EricHasAnEricson
Member II
Any leads on where I might find a replacement aft chainplate? Mine is looking pretty bad. I'm glad I noticed it before losing the whole rig.
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E38-200 replacement aft chainplate
- Thread starter EricHasAnEricson
- Start date
I would talk to a local small metal fabricator who likes little projects. Take the old one in and also make a careful drawing of the tang with the angle of the bend well noted. Use precise measurements and measure twice, as the saying goes.
Honk down on the mainsheet after setting up the toping lift tight, or if no top. lift, temporarily lead the main halyard to a stern cleat with a connecting piece of line. That will hold the rig just fine while you source a replacement tang.
I suggest a gnome to work inside the transom to undo the nuts; maybe that's you. A helper anyway.
When we took this part off during our re-fit/repaint, my wife did the outside part and I did the inside work with the socket wrench after crawling way.... back in the stern. Occasional swear words will help, some, a little bit....
Also --Contact these guys too for a quote. What used to be called "high tech" is more common now. https://www.alliedtitanium.com/prod...6&Search=Search&S_UCatalogue=74&S_UMaterial=1
Honk down on the mainsheet after setting up the toping lift tight, or if no top. lift, temporarily lead the main halyard to a stern cleat with a connecting piece of line. That will hold the rig just fine while you source a replacement tang.
I suggest a gnome to work inside the transom to undo the nuts; maybe that's you. A helper anyway.
When we took this part off during our re-fit/repaint, my wife did the outside part and I did the inside work with the socket wrench after crawling way.... back in the stern. Occasional swear words will help, some, a little bit....
Also --Contact these guys too for a quote. What used to be called "high tech" is more common now. https://www.alliedtitanium.com/prod...6&Search=Search&S_UCatalogue=74&S_UMaterial=1
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Prairie Schooner
Jeff & Donna, E35-3 purchased 7/21
Is that a crack going out from the top hole?!
EricHasAnEricson
Member II
Indeed, that crack is across the top hole. On one side it has completely separated, on the other side the crack is just beginning...
The crack was not there when i replaced the standing rigging and tightened it all down. Not visible to me at least.
I crossed the sea of Cortez as a "shakedown" two days ago. We had about 20 knots on a deep broad reach. The boat behaved excellently, but I believe this is what aggravated the weakened chainplate. I did manage to average 7.3 knots, pressing the boat a bit.
Today I took tension off the backstay by loosening the turnbuckle. I set up both running backstays (my addition) as a backup as well.
I'm going to order a chainplate from rigging only, they supplied my new standing rigging and have one that looks like a close enough fit. I don't trust that the stainless I'll get around here in Mexico will be proper 316.
For now, I'm planning to jury rig a few reinforcements and then motor the rest of the way to La Paz.
The crack was not there when i replaced the standing rigging and tightened it all down. Not visible to me at least.
I crossed the sea of Cortez as a "shakedown" two days ago. We had about 20 knots on a deep broad reach. The boat behaved excellently, but I believe this is what aggravated the weakened chainplate. I did manage to average 7.3 knots, pressing the boat a bit.
Today I took tension off the backstay by loosening the turnbuckle. I set up both running backstays (my addition) as a backup as well.
I'm going to order a chainplate from rigging only, they supplied my new standing rigging and have one that looks like a close enough fit. I don't trust that the stainless I'll get around here in Mexico will be proper 316.
For now, I'm planning to jury rig a few reinforcements and then motor the rest of the way to La Paz.
I took my cracked chainplate to a local welder. He copied it in 504. $100.
...
ericsonyachts.org
Chainplate Crack Cause, Effect, Theory, RFP
The backstay chainplate of the '84 Ericson 381 was cracked. Missed by surveyor, because when a boat's transom extends past the slip, it's impossible to see without a dinghy--and when hauled out, a ladder is required. This hefty piece of stainless is 2" x 13" and almost half an inch thick. I...
EricHasAnEricson
Member II
Thanks for sharing that thread Christian - a lot of good info in there.
I'm now thinking it makes more sense to get my chainplate cloned locally to ensure the holes line up. My original plan of backfilling the holes and drilling new ones is not sounding like such a great idea to me anymore.
I'm now thinking it makes more sense to get my chainplate cloned locally to ensure the holes line up. My original plan of backfilling the holes and drilling new ones is not sounding like such a great idea to me anymore.
AlaskanPuffin
Junior Member
Wow! It looks like you caught that crack just in time. After seeing both yours and Christian's crack in the same location, I'll be checking mine with dye penetrant, just to be sure. It would be quite a mess if that chain plate let go while sailing. What are the downsides to replacing it with a carbon fiber chain plate?
Stainless works and is proven and widely available. Carbon fiber is not proven, often laid up by hand, and I have broken an expensive carbon fiber whisker pole twice (its great quality is lightness, which is uneccessary in this applicaton.) I'm against titanium too, I see it as overkill.
That is one heck of a scary failure. It may result from the bend in the metal (such hardware is usually cold-bent by the fabricator), which might introduce unforeseen molecular issues. My crack was exacerbated by misalignment by the factory, I think.
But in the end, it's just a hunk of stainless that went bad over time, and personally I would replace it with a new hunk of stainless good for the next 40 years.
That is one heck of a scary failure. It may result from the bend in the metal (such hardware is usually cold-bent by the fabricator), which might introduce unforeseen molecular issues. My crack was exacerbated by misalignment by the factory, I think.
