Titanium Chain Plates

[Stumble]

Originally Posted by a64pilot

6/4 Ti is not significantly stronger than 300 series Stainless by size, it is by weight of course.
I had one of our Aerospace Engineers look that up for me, assuming 316 in the half hard condition and the Ti not hardened, it's a wash on strength. If you use Grade 5 Ti, the other grades are not as strong as 316 half hard Stainless. That surprised me too, always heard Ti was magic
Weight savings on Ti is not all that much, it's only about 1/3 over steel, so if you have a 9 lb steel chain plate, it's going to weigh about 6 in Ti.
Only real disadvantage I see with glass or carbon fiber plates is wear and impact resistance, clearly it will never "rust" and can easily be made strange enough.
I think steel is just too easy, is the established practice and why not if your a boat manufacturer?

I went Ti for several reasons, mostly because it's turn key, I send chainplates that were removed from another IP 38 to Allied Ti and ask how much? Then a well established manufacturer makes and send them to me.
I could have made them myself at work, bought the Ti, had it water jet cut, I'd have to have the welding outsourced though. But it would have been a lot of work and time I don't have, and I'm Retiring, so I use work assets rarely.

One day my boat will be sold. If you were looking to buy, would you trust homemade chainplates that are glassed into the hull and cannot be inspected, or ones made by Allied Titanium?

Labor to R&R chainplates on an IP is excessive, about $8,000 to have it done by a Pro. So I never want to have to worry about them again.
Chainplates that can be accessed without too much work, I don't think warrant Ti in my opinion.
I guess point of my post is that turn key Ti plates are a little more than half again what SS ones cost, not five times as much or so.

A64,

I am not sure what numbers you were looking at but the UTS for 316 is around 84ksi versus G5 titanium at 138ksi. The G5 is far stronger size for size.

[Suijin]

Originally Posted by a64pilot

One day my boat will be sold. If you were looking to buy, would you trust homemade chainplates that are glassed into the hull and cannot be inspected, or ones made by Allied Titanium?

Labor to R&R chainplates on an IP is excessive, about $8,000 to have it done by a Pro. So I never want to have to worry about them again.
Chainplates that can be accessed without too much work, I don't think warrant Ti in my opinion.
I guess point of my post is that turn key Ti plates are a little more than half again what SS ones cost, not five times as much or so.

I walked into the metal fabricator's shop yesterday and he was working on a set of new chainplates for an IP38. Dear lord, I did not realize that they were glassed into the hull like that. Yep, titanium seems not only wise but downright mandatory in that configuration.

[Jim Cate]

Originally Posted by 44'cruisingcat

It depends on how they are done, but they can certainly be fixed. Although I'm not sure how you'd break them.

No advantages? Unless you consider no corrosion ever, no leaks, no rust streaks, and that they'll last the life of the boat to be advantageous...

I'd never willingly have metal ones again.

This makes sense to me, especially the leak issue. Not having to renew caulking, nor worry about hidden water intrusion damage to timber bulkheads or knees (as in many designs) seems to me to be a huge advantage.

And putting enough CF into the build that they are very nearly literally unbreakable isn't hard or too much extra expense.

Jim

[Cheechako]

Originally Posted by kentobin

Hello,

I am planning on going with some titanium chainplates but one of the issues is what size should I make them? Titanium is stronger than stainless so there is no reason to make the new chainplates the same size as the old ones especially since I could also reduce the cost. I'm currently not sure how to determine what size I need without hiring an engineer or naval architect.

Did you go through this design process and if so what are your words of wisdom?

Thanks in advance.

Ken

A couple considerations:
Bearing area: The rigging pin is bearing inside the chainplate hole. So I wouldn't personally go thinner. Go narrower or etc instead. Ti is very abrasive stuff, you'll just be wearing grooves in the pins. (?)
Alloy: Not sure if it's any cheaper, but Ti50 or Ti70 are both strong like stainless or more. If they may be cheaper than 6al4V ....maybe it's an option.
Finishing: I probably wouldn't bother paying for a great finish on Ti, it weathers into a dull grey pretty fast usually.
Alloy: One advantage of commercially pure Ti35, 50 or 70 is it drills fine. I'd rather drill it than SS myself as it doesn't work harden like SS destroying the bit with one error.
I have to say though, from the numbers I'm seeing, Ti seems awful expensive. $10 each for Bronze, vs $435 for Ti?


