Island Packet Chainplate Replacement

[Pauls]

A64, if you haven't, please check with the welder and verify details of the setup he used. Proper welding setup is a BIG deal with ti. Because it oxidizes so easily exposure to any oxygen while it is molten greatly weakens the weld. The ONLY safe way to weld ti is in an inert gas glovebox. There are a lot of welders who believe that they can tig weld ti, and it is true that the welds look good afterwards. But if you destruct them you will find them brittle and weak. So, ask the welder what welding approach he used. If it was anything but a glovebox, you may have pretty new chainplates that are not as strong as you'd want.

[Jim Cate]

Unqualified opinion follows:

While Il like the use of Ti in such applications, I'm not too impressed with a design that puts all the loads on 4 small welds, and in a material which has the reputation of being difficult to weld well.

Perhaps one of the resident gurus can comment on NDT methods for evaluating such welds at time of manufacture, and if that has been done on these weldments.

Jim

[toddster8]

Very interesting information. Thanks for these photos.

Many 70's era Ericsons were built with chainplates exactly like that. Including mine. Of those people who have extracted them from the hull - some were found wet, but I've heard of no flaws within the buried part. Some have failed at the deck penetration. (No way to inspect.) Lately, the consensus seems to be to leave the old chainplates in place, and use them as backing plates for new external chainplates. Some people have designed triangular-shaped plates to sink as many bolts as possible through the old cross-bar. (It also requires minor modification to the toe rail and hull/deck joint.)

They look OK to me - if you didn't know the boat previously had internal chainplates, you wouldn't look twice.

[a64pilot]

They were fabricated at Allied Titanium, a shop that of course welds Ti on a daily basis.
Yes, the loads are borne by the welds near as I can tell. I am not concerned about the welds, the are not pretty but do have good penetration, do not seem to have any porosity or contamination, contaminated Ti during welding I believe gives you some pretty colors, there is no color at all to these.

The Ti plates are dimensionally identical to the 30 yr old 304 ones that came out, 6/4 or grade 5 I think it's called is I believe stronger than 304 SS, and the 304 SS plates are well stronger than needed until they corrode, it's then that they may fail. They do not fail until very corroded.
The Ti will not corrode in my lifetime, I don't think.

In my opinion my 30 yr old SS plates looked pretty good from just a visual inspection, to me. If I had known they looked like that, I may have not had them replaced, just how do you know what they look like? Why did mine look OK after 30 yrs, when others have failed at much less than 30 yrs?
Only difference I can think, is my boat was obviously a Maria Queen most of her life and spent a significant time in Bath Maine, where I assume she lived on land for half the year, but then she went to Hilton Head SC for years and was day sailed by an older couple who sold her when they were no longer capable of sailing, but how many years did she sit before they finally sold? Next guy was afraid of her and she only left the dock in Daytona with a hired Capt, day sailing.
500TT on engine.

Maybe the chainplates that fail early are on boats that actually sail and get stressed, maybe it's partially stress corrosion?
Just thinking out loud.

[a64pilot]

A quick Google seems to confirm that stress corrosion cracking is an issue in both 304 and 316 steels to include the L alloys too, in a chloride environment, at both elevated temps especially, but also room temps.
So maybe, just maybe how the boat has been used has a bearing on how long the chain plates will last if made from 304/316 steels?

[model 10]

Originally Posted by a64pilot

They were fabricated at Allied Titanium, a shop that of course welds Ti on a daily basis.

Oh come on, those are not pro welds. I would not sign off those parts for an aircraft. I can do better and I am semi pro at best.

[missourisailor]

Originally Posted by Jim Cate

While Il like the use of Ti in such applications, I'm not too impressed with a design that puts all the loads on 4 small welds,

It's not "4 small welds" it is actually 8 welds per tang.
4 on the cross brace and 4 on the deck angle.

Although not glassed in, the deck angle is also sharing the load. In fact, I think that it is handling most of the load because the shroud is tensioned while the bedding is still wet.
The cross brace's glass strands are wetted and placed while the chain plate is being installed but not fanned out until tension has been applied.

So I've been told.

As far as the integrity of the welds, comming from the same background as A64, and there is no way that I would have any one but a type rated welder/shop make the welds. I know A64 has the same thoughts.

So I don't think that the welds are going to be the issue. The issue that I see is the stress cracks formed by work harding (wrong term but I can't think of the correct one right now). Can't tell you how many skin panels I've seen replaced because of cracks around the fastener holes.

But all in all, Ti might be the better material. but we won't know for another 15 or so years.

[missourisailor]

Originally Posted by Guy

Oh come on, those are not pro welds. I would not sign off those parts for an aircraft. I can do better and I am semi pro at best.

I've seen some butt ugly welds hold when pretty ones have failed.
That is what the NTD guys are paid to figure out.

