Chainplate popped out when sailing - what's next?

[phorvati]

Consider yourself very lucky you are not sourcing a new mast. Old columbia, what do you expect. You can usually see the early signs, like deck lifting, rot, cracking in gelcoat, soft deck. Get a moisture meter and learn how to use it and how to interpret results.

The worst is when they glass-in those chainplates into a bulkhead or a hull and build up nice teak interior like cabinets etc, right over them, like on more expensive boats. Then it takes several days just to get at the problem. So another plus is you don't have to deal with tearing down a nav station or a settee to get at it.

[stormalong]

At 52 years it is time to replace them all. Stainless steel crevasse corrodes and you can barely see the corrosion because it is perpendicular to the surface. Being wet with salt water and oxygen deprived is the formula for crevasse corrosion. Replace them with 316 stainless.

Glassing them in creates a pocket for water accumulation and makes them impossible to inspect. Bolting is much better and easier to service. Before through bolting reinforce the hull in that area by building up layers of alternating layers of fiberglass mat and cloth. Study up on the proper way to fiberglass.

[sailcrazy]

A friend of ours had a 52'motorsailor, with chainplates glassed to the hull. Unfortunately, stress cracked the f/g, a little water got in, and crevasse corrosion set in-but could not be seen! The chainplate separated, and he lost the mast 50nm off shore! He got back, safely, and ended up redoing all his chainplates. As has been suggested, he redid them all to external chainplates, thrubolted thru the s/s/chainplate, the hull, and to f/ged in-place reinforced pads. Although external chainplates ARE subject to getting water between the chainplate and the hull (and the resulting corrosion), at least you can see it. He polished the s/s, and the end job looked really good! Just know you need to pay attention to crevice corrosion behind the chainplate .

[ArmyDaveNY]

Be sure to have your chain plates checked as others have mentioned. If they are questionable or worse, you may wish to have titanium replacements made. There are significant advantages to titanium and they are not necessarily terribly expensive. There was lad who had a thread about how he makes these and how he'll make them for you. Bronze is another good choice and may be less expensive. Good luck with them.

[heron237]

If your chain plates are attached to the inside of the hull wouldn't there be a force trying to pull them toward the center of boat i.e. the mast? A direction that would be trying to pull them OUT, If I had my way... and the adjacent bulkhead was beefy enough I'd attach the plates to it......

[Scaramanga F25]

S.S.Chainplates should never be covered/buried with/under fiberglass. This old method has proven to be bad. Low oxygen corrosion.
As mentioned above.

[Jim Cate]

Originally Posted by Scaramanga F25

S.S.Chainplates should never be covered/buried with/under fiberglass. This old method has proven to be bad. Low oxygen corrosion.
As mentioned above.

Hmm... Let's see, the subject chainplate served for over 50 years, and when it failed, it was not the stainless that failed but rather t he glassing that held it to the hull.

Your statement, whilst theoretically supported seems out of place in this discussion.

Jim

[jmschmidt]

Ah, rig comes down?

[BillinKL]

Originally Posted by Cheechako

I believe that chainplate was intended to be attached more to the hull sides than the deck. (?) Based on the T bottom. So... the deck may not actually be your biggest problem. Rather, the old fiberglass that attaches the T shaped plate to the hull has given out. I would remove all chainplates including the stern, inspect the SS plates, Grind to fresh glass and re glass them to the hull.
Or make new chainplates and devise bolting them through the hull.

It may be worth considering increasing the size of the plates. They would have been sized to withstand the shearing of the bond between the plate and the hull. Since that bond has come away, the plate has simply punched through the deck.

[roverhi]

Originally Posted by Jim Cate

Hmm... Let's see, the subject chainplate served for over 50 years, and when it failed, it was not the stainless that failed but rather t he glassing that held it to the hull.

Your statement, whilst theoretically supported seems out of place in this discussion.

Jim

Laminated in SS chain plates are notorious for developing crevice corrosion and failing. If you can keep salt water out, no problem. Anyone guarantee that anything that is subject to loading so it will move and won't breakdown the seal. Doesn't happen to all boats but unfortunately the way most people find out is when the chain plate fails and the mast is flapping in the wind. With laminated chain plates, the only way to find out the condition of the chainplates is to remove them which is a major PITA.