BTW, Someone mentioned 316 half hard. 1/2 hard is terribly hard to work with in 300 series alloys I've seen, it's cold worked and hard as nails. With that much cold work it may become magnetic also.

[Cheechako]

Originally Posted by 44'cruisingcat

It depends on how they are done, but they can certainly be fixed. Although I'm not sure how you'd break them.

No advantages? Unless you consider no corrosion ever, no leaks, no rust streaks, and that they'll last the life of the boat to be advantageous...

I'd never willingly have metal ones again.

Maybe ask the Americas Cup boat that broke completely in half in light air about how you'd break them, or whether to believe the strength numbers.... :>)

[44'cruisingcat]

Originally Posted by Cheechako

Maybe ask the Americas Cup boat that broke completely in half in light air about how you'd break them, or whether to believe the strength numbers.... :>)

It's chainplates we're talking about, yes? Did the chainplates break?

[Cheechako]

Originally Posted by 44'cruisingcat

It's chainplates we're talking about, yes? Did the chainplates break?

No but the material did even though probably millions were spent on engineering!

[44'cruisingcat]

Originally Posted by Jim Cate

This makes sense to me, especially the leak issue. Not having to renew caulking, nor worry about hidden water intrusion damage to timber bulkheads or knees (as in many designs) seems to me to be a huge advantage.

And putting enough CF into the build that they are very nearly literally unbreakable isn't hard or too much extra expense.

Jim

Thanks Jim, that's right. Mine are fibreglass, built up of layer of uni glass. Each layer could hold nearly a tonne and there are 24 layers. On a 6 tonne boat. I can't see them breaking.

Each one took about 4 hours to lay up. Cost of materials isn't much. Uni glass tape is cheap and maybe a couple of kilo's of epoxy.

Labour costs might be high for the mass producers, but you wouldn't think it would hurt lower volume builders.

[44'cruisingcat]

Originally Posted by Cheechako

No but the material did even though probably millions were spent on engineering!

Millions were spent on making a boat as light as possible. You don't do that with chainplates for a cruising boat.

[Stumble]

Originally Posted by Cheechako

No but the material did even though probably millions were spent on engineering!

And the safety factor was probably set at 1.001:1 with a maximum wind speed of 22kn and wave height of 1.25m.

Fall anywhere outside those parameters and the boat was going to collapse. But anyone who uses those numbers for anything but the AC should probably be shot for incompetence. It's like when people reference the VOR for failing keels. Well shure they fail, but they were only designed to last 80,000nm. Hit them just once with a crab trap, and pop goes the keel strut they weren't designed for it and will predictably fail.

Maximum level race boats are terrible examples of failure, the safety margins are pretty much eliminated, there is no room for error, and any little deviation from expected will result in substantial damage.

[Stumble]

Originally Posted by Suijin

I walked into the metal fabricator's shop yesterday and he was working on a set of new chainplates for an IP38. Dear lord, I did not realize that they were glassed into the hull like that. Yep, titanium seems not only wise but downright mandatory in that configuration.

The IP chainplates are so convoluted we seriously worked on a set of bolt together ones instead of welded. The fabrications and shipping cost differences were substantial.

[panamadean]

I plan to replace my chainplates with grade 5 titanium. I broke the port lower aft shroud chainplate at the hull to deck joint on my 1989 Island Packet 35. I was wondering if bolting might be more practical than welding for attaching the chainplate to the right-angle metal piece immediately under the hull to deck joint. I was surprised to see that there has already been some serious thought about a bolting method. I am interested to hear more thoughts on this.

[a64pilot]

I’d much rather have fiberglass chain plates than Carbon. Reasoning is how aggressively carbon fiber is corrosion wise to Stainless steel. Fiberglass is inert I think corrosion wise, and there just isn’t much to gain with Carbon over glass for this

[a64pilot]

OEM IP chainplates are one piece and installed prior to the interior of the boat. To install one piece chainplates would require removal of the bulkheads and just isn’t done or almost never done.
Replacements will be in three separate pieces, just like the aft chainplates are. Shipping is minimal, less than $100 I’m sure but don’t remember. I would not go to bolted as I don’t see any advantage and your giving the installer something new, and you’ll probably pay more for them to learn something new.
Some installers are apparently discouraging Ti now, I can only assume it the loss of repeat business cause except for being just a little lighter there is no installation difference.
The plates sit flush against the hull and I don’t see how a bolt head or nut would work unless countersunk

[GordMay]

Greetings and welcome aboard the CF, panamadean.