, would be a more appropriate choice, given that most of us build on a budget.

If Titanium were easily acquired, and cost efficient, we'd see many more boats out there with titanium chainplates, rudder shafts, and prop shafts. I'd think the latter two uses would have a better argument for using titanium, but it never happens. There's far more chance of them corroding than the chainplate. Yet, I only ever see titanium chainplates, as bling I suppose.

I'd bet that bronze would be a very good choice as well, but it's not as clean, and doesn't shine as well as stainless and titanium, which I'd suggest is another reason it's not used for chainplates anymore. I'd bet the cost is much less than titanium, and about twice the price of stainless for the raw material. But it's softer, easier to work and seems to last forever.

PS, for those using bronze, it's better to use barstock than try to cast your own.

Horses for courses.

Cheers.
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Old 07-12-2021, 05:01   #22
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Re: Composite Chainplates or External Stainless Chainplates?

Don't need two for it. Sorry the pictures flipped..
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Old 07-12-2021, 06:06   #23
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Re: Composite Chainplates or External Stainless Chainplates?

While doing a little research, (10 minutes on google) it's come to my attention that there are different grades of titanium. One should be careful what one buys, as type 2 titanium isn't as strong in shear or tensile strength as 316 stainless.

People might want to know what they're getting into, and study the material closely. Titanium, like stainless, comes in different strengths and qualities.

Grade 2 titanium is similar to 316 stainless in many of it's qualities, whereas grade 5 titanium is somewhat stronger in tensile, but not in shear. I haven't researched much into either type, but I was surprised (though I shouldn't have been) to find there were different grades of titanium.

316 vs grade 2 titanium: https://www.makeitfrom.com/compare/A...50400-Titanium

316 vs grade 5 titanium: https://www.makeitfrom.com/compare/A...56400-Titanium

Here's 304 vs Grade 5: https://www.makeitfrom.com/compare/A...56400-Titanium

Finally, grade 2 vs grade 5 titanium: https://www.makeitfrom.com/compare/G...56400-Titanium

And here's a link comparing Grade 5 to 316 stainless, but only in a general sense. It's translated from Chinese, so the syntax isn't perfect.
https://www.shew-esteelpipe.com/news...-14469807.html

I disagree with this article, but I'm posting it out of an interest in balancing this post. He's against stainless, though thousands upon thousands of boats have them and don't generally have major failures: https://www.allatsea.net/the-worst-p...e-chainplates/

So one should perhaps quote the type of titanium he/she is comparing to 316 stainless, rather than making a global statement that titanium is a better material.

If you want titanium, I think that's great, but don't call your local supplier and just ask for titanium; know what you're getting.

Cheers.
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Old 07-12-2021, 06:45   #24
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Re: Composite Chainplates or External Stainless Chainplates?

For those interested in Bronze. GordMay posted this chart in 2011. If you want to read the thread: https://www.cruisersforum.com/forums...tes-52069.html

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Old 07-12-2021, 15:52   #25
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Re: Composite Chainplates or External Stainless Chainplates?

Re: different grades of Ti.

You mean, exactly like different grades of stainless? Or any other metal, for that matter?

But, since the question was about a multihull application… here is a multihull example

https://tulasendlesssummer.com/titan...ing-catamaran/
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Old 07-12-2021, 17:07   #26
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Re: Composite Chainplates or External Stainless Chainplates?

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Originally Posted by Chotu View Post
Ah! Thank you!

Maybe it’s not clear what a composite chain plate is.

This picture should clear that up.

It’s glass both inside and outside the hull, passing through a hole in the deck that is epoxied closed so there is no chain plate movement or leaking possible. Lighter and stronger than stainless. But seems to be a hell of a lot of work and problems that can go wrong if the employees make a mistake on them. Cheaper than stainless too, but not if I need to pay a 2 man team to do it.

No maintenance, no monitoring. They are a part of the boat itself.

Chotu,
What kind of attaching hardware does one use to affix the standing rigging to these chain plates, are the holes lined with metal or a bushing of some type?

I imagine there will be some wear at attachment points
Clevis pins and such.
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Old 07-12-2021, 17:26   #27
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Re: Composite Chainplates or External Stainless Chainplates?

I said Ti early on, because there has been a lot of bru haha in the last 10 years on here about how economical Ti has become. I know it's been expensive in the past. Maybe it has become hard to find in the last couple of years commercially? I have toured mills making ti plate and sheet.

Of course there are different grades of Ti, But dont get lost in the numbers. Many aircraft parts are made from "Commercially Pure" Ti. A40, A 50, A70 etc. The numbers indicate ~ Yield Strength. (the point at which it takes a permanent bend as opposed to springing back) I spent most of a career working with Ti and solving it's problems in manufacture from welding to superplastic forming etc. I would be very surprised you need anything more exotic than CP Ti for chainplate. (Commercially pure)

It's a troublesome material to work with, but in flat plate form like chain plates it's easy peasy to work with.

I wonder the cost of $2500 came from in that early post?
A quick look on line shows Ti to be quite expensive now. 12 x 18 x .25 thick at $800+ OUCH.
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Old 07-12-2021, 19:31   #28
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Re: Composite Chainplates or External Stainless Chainplates?

Composite chain plates don't need to be made out of carbon. S-glass has higher tensile strength than carbon. The advantage carbon has over glass is it's compression strength.
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Old 07-12-2021, 20:11   #29
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Re: Composite Chainplates or External Stainless Chainplates?

HA! I just looked up the quote I received from Allied Titanium on 9/23/2021 and it's worse than I remember.

200mm x 500mm x 8mm thick, Mill Finish, Grade 5 Titanium.
6 ea 12.5mm bolt holes, 1 ea 16mm clevis pin hole, 1 ea 19mm clevis pin hole.

$1487 EACH for a total of $2974.

10mm brought the price to $2052 EACH for a total of $4104

Crazy!

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Old 08-12-2021, 01:53   #30
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Re: Composite Chainplates or External Stainless Chainplates?

I’m an ex glassie, but I don’t own a boat and I have never laid up chainplates or such but I’m going to give you my 2 bobs worth anyway.
I sail on a 28’ tri that has composite chain plate and forestay fittings and I have talked to the owner builder about it.

Is the boat epoxy ?
If it is then you will have to use epoxy and so stainless may indeed be your best option.
If the boat is polyester or vinylester then use vinyl ester.
The advantage of composite fittings is the way they spread load out rather than on a few bolts which will leak, tangs going through decks will leak because the loads are so localised they will move around, it is inevitable.
By spreading the loads so broadly and by being homogeneous with the rest of the composite construction leaking from composite fittings isn’t an issue.
Having said that, installing composite fittings post construction is not without its problems and you need competent advice and tradespeople.
If you are a do it once do it properly kind of guy add value to the boat and go composite.
If easy and cheap is your thing go stainless.
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