Fiberglass Separating at Chainplate

[nelly]

Hi all,

Wasn't sure if I should post this here or in the maintenance forum. Looking for opinions.

See image here: https://i.imgur.com/i5saO6W.jpg

This is the port aft lower shroud on my 37' cutter.

You can see here what looks like fiberglass tabbing is pulling up. Nothing noticeable moving under sail (was out just yesterday in 15-20 knots with plenty of sail up) - but the single chainplate has moved up (looks like anyway) probably about 1/32" above the deck - I can tell because there is some sealant etc. just barely visible.

There is also some separation of the wood shelving on the outside of the feature here of the boat that caused me to inspect this area. It has been like this since last season.

There isn't anything noticeable yet on the upper shroud area - both port and starboard have been inspected and look okay other than this one shroud.

What I'd like some second opinions on:

1) Is this very serious? (my guess is no - maybe sail her a little easier for a while but fix it over the winter).

2) Also how would you go about repairing?

3) Any other thoughts?

I will inspect the deck core for softness. There is one area not anywhere near the shrouds that may have some softness issues, but I will make sure I check around the chainplates.

Thanks for reading!

[Sailmonkey]

Can you post a few more photos? Not as zoomed in. I’m not able to tell if the knee has moved up, the shelf has moved down, or even how anything is constructed.

[nelly]

Originally Posted by Sailmonkey

Can you post a few more photos? Not as zoomed in. I’m not able to tell if the knee has moved up, the shelf has moved down, or even how anything is constructed.

I can take some more. It is honestly hard to tell, but if I had to guess the knee moved up.

[Sailmonkey]

Has the knee separated from the hull at all? The cabinetry shouldn’t be supporting it at all, rather the other way around.

[nelly]

Originally Posted by Sailmonkey

Has the knee separated from the hull at all? The cabinetry shouldn’t be supporting it at all, rather the other way around.

No, it has not. I'll triple check in a day or two when I'm back at the boat, but I'm 99% confident there is absolutely no visible cracking at all where the knees (both port and starboard) meet the hull.

[tkeithlu]

I've hesitated to post thoughts, because I agree with Sailmonkey.

Some thoughts on seriousness: Any difference in this crack on a port versus a starboard tack, such that the shroud is loaded/unloaded? Tension OK in the other shrouds? Bolts tight? No sign of pulling at the bolt heads (evident none at the nuts from the photo). Where does this crack go? Have you probed it with a wire? Odd that it would be on the inside of the hull but not evident elsewhere, or is it?

What I really can't see is whether this crack is from the stress on the shroud or your having sat on the shelf. You say the chainplate has lifted at the deck (1/32"), but neither the chainplate nor the bolts appear to have been dislodged. Is that sloppy paint cracked?

Repair: If this is a structural failure (not just the shelf), then either lay up more fiberglass or install a larger chainplate that distributes the load more widely in the hull. Filling the crack won't add much strength. Laying up fiberglass means removing paint first so you can make a bond. Nasty job, but doable.

[a64pilot]

You can apply a bead of what is called anti sabotage lacquer. A thin bead about toothpaste consistency that quickly dries hard and breaks easily, go for a sail and if it doesn’t break, there is no movement going on.
I suspect the bulkhead the chainplate is bolted to has broken loose not the chainplate.

[nelly]

I agree there isn't movement of the chainplate itself, but if anything the bulkhead or what is referred to as a knee.

Actually I'm now not convinced it moved at all since I'm very confident there isn't any cracking where the knee meets the hull, but I will confirm this.

This image might do more harm than good but here you go. This picture is many years old (prior to me owning the boat) but you can see the damage doesn't exist here: https://i.imgur.com/zCY1J9b.png

Where the blue line is is the edge of the knee: in my first photo it would be on the left side of the image. So the chainplates edge-to-edge are port to starboard. Meaning, the bolts face fore and aft.

Where the orange circle is is where the base of the shelf meets a piece of wood. There is actually a gap here: about 1/4" or more - meaning much more than the crack.

There isn't any support under this shelf running the length of that birth. So you have 5-6' of shelf and the only supports are on top of the shelf, being the knees.

I've never sat on the shelf (not really possible) but absolutely have leaned on it, grabbed it, and have had plenty of heavy things stored there - cases of beer, etc..

Some answers:

> Any difference in this crack on a port versus a starboard tack, such that the shroud is loaded/unloaded?

I didn't notice anything!

> Tension OK in the other shrouds?

Yes. Actually they are roughly same tension as when I tuned the rig, checked by loose gauge.

