Stiffening Dinghy Floor

[bcripps]

I’ve got an old 12-foot Carolina Skiff I’m using for a dinghy. The inner hull (the floor), is badly cracked exposing the foam. It noticeably undulates under minimum speed. I am planning to repair this by laminating in a couple of 3/8-inch sheets of ply (thin enough to aid in bending to the contour of the floor), with layers of glass roving and mat. The boat is polyester but I’ll use epoxy for the repair.
I would appreciate ideas on a laminating schedule or any other helpful ideas. I’m in the DR so resources are limited.
Thanks everyone,
Bry

[coopec43]

Originally Posted by bcripps

I’ve got an old 12-foot Carolina Skiff I’m using for a dinghy. The inner hull (the floor), is badly cracked exposing the foam. It noticeably undulates under minimum speed. I am planning to repair this by laminating in a couple of 3/8-inch sheets of ply (thin enough to aid in bending to the contour of the floor), with layers of glass roving and mat. The boat is polyester but I’ll use epoxy for the repair.
I would appreciate ideas on a laminating schedule or any other helpful ideas. I’m in the DR so resources are limited.
Thanks everyone,
Bry

Have you checked YouTube? for ideas?

Why don't you google "repairing 12-foot Carolina Skiff floor"

I wouldn't use epoxy anyway. There'd be nothing wrong with using vinylester,

https://www.youtube.com/watch?v=tr1VxOTk91U

[bcripps]

Thanks for responding coopec...
Yes, I did watch vids originally, but most seem based on larger boats and produced by guys with lots of tools and a decent facility in which to work. I’ll be basically working on the beach. Also, at my location in a small fishing village in the DR, I don’t have access to things like biaxial cloth. So it’s plywood (not marine grade), and a mixture of cloth, mat and roving. In the video series you provided, (further on in part 9, I think), he uses 3 layers of biaxial to come up with what looks to be a finish thickness of 3/16 of an inch. That was helpful. The best I can come up with is a layer of cloth, two layers of 3/8 plywood, a layer of roving followed by a layer of mat. But all that is just a guess on my part. Might be a case of try it and see… and be prepared to add fore and aft stringers if necessary. Unfortunately they would be inside the boat and something else to stub a toe on.
Thanks again,
Bry

[bcripps]

A photo of what I'm dealing with... Bry

[Cheechako]

Originally Posted by bcripps

A photo of what I'm dealing with... Bry

So are you cutting and removing all the old foam? It must be filled with water and heavy.

Laminating will create a bit of a box beam but I would go thicker. Narrow strips of thicker should bend readily. But if you are fully laminating them to be enclosed, even some foam or lightweight product will work. Or multiple layers of ply strips I suppose. It's the fiberglass box that will give you rigidity. The taller they are the stiffer a box beam is created. 3/4-1" would be nice.

[bcripps]

Thanks Cheechako,
No. I’m not planning to remove the old foam, just let it dry out for a couple of months in the tropical sun. Then laminate two layers of 3/8 ply to make up 3/4-inches of wood. I’m thinking of using two layers of ply to aid in conforming to the bottom of the hull. What I need to know is how to laminate this wood to the existing hull? How many layers of cloth, mat or roving to use to ensure a stiff hull that won’t delaminate with flexing? Will two sheets of ply be enough? And what glass to use and in what order should I laminate the layers?
Any further information is much appreciated.
Bry

[bcripps]

Okay. I’m not getting any specific information as to a recommended layup schedule so, from the ground up, here’s what I’m planning:
1. Grind out the cracks, fill with thickened epoxy and reinforce with cloth tape.
2. Cover the complete floor with a layer of mat.
3. Lay in a sheet of 3/8 ply, saturated, and set in thickened epoxy, from chine to chine and beveled along the leading edge.
4. Add new chine logs of 1x2 lumber to tie plywood into the boat sides.
5. Lay in a second, longer sheet of 3/8 ply, with a beveled leading edge, between the new chine logs
6. Fill and tape all raw edges.
7. Add a layer of roving and finish with a layer of mat and paint with polyurethane if I can find it locally.
If anyone can see a glaring error in this, please bring it to my attention.
Much thanks, everyone…
Bry