Inspection of Encapsulated Chainplates??

[jimp1234]

Several older cruising boat I've looked at have encapsulated or embedded chainplates. These are often inboard, not visible below deck because of wood cabinets in the saloon, and show no issues at deck level (where the tang of the chainplate comes through the deck). Is there any way to inspect these chainplates along with the chainplate knee below deck? I guess you'd need to drill a small hole through cabinets in the saloon on some boats and run a fiber optic camera? But of course if the knee is fully encapsulated in fiberglass you might not be able to see much of the chainplate anyway. Or if the boat is old enough do you just assume you need to rip our the chainplates and install new? Anyone have this done or find a boat yard that does this? Any info on this topic would be appreciated.

-Jim

[Cheechako]

It's a tough one for sure. Especially if they are encapsulated. Drilling a small hole at the bottom of the encapsulation might let you know if it's wet in there. Other than that you are relying that the owner(s) having kept the sealant in good condition at deck level.

[Boatguy30]

I believe it's possible to check with an ultrasound system.

At least this works to find fractures in carbon masts after lightening strikes. I would imagine would work. Of course you won't see crevice corroded areas likely to crack, just existing cracks

[a64pilot]

Like rigging, they need to be replaced at an interval, 15 yrs is almost certainly safe, beyond that?

[picklesandjesse]

I had a Frers F and C 44 about 20 years ago and it had these type of chainplates. The boat was about 20 years old and had not been maintained correctly. If you looked carefully when the sun was at the right angle you could see bumps where the chainplates were. This indicated where there was a problem. Many F and C's have had there chainplates redone but it's a big job. The best time to look for the bumps is close to sundown when the boat swings or you can use a flashlight at night at a very narrow angle.

[Boatguy30]

Laminates contract slightly as they cure. The stainless chainplate doesn't so a hard spot is left that's noticeable on the fair hull.

This doesn't indicate a problem with the chainplate, just location.

[leftbrainstuff]

Very difficult to inspect. XRay will give a better image than ultrasound depending on operator skill and scanning technique.

The chain plates on our 33 year old Liberty 458 have very slight crevice corrosion at the interface where they exit. I removed the cover plates and was able to inspect a max of 4 inches down. If you're optimistic you could claim a 20% of encapsulated chain plates was inspected. This is not enough to have confidence.

I've evaluated composite, titanium, bronze and stainless replacements. I have extensive fabrication and engineering experience with all these options.

At the moment I'm leaning toward embedding titanium tophats that sandwich the existing chain plates. Then adding external and removable stainless chain plates.

I"m also considering spreading the standing rigging loads for and aft of each current chain plates. The encapsulated chain plates design is not an elegant engineering solution.

The nine of cups Liberty 458 replaced their chain ppl plates in South Africa. Another Liberty 458, from the Yukon, also replace theirs during a major refit. I'm not aware of any chain plates failures in the Liberty 458 and many have circumnavigated.

[roverhi]

Most chainplate failure is in the area where the chainplate passes through the deck. Salt water can/will infiltrate and in an absence of O2 cause crevice corrosion. When you encapsulate a SS chainplate you are making the whole buried chainplate subject to crevice corrosion. It's usually relatively easy to inspect non encapsulated chain plates by pulling them and replacing any that are bad though I'd just replace them all. With embedded chain plates you are looking at a very messy and labor intensive job just to look at them and more money to replace. I wouldn't buy a boat with embedded chain plates unless they were relatively easy to replace or I got the owner to do it before closing on the sale.

[Dougtiff]

Well it's a bitch to access glassed in chain plates for sure, have done it on a couple of CT 41'S and sea Wolfs [Taiwan built], used the original plates as backing and installed new ones on the outside of the hull, one could cap off the original plates, install the new ones next to the original, say a inch difference will not make any difference.

[Seadoc777]

Aare I have a CT41 1977. Thinking of installing external Chainplates using the existing plates by passing the securing bolts through the internal plates. It should be straight forward once the internal plates are exposed. Any obvious problems?

[Cheechako]

Originally Posted by Seadoc777

Aare I have a CT41 1977. Thinking of installing external Chainplates using the existing plates by passing the securing bolts through the internal plates. It should be straight forward once the internal plates are exposed. Any obvious problems?

The most difficult issue will be drilling thru the old plates. You need the right drill, the right rpm and a good touch. I would open up the bottom of the glassed in plate to allow any moisture to exit.

[callistov42]

I had a chain plate failure (encapsulated chain plates) on my Vagabond 42. We had pulled four (of the 12) and had them X-rayed by a facility that inspects turbine fan blades. They were determined to be OK. Then, 6 years later one we didn't pull failed and I ended up having to have all 12 replaced. Big job. $30,000. You really can not inspect them in place. If the boat is more than 20 years old, you should be suspect. Watching the seal at the deck and all that helps, but eventually, life in salt water will get them.

[billgewater]

Very topical.
A day or so ago, a local marine dealer was discussing this very issue. He related the story of a yacht where the entire rig collapsed due to corrosion failure of embedded chain plates. Apparently due to weld failure. However the really bad news was that the insurance company refused to cough up a cent. A local rigger confirmed the story. I think if I had embedded plates I would be checking with my insurance company. The cost, if not impossibility, of surveying such fittings seems to be an area of considerable concern.
It also seems that a design philosophy is at play here. You would like to think that crucial components in a yacht should be fitted in such a way that inspection and removal of critical components is easy to achieve. Convenience and a flash looking product may help sales but surely the industry should meet high if not regulated safety and build conditions.
When your lap top dies, provided you have done back ups, the emotional depression resulting from failed irreparable technology is minimal. Not so with the family boat. You can't just toss the boat in the recycle bin. You may have seen some really gorgeous very old boats that clearly have been loved and survived simply because they could be maintained. Not sure about many modern boats.

[TheThunderbird]

I inspected and checked all nuts and bolts connecting chainplates to structure.

Those stupids had used (easy!) threaded bars for bolts, thus allowing crevice corrosion. I could snap off M12 nuts manually..

I got so crazy that l suspended the last 20%payment to PO....

I replaced with lathed bars with no threads where they are supposed to work.

[Boatguy30]

Generally the problem is the chainplate itself either near where passed thru the deck or on the unseen side against bulkhead or hull. Simply replacing a few bolts isn't really that productive.