Crack in deck?

[Bigjim]

This fall I noticed a crack forming by one of my chain plates. Besides patching the crack, what else should I be looking for during this repair?

The deck has some vertical deflection around the location of this crack compared to the one on the opposite side of the boat.

The boat is 41 years old. All the other chain plates look normal.

[Bigjim]

I have not checked whether this crack goes all the way through the fiberglass.

[psk125]

Before I fixed the crack I’d want to know what was causing it. It looks like there might be a bulkhead beneath it? What’s making the deck flex (and therefore crack) there? Is the shroud trying to pull the bulkhead up through the deck? Something is going on and needs to be checked out.

[billknny]

A lot depends on how your boat was built.

If that crack goes through the upper layer of laminate over a core, you could have a seriously wet core. If core is exposed at the chainplate penetration through the deck, water intrusion could be the source of your problem.

If that area is solid fiberglass, and that is a structural crack (it looks like more than just gelcoat crazing) then serious forces are at work here that shouldn't be. The chainplate should not put any force upward on the deck. It should be attached to the hull or a structural bulkhead inside.

[Bigjim]

I definitely think there is water intrusion. The boat has several long time leaks before I bought her. I have been sealing them up one by one. The plates above the chain plates had old crusty sealant. I replaced it with new butyl rubber.

My first chore is to grind away the surface and see how deep it goes. There is wood in various areas but not everywhere. One spot had a hole cut in it for a pump out fitting but they sealed it up badly and put the fitting in about a foot to one side. I don't remember whether there was a wooden core there.

[coopec43]

Can you tell us the design of the boat?

You say "crack forming by one of my chain plates" but where?

How the chain plate is anchored.

Is the deck cored or solid?

Thanks

[gmakhs]

Don't focus on the crack focus underneath, something is wrong with the chain plate anchor system and the mast pulls the deck up.

[Bigjim]

The boat is a Columbia 10.7. The deck probably has plywood core. That’s what I’ve found elsewhere.

[SwellGuy]

Show us a picture of that chainplate from the inside of the boat.

[Bigjim]

I will post photos of the inside as soon as I can get them.

[coopec43]

This is the layout of the Columbia 10.7

[Hardhead]

I'm certainly no expert, but I'd check the entirety of whatever structural bulkhead the chainplate is mounted to, underneath. It seems something must be giving way to a degree, and/or there is a deck core issue. When you get to the boat next, I'd bring something to seal that crack just temporarily, until you can find what's really going on. Good luck - this is why we love our boats...

[Bigjim]

We found the issue and the solution. It is detailed on this thread

https://www.cruisersforum.com/forums...84#post3165584