Chainplate Failure and Concerns

[barnakiel]

For sale: 5200 (female) chest implants ... guaranteed to stay put.

Or only a cruiser's reverie?

;-)
b.

[zeehag]

Originally Posted by barnakiel

For sale: 5200 (female) chest implants ... guaranteed to stay put.

Or only a cruiser's reverie?

;-)
b.

ROFL!!!!!!!!

[First Mate]

we spent the last couple of days talking to a rigger in Port Townsend.

What I gleaned from his knowledge on chain plates:

The cracks start on the inside of the metal and work their way to the outside. By the time pits and cracks show up on the outside where they can be seen, the interior matrix of the plate or bolt or turnbuckle is really in bad shape.
Lack of oxygen coupled with water exposure make stainless steel corrode; hence, where the plates penetrate the deck, the above mentioned cracks and pits will be found but the exposed areas will be bright and beautiful. The moral is that proper inspection means removing chain plates and bolts from their covered locations and exposing them to visual inspection.
Stainless steel means it stains less but it still stains.
The cyclic loading on the plates could eventually wear them out, but the corrosion always get the plates first.
Same issues that apply to the plates apply to the bolts that connect the plates to the hulls.
If a plate is not exactly loaded on its centerline, one side gets more stress than the other and that can cause it to over stress and crack. This is of particular importance with the less Hercie (as in Herculean) plates at the top of the shrouds where the shrouds attach to the mast, not just to the beefy chain plates.

He showed me a few boxes of chain plates, bolts, turnbuckles, etc that are severely damaged in interesting and attention grabbing ways. He saves these items to show clients and educate them.

Best to err on the side of caution. Talk about a failure that has little running time as we call it in engineering - you want to have time to run away! when the item fails. Failing rigging is spectacular I understand.

[Stillraining]

Its going to be a huge job on my boat ..I'm not looking forward to it at all...nor am I going to be doing it any time soon...I'm going sailing or I'm going to die trying I could care less at this point....All passengers beware..you have been notified...

[First Mate]

Originally Posted by Stillraining

Its going to be a huge job on my boat ..I'm not looking forward to it at all...nor am I going to be doing it any time soon...I'm going sailing or I'm going to die trying I could care less at this point....All passengers beware..you have been notified...

doing ours in December when the boat is on the hard and it's too cold for our silly behinds to be out in the weather or on the water.

not looking forward to it either. thankless task!

[sigmasailor]

Originally Posted by dadidoc

Recently found a crack in my chainplate for the aft main stay on my Morgan 416. Had two new ones made up and installed each. Opposite side was OK. I inspected all others and then went up the mast and looked at all the rigging hardware and took high definition pictures.

Some think I should pull every chainplate and this would pretty much end the season. I inspected every one and found no visible cracking like the one I found. Take a look at my link and the pix I included.

What say you ? Any expert advice or advice with experience would be appreciated. thank youMain Starboard Intermediate and Upper

If you have cracks starting they will not be visible with the human eye. The suggestion to X-ray solid metal objects is not so useful. X-ray will just show volumetric faults; cracks hardly have any volume so the chances of finding them using X-ray are very slim.
The best (and easy) way is DPI (Dye Penetrant Inspection); this will show hairline cracks at the surface if they are there. If you want to be really safe you have to disassemble the lot since any cracking will usually start at the side you cannot see (between plates and boat).
Good luck.

Eric

[zeehag]

my cracks are plain and with good cause-- the previous owner nor rigger placed any blocks between hull and chainplate and the torquing of the ketch rig cracked em while sailing from san francisco a few years ago. so i can see my cracks. not all cracks are so small as to be unseen.

[sigmasailor]

Just do not make the mistake to assume that if you cannot see any cracks they are not there. Stainless steel is a wonderful material but when deprived of free air flow (lack of oxygen and chloride built up) can do strange and very unexpected (A2 or 304 especially) things.