[a64pilot]

Yes, but I'd bet money these were not tested, nor will be as they start going into the boat tomorrow.
X-ray is the only way I know of to really cert welds.
However as an old oilfield contract welded, I'm not worried, as long as there is no porosity, severe undercutting and there is good penetration, they ought to be fine. Yes I would like to have seen the row of pretty puddles, like is on my Ti Lightspeed bicycle, but oh well.

[Stumble]

Originally Posted by a64pilot

Yes, but I'd bet money these were not tested, nor will be as they start going into the boat tomorrow.
X-ray is the only way I know of to really cert welds.
However as an old oilfield contract welded, I'm not worried, as long as there is no porosity, severe undercutting and there is good penetration, they ought to be fine. Yes I would like to have seen the row of pretty puddles, like is on my Ti Lightspeed bicycle, but oh well.

I can't speak to what they are doing now, but when I was there AT had every part run thru both QC and QQ departments that were encouraged to find faults the other missed. The same shop that made those makes parts for Boeing, so while I can't say for sure (nor an qualified to comment on welding) I would trust them.

Originally Posted by a64pilot

The Ti plates are dimensionally identical to the 30 yr old 304 ones that came out, 6/4 or grade 5 I think it's called is I believe stronger than 304 SS, and the 304 SS plates are well stronger than needed until they corrode, it's then that they may fail. They do not fail until very corroded.
The Ti will not corrode in my lifetime, I don't think.

If they are 6/4 (The same alloy as G5) the UTS is around 130kps vs 70ksi for 316 stainless, and a UYS of 120ksi vs ~30ksi. So the chainplates are roughly four times stronger than the stainless they replaced.

[a64pilot]

Originally Posted by Stumble

I can't speak to what they are doing now, but when I was there AT had every part run thru both QC and QQ departments that were encouraged to find faults the other missed. The same shop that made those makes parts for Boeing, so while I can't say for sure (nor an qualified to comment on welding) I would trust them.









If they are 6/4 (The same alloy as G5) the UTS is around 130kps vs 70ksi for 316 stainless, and a UYS of 120ksi vs ~30ksi. So the chainplates are roughly four times stronger than the stainless they replaced.

They are 6/4. I knew that alloy was stronger, I did not know it was that much stronger

[a64pilot]

Mast was stepped yesterday, chain plates are going in today, except the aft stays, they are still installed and are supporting the mast, then once the others are in and set up, then the aft stays.
Videographer was there today and of course so I had to stand behind him and out of the way, they are going to correct the video.
Anyway I can see how it was made incorrectly, the videographer runs the show, has them positioned the way it will video orientation of the chainplate, they way they move to install it etc., a little overwhelming for the guy doing the work.
Anyway these are a few pictures of the way the glass lays on the chainplates

I asked why the Epoxy was red, was that brand just red? Answer is sort of obvious, they dye it so it's easy to ensure is all wetted out, with it clear it's tough to tell. I never knew you could add dye

[jimbunyard]

It isn't apparent in the pictures of either the new or old chainplates, but it appears that both the lower long bar and upper short angle iron are at 90 degrees to the chainplate.

If this is so that is likely why there is an issue with water intrusion; the chainplate should follow the same vector in both dimensions as the stay that attaches to it, if not there will be twisting forces as the loads try and take out the 'slack'.

Likewise I don't understand the use of the longer piece of bar at the bottom of the chainplate; the (secondary bond) strength provided by the unidirectional fiber at that point is only concentrated at the intersection of the long crossbar and the vertical chainplate. Even if the long bar is glassed in, the increase in strength will be less that ideal, again because of the secondary bond.

For maximum strength and rigidity, it seems to me the solution would be to quadruple the length of the angle iron, weld it to the chainplate at the proper angle to conform to the fore and aft angle of the stay, bed and bolt the angle iron to the existing original hull and deck joint, shorten the lower bar so that it just accommodates the unidirectional fibers, and glass that end after the mast is stepped and the stays loosely attached.

Of course this is 'a day late and (several) dollars short' and if the chainplates are on the same ultimate angle as the stays, the other suggestions are (mostly) irrelevant.

And since the new titanium chainplates as they are will likely outlast most of us and the boat as well, I guess I just wasted about 20 minutes...

[a64pilot]

There is no strength issue, at all, until the SS is severely corroded and simply breaks due to corrosion.
I agree the long crossbar is unnecessarily long, but it doesn't hurt being long, I'm sure it's long cause it got copied from a chainplate that had one long bar, but was cut making three chainplates out of one, could save a little money if a shorter bar was spec'd with a Ti plate I'm sure.
The angle of the plates is no issue cause the angle is bedded in with thickened resin which corrects for any misalignment.

No problem with thinking out of the box, sometimes people come up with a better mouse trap that way.

[JPA Cate]

We had to do a chainplate repair on our Standfast 36, and the load spreading tabs spread the load over about three feet parallel to the water line, and were about 3 ft vertically.

Ann