Fiberglass Tub Repair Thoughts

I picked up a never been on the road glass tub today. It is a CJ5 tub from an unknown manufacture. No holes for a top, no holes for a dash but it has been mounted because there are 4 mounting holes where it was not quite fully mounted but on the frame enough to be on the frame.

It has a little damage that needs repair. The big question I have concerns the inner support (plywood) between the layers. This is the second glass tub I have used and all of the wood, in both tubs, have been rotten. IN this one, it was so bad the wood had deteriorated until it was basically decomposed to mud in places. I cut the bottom out and used a putty knife to scrape out the wood. It was stinky and nasty. Yaa fun.

In my CJ6 I replaced it with pressure treated 3/4" ply. It worked well but I know the water will get inside again through the bolt holes where it attaches to the frame.

So now that I'm doing it again, any thoughts on what to use instead of PT ply? Aluminum? Diamond plate? Another composite? Or anything you can think of to sleeve the hole for the mounting bolts so it remains water tight?

Or should I even worry about it and just use the PT and be done with it and not worry about the wet.

And since we like picts...

https://goo.gl/photos/nwmpSqZcLZzSToid6

https://goo.gl/photos/t1AfpnovsrsRUmkZ9

https://goo.gl