[silverp40]

Just a tip on the bedding compound: B5200 is really an adhesive as stated before by others and does not fare well over time when exposed to sunlight/heat. Hence, the edges of the bedding around the chainplates will quickly start to deteriorate and allow moisture in behind them.

Silicone is very resistant to UV rays but has poor adhesive qualities, especially behind a chainplate where there is a little movement.

So, why not use a sealant that has silicone and the great adhesive properties of polyurethane?

Enter Lifeseal (not Lifecaulk) from BoatLife. Excellent UV/heat resistance as well as adhesio. It's the best of both worlds -polyurethane and silicone.

[osirissail]

Originally Posted by Stillraining

Its going to be a huge job on my boat ..I'm not looking forward to it at all...nor am I going to be doing it any time soon...I'm going sailing or I'm going to die trying I could care less at this point....All passengers beware..you have been notified...

Welcome to the wonderful, idyllic world of cruising where you sail from repair to repair. And if a minimalist "gyspy" sailor your journey ends with the loss of the rig, et. al.
- - Then again, one of the main attractions of cruising is that you get to make the decision about whether something is worth life or death. Most bureaucrats can't swim so generally you are safe from their "requiring" you to have/do/fix this or that.

[seandepagnier]

I ordered aluminum bronze bar from mcmaster.. drilling it was a pain, but now they are on, and look cool, they are bright gold! I made them twice as thick and a little wider than the stainless I replaced.. The stainless I took off looked ok, but the chainplates had bends in them that they probably didn't need, and a little rust.

The cool thing is, the bronze will not have the kind of problem stainless does with stress corrosion cracking, this stuff is much more corrosion resistant than even normal bronze...

[pressuredrop]

gecko got any pictures? what did the project end up costing?

[silverp40]

Do they still make aluminum bronze?? We have 30 year old alum bronze cleats on our boat that are in great shape....almost like Marinium if anyone remembers those

Sounds like the strength tolerances have been accounted for by more than doubling the volume of the metal!!

[Zoomer]

While preparing my 30 year old Morgan OI for cruising, I noticed a small crack (damaged by P.O.) on one of my chain plates. After a lot of effort, I finally found a shop that would make me one, the result was poor but workable. A couple of years later, I found a small crack in another one (both were at bolt holes). Same deal, first shop out of business, finally found someone to make me one, another poor but workable replacement. If I could have found good set, I would have replaced them all.

As the chain plates are outboard, I ASSUMED that as long as they looked ok, they would do. Several years later while sailing in Venezuela, I lost the mast due to a chain plate failure on the port cap shroud. I had, as was my habit, just hand polished and inspected all of the chain plates.

The point of failure was where the plate "curved" over the side of the boat (not at the bolt holes). I believe it was "cyclic loading" as the break was fairly straight (the backside was exposed and no cracks were evident before the incident). Calder says ten years is all you can count on, I believe him.

The bad news is that I was stiffed by my "Jackoff" Insurance. The golden boy said it was "gradual deterioration" and therefore not covered (BTW, if a failure is caused by something new it will be "manufactures defect", also not covered).

Anyhow, I fixed it my self, for less than the deductible (lost 2.75").

Raphael, in PLC Ven., made me an excellent full set of chain plates and three years later of full time trade-wind cruising- no problem.

Now if I could just get back the money I wasted on "insurance"!
Pics and more:
Captain's Corner - Mast Rebuild

[smurphny]

I changed my shroud chainplates last year and increased their dimensions. Glassed over the pesky, leaky deck holes and moved 'em outside. When doing this it became apparent that a problem would be the increased distance from the hull where the last contact to plate is made, to the top of the plate. It's about 3". It's necessarily longer than the distance (about 1 1/2") of that little glassed-in stub coming up through a deck. Therefore, it is important to back up the exterior plates at the rail level to minimize flexure. With a couple of small blocks of teak epoxied to the toerail, any flex can be largely eliminated. This may seem like an insignificant thing but repeated flexing over time is a sneaky enemy.