But in the end, it's just a hunk of stainless that went bad over time, and personally I would replace it with a new hunk of stainless good for the next 40 years.
AlaskanPuffin
Junior Member
That makes sense. The metal would probably get fatigued from 40 years of vibrations, no mater what. Maybe it is just something that should be changed out every few decades. Ti is even more brittle than stainless so it could potentially suffer from the same problems.
peaman
Sustaining Member
I took a close look at my backstay chainplate today and am happy to say that it looks fault-free. But I find it interesting that, of three different failed pieces described here, the failure occurred at either the top or next lower bolt hole. So it seems like those other four (4!) bolts may look like serious security, but they in fact do nothing useful. I don't know enough to be specific, but it seems like a design deficiency to me. If I had occasion to do anything with mine, I think I would drill out the holes through the transom for a close, unthreaded fit for the bolts so the tang and the backing plate could float a bit to spread the load through the whole piece.
AlaskanPuffin
Junior Member
That is a good idea to open up the bolt holes to spread the load. Another thought is to TIG weld a vertical piece of stainless to either side of the plate to stiffen it up.
Based on the observed increased thickness of our boat's transom center where the SS plate was attached, I really doubt that the plate was bending or vibrating. IF an owner were at all concerned and already had the SS plate off the boat, they could epoxy on a piece of 1/4" G10, set in thickened epoxy, on the inside. Re-drill the holes, and "Bob's your uncle"....
Applying the methodology to search first for the least complicated answer, I would guess that some SS parts like that had a microscopic flaw in the metal that took about 40 years to manifest and become visible.
(In one of my long ago college summer jobs I was a laborer at a plant that refined rare metals like zirconium, and cast rocket nozzles from it. They would use ultrasound to find small internal flaws that might cause a failure under use. These flaws were totally invisible on the surface of the part. Expensive, but these parts were said to be intended for use at NASA.)
Applying the methodology to search first for the least complicated answer, I would guess that some SS parts like that had a microscopic flaw in the metal that took about 40 years to manifest and become visible.
(In one of my long ago college summer jobs I was a laborer at a plant that refined rare metals like zirconium, and cast rocket nozzles from it. They would use ultrasound to find small internal flaws that might cause a failure under use. These flaws were totally invisible on the surface of the part. Expensive, but these parts were said to be intended for use at NASA.)
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EricHasAnEricson
Member II
Thanks everyone for your thoughts and ideas. Here are some better photos of the damage.
It appears to me that the design of this chainplate places bending stress at the first bolt hole. Certainly the damage seems to back up that claim.
I can get a replacement made up locally out of 316L for $300. Grade 5 titanium is $520. Another idea is to redesign the plate to remove those bending stresses.
My favorite of these options is the titanium route. That's a "forever" solution assuming the bending stresses are low enough to not fatigue the material.
Lead time for titanium is 60 days. So I'd be welding together a temporary reinforcement in the meantime. I'm going to take the chainplate off when I arrive in port today and inspect. If the whole underside is a mess of crevice corrosion, then I won't risk a temporary fix and just get it done right here right now.
It appears to me that the design of this chainplate places bending stress at the first bolt hole. Certainly the damage seems to back up that claim.
I can get a replacement made up locally out of 316L for $300. Grade 5 titanium is $520. Another idea is to redesign the plate to remove those bending stresses.
My favorite of these options is the titanium route. That's a "forever" solution assuming the bending stresses are low enough to not fatigue the material.
Lead time for titanium is 60 days. So I'd be welding together a temporary reinforcement in the meantime. I'm going to take the chainplate off when I arrive in port today and inspect. If the whole underside is a mess of crevice corrosion, then I won't risk a temporary fix and just get it done right here right now.
Looks like the top crack caused by misalignment of the chainplate, as in my case. See link in Post #6. .
I would lean towards having a new one made out of 316 SS by a local fabricator. Titanium would be ideal, but 38 years for a SS chainplate seems like a good run. Having a local fabricator would also allow you to make sure the angle is correct. On my boat, it looks like it's off by a few degrees.
AlaskanPuffin
Junior Member
Wow, that looks like it was just barely hanging on there. Glad it didn’t bust loose while you were sailing. My only thought is that the titanium could have the same problems as the stainless although it is a very strong and very corrosion resistant metal it is a very brittle metal and is prone to crack in high vibration areas. It might take 100 years for a big chunk of titanium to develop a crack so maybe it’s not a problem. Like Christian and Nick said, alignment with the angle of the backstay is very important. I think welding a 1" piece of stainless or titanium to either side down the length of the bracket to make it a "C" channel shape would make the piece much stiffer and more resistant to any bending forces caused by the vibrations in the rigging.
peaman
Sustaining Member
There is nothing preventing you from increasing the width of the piece, to put more beef beyond the bolt holes.
Along those same lines, the countersunk holes likely remove a lot more material than is really necessary. Pan-head screws wouldn't likely protrude enough to cause any problems, and they'd allow less drilling in the chainplate.
I think the most important thing, when reinstalling, is to insert the lowest bolt first, then tension the backstay. Or maybe the top bolt first, not sure it matters.
The chainplate has to line up naturally before holes are drilled, and I think Ericson was casual about that in my case. If slightly askew when bolted down the strain isn't even on the steel.
The chainplate has to line up naturally before holes are drilled, and I think Ericson was casual about that in my case. If slightly askew when bolted down the strain isn't even on the steel.