Just because your chain plates aren't laminated in doesn't mean you are home free. Where the chain plates pass through the deck Is a typical leak problem and cause of chain plate failure. Even exterior chain plates can have problems. The big plus for bolted on chain plates is you can easily pill them and inspect. Did that on my 50 year old plates and only found a couple with corrosion. Fortunately the corrosion was bad enough to cause a failure.

For me, laminated in chain plates are a non starter. If the chain plates can't be easily inspected, you are living on borrowed time and the mortgage can be called at any time.

[Fore and Aft]

My chainplates pass through the deck and I am paranoid about leaks. So I masked up the deck and chain plate and put a nice big Sikaflex cove on each chain plate. When that Sikaflex finally fails it is no big job to replace. The best bit is that it’s an easy visual check to see if the Sikaflex has failed.
The bottom piece of the T chainplates needs to have the four corners radiused as well. A radius around the size of a 50 cent coin would work, it just makes it easier when laying the glass on top. Another poster mentioned laying some glass on the underside of the deck and that is a good idea. I would be aiming for 50mm, then 100mm and finally 150mm wide layers of glass on the underside of the deck. By that I mean the glass cloth on the chain plate then follows up and under the deck all in one piece. The 150mm lap will be awkward but achievable.
I am not sure what “borrowed time” is but if you have not changed your chainplates in 50 years I think you have to expect some issues.
Cheers

[cal40john]

Originally Posted by heron237

If your chain plates are attached to the inside of the hull wouldn't there be a force trying to pull them toward the center of boat i.e. the mast? A direction that would be trying to pull them OUT, If I had my way... and the adjacent bulkhead was beefy enough I'd attach the plates to it......

You need to know how the boat was designed before making changes.
In this case the load is taken to the hull. It's an upper so it's pulling straight up, but pulling straight up could result in the hull trying to bend inward. That is why they put a bulkhead where they did right next to the chainplate.

If you put the chainplate on the bulkhead, and the bulkhead isn't well fastened to the hull, then the deck takes the load. Was the boat designed to take the load on the deck?

The Cals I'm familiar with have the chainplate on the bulkhead and the bottom of the bulkhead bolted to an athwartship steel beam that goes under the mast so the tension forces are resolved in those structures. The bulkhead is fastened to the hull, tabbed in all along the hull.

Catalina 27s baffle me a bit. The bulkhead is fitted into a slot in the liner, not fastened to the hull and the chainplate is fastened to the the upper bulkhead. So the deck must be designed to take the load and be attached to the hull well enough.

The 3 or 4 #10 screws tying the upper bulkhead to the glassed in under settee bulkhead look owner installed and inadequate to the task of taking the load to the hull on the boats I've seen.

[Visarend]

"I believe that chainplate was intended to be attached more to the hull sides than the deck. (?) Based on the T bottom. So... the deck may not actually be your biggest problem. Rather, the old fiberglass that attaches the T shaped plate to the hull has given out. I would remove all chainplates including the stern, inspect the SS plates, Grind to fresh glass and re glass them to the hull.
Or make new chainplates and devise bolting them through the hull."

Cheekchako has it right: this is the very reason why I built Osprey with chainplates bolted through the hull:
https://www.facebook.com/ospreysaili...dmin_todo_tour

[gjordan]

I may be wrong but I believe the Columbia 38 was built similar to the early Columbia 40s that had a steel cage built into the hull that ran from one side of the boat to the other to have all strains taken by the cage/straps that ran under the mast step and up both sides. This was mild steel and some of them have completely rusted out. I was interested in a Columbia 40 (centerboard boat) and a friend told me to research it, and that info came up. I think the 38 is the same. If that is the case, the hull and deck are designed to be supported by the cage and on their own , may not be strong enough. Since the chainplate that pulled didnt look like it was bolted to something at its lowest point, it may have been replaced once before. I found the cage issue and drawings on the internet, so the info is out there. It is worth some research. _____Grant.

[skenn_ie]

The plate looks very light and short, to me. If bolted to the hull, at least 4 bolts, and reinforcing on the opposite side of the skin. I would favour attachment to a frame or bulkhead, aligned with the tension. GRP doesn't take point loads like bolts, very well. Having had some to do with homebuilt aircraft, attachment points had either wood or metal, embedded in the glass, then extra glass. Critical bits like wings, had 3 ally plates sandwiching the glass.

You were lucky that you didn't lose or break the mast.