> Bolts tight? No sign of pulling at the bolt heads (evident none at the nuts from the photo).

I actually did not check this. I will do so. I just rebedded these 2 seasons ago but the bolts all look fine. They are new bolts.

> Where does this crack go? Have you probed it with a wire? Odd that it would be on the inside of the hull but not evident elsewhere, or is it?

Unsure where it goes - have not probed it! Good ideas and I will do so soon. Only other evidence is on the shelf wood is pulling itself apart. I will take more photos of this when I get to the boat.

> You can apply a bead of what is called anti sabotage lacquer. A thin bead about toothpaste consistency that quickly dries hard and breaks easily, go for a sail and if it doesn’t break, there is no movement going on.

This is a great idea! I had my finger against it and didn't feel movement while sailing - but who knows. I will buy some and give this a shot.

[Slainte1]

It is impossible to be certain from the photo but it looks to me as though tension on the shroud has caused the crack. Is the knee? glassed to the stringer below, it doesn't look like it. what is the knee bonded to? Photo from further away and any from further to the right would help visualise the problem. maybe a sketch?

[tkeithlu]

A64Pilot, where do you get that stuff? I wondered when I was thinking about the original poster if there was something brittle that would do that job.

[Sailmonkey]

Originally Posted by tkeithlu

A64Pilot, where do you get that stuff? I wondered when I was thinking about the original poster if there was something brittle that would do that job.

Here’s a blevy of links to purchase


https://www.google.com/search?q=sabo...&client=safari

[Scaramanga F25]

Is that a shelf or a F-G pan or liner, Need a pic from a distance.

[nelly]

Originally Posted by Scaramanga F25

Is that a shelf or a F-G pan or liner, Need a pic from a distance.

It is a shelf, see here: https://i.imgur.com/zCY1J9b.png this is the port side where I have these lines drawn (see my reply above regarding these lines).

The blue line is where the kneel that has the separation is located.

I will try and get better pictures tomorrow

[Cliffhanger]

I would check the rest of the bulkhead/hull joint for any signs of cracking if you can. That bulkhead should extend all the way behind the seats down to where the hull curves in. It might not be easy to see and there might be all sorts of things in the way. If there is no cracking there then it would suggest that things are structurally OK.

In this case it can only be the shelf breaking away from the bulkhead which is trivial. The fact that there is no signs of cracking where the bulkhead meets the hull (on the right hand side of the photo) is encouraging. Any movement of the chainplate should result in cracking here. Also, if you think about it, if there was any movement of the chainplate/bulkhead upwards it would probably have just lifted the shelf with it. I can't quite see it from the photo but is there a separation between the inside edge of the shelf and the varnished timber strip? If so, this would indicate that the shelf has dropped.

If so, you should reinforce the shelf or drink less beer!

[nelly]

Originally Posted by Cliffhanger

I would check the rest of the bulkhead/hull joint for any signs of cracking if you can. That bulkhead should extend all the way behind the seats down to where the hull curves in. It might not be easy to see and there might be all sorts of things in the way. If there is no cracking there then it would suggest that things are structurally OK.

In this case it can only be the shelf breaking away from the bulkhead which is trivial. The fact that there is no signs of cracking where the bulkhead meets the hull (on the right hand side of the photo) is encouraging. Any movement of the chainplate should result in cracking here. Also, if you think about it, if there was any movement of the chainplate/bulkhead upwards it would probably have just lifted the shelf with it. I can't quite see it from the photo but is there a separation between the inside edge of the shelf and the varnished timber strip? If so, this would indicate that the shelf has dropped.

If so, you should reinforce the shelf or drink less beer!

Haha! Already trying to cut down on the beer. Trying!

I'll double check everything you mentioned. So the bulkhead does NOT extend all the way behind the storage compartments. Maybe an odd design, but there's just hull back there. It's the same on the starboard, but I'll check and make sure it doesn't look like anything was cut out to make extra space there (I'm confident it wasn't but I'll absolutely check). The starboard side is a fold-out berth to make an extra-wide bed area, and the cushion that is directly against the hull there is almost certainly original to the boat.

The knee/bulkhead/whatever-we're-calling-it! only extends to the TOP of the "shelf" area. It doesn't even go below the shelving. It is tabbed to the hull however.

This is true for the upper shrouds as well! Actually the lower forward shrouds ARE the midship bulkhead (you'd think this would be the uppers? but no!) so those are extremely solid. But the aft lowers and upper shrouds are just these knees.

18k pound 37' cutter rig for what it is worth.

It wouldn't be the first time some non-structural component on this 1980 boat has separated a bit and needed some love.