Core rot under cleat

Apr 11, 2017
571
Catalina C22 Solomon's Island, MD
While poking around in the boat today, I found some plywood core rot under the starboard stern cleat. Evidently, water was coming in through the cleat bolt holes. I've cut out the inner lamination, and scraped away 2-3 layers of rotted plywood laminate layers. The wood above that, up to the underside of the decking, appears solid. The total depth of lost wood/inner fiberglass laminate is a little under 1/4". The cleat still appears very solid, and the fiberglass layup under the cleat must be fairly substantial. The rot goes from the stern cleat, forward, up to about 1/2" shy of the starboard stern pulpit post, which appears still solid, but very close to the edge of the rot.


The amber colored extrusions in the photos are some type of epoxy, added by the previous owner to fill some old through holes.

I was thinking of smearing some silica thickened 5 to 1 epoxy into the void caused by the 2-3 layers of plywood laminate that rotted out. From there, layering on a number of layers of 12 oz. biaxial fiberglass cloth, and extending the cloth over to the side of the hull on the outboard side, and around the inside of the combing on the inboard side. I'm new to fiberglass work, and not sure of the best weight of fiberglass cloth to use, or if this is the best method of repair. Given how shallow the damage is, it would seem difficult to insert a 3/16"" core replacement of the plywood itself.

After finishing the fiberglass repair, I was going to add a G10 backing plate for the cleat, and another for the stern pulpit post bolt holes. Does anyone have any comments? I'm open to criticism-
 
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Nov 6, 2006
9,885
Hunter 34 Mandeville Louisiana
Check out Maine Sail's excellent "How To" articles on the job you are facing.., sealing penetrations and rebidding deck hardware.. Get some of his butyl tape and if ya like what you see in the site, hit the "Donate" button so that Maine keeps adding to the site.. outstanding info!..
https://marinehowto.com/category/hardware/
 
Apr 11, 2017
571
Catalina C22 Solomon's Island, MD
That's a great website. I actually bought butyl tape from the same site last year. Good advice on sealing hardware.

Any advice on what weight/type cloth might be best?
 
Sep 30, 2013
3,538
1988 Catalina 22 North Florida
Nothing sucks worse than working with fiberglass overhead. So the way I see it, the thicker the cloth, the less layers, the shorter the job. Your plan sounds good to me, I'm just glad I'm not the one doing the work.

Maybe you could cheat a little, by substantially overfilling the void with thickened epoxy, smear the entire area with it, and then immediately slap on big thick piece of G10. The biggest that would fit, pre-cut to the proper shape. Thus skipping the cloth altogether?

Just thinking out loud here.
 
Apr 11, 2017
571
Catalina C22 Solomon's Island, MD
That's a good idea Gene. What has amazed me is how solid the cleat, and the deck above, feels. It's hard to get your eye that close to the area, but looking at the photos afterward, it looks like the plywood was only 1/4" thick to begin with. The layer of plywood I got to after cleaning out the rot is solid, and looking closely at the photos, it looks like it is just a single plywood laminate thick - the bottom fiberglass laminate is showing through in the cleat bolt photo. The fiberglass deck itself must be a substantial layup.

I was hoping it would not be a big job, but then again every project I tackle usually winds up taking about 3 times longer than expected. I'm not sure if cold beer has anything to do with it... or just the tricks of fate.
 
Nov 6, 2006
9,885
Hunter 34 Mandeville Louisiana
I agree with Gene on this one.. The rot does not look bad.. pull the cleat and seal per Maine Sail.. slather the inside with epoxy, apply a big backing plate of G-10.. snug it all up and go sailing.. The cleat loads on a C-22 aren't going to get big enough to defeat that fix.. just make sure it is sealed.. so it doesn't really rot.. Good luck with it..
 
Sep 30, 2013
3,538
1988 Catalina 22 North Florida
That's a good idea Gene. What has amazed me is how solid the cleat, and the deck above, feels. It's hard to get your eye that close to the area, but looking at the photos afterward, it looks like the plywood was only 1/4" thick to begin with. The layer of plywood I got to after cleaning out the rot is solid, and looking closely at the photos, it looks like it is just a single plywood laminate thick - the bottom fiberglass laminate is showing through in the cleat bolt photo. The fiberglass deck itself must be a substantial layup.

I was hoping it would not be a big job, but then again every project I tackle usually winds up taking about 3 times longer than expected. I'm not sure if cold beer has anything to do with it... or just the tricks of fate.

It sounds like anything you do is going to be stronger than factory original.

Wanna get really lazy? Instead of applying the epoxy onto the "ceiling" (which is a much bigger PITA than it sounds) just cut the piece of G10 to fit the entire area, butter it (the G10, rather than the ceiling) with a really thick layer of thickened epoxy, and stick it up there into place. Done!

Maybe the cold beer effect you mentioned has got the best of me, but from the way I'm looking at those pics, I actually think that's what I would do.
 
Jun 25, 2004
1,108
Corsair F24 Mk1 003 San Francisco Bay, CA
I repaired rotted balsa core under the mast step on my boat from the inside. If you want a nice smooth repair, you'll want to replace the core with glass (or foam?). Foam is very easy to sand down to the right thickness for a smooth repair.

Then you can press a new glass skin up against the foam, using release ply and bleeder cloth, some padding, and wood 1 x 2's to get a nice smooth finish.

I personally think putting a layer of foam in there is easier than using plywood or many layers of cloth.

You can read the blog here:
http://blog.f24-mk1-trimaran.com/

Then follow Maine Sail's instructions for attaching hardware. I think G-10 is heaver and thicker than you need for a backing plate for a C22 horn cleat. I'd use something thinner and lighter. Maybe 1/8" aluminum plate.

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IMG_1971-editted.jpg
 
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Sep 30, 2013
3,538
1988 Catalina 22 North Florida
Nice work, Dr. Judy!! :thumbup:

In your blog, you mentioned wetting out the roof with epoxy as a first step, which is worth repeating here no matter what method is used.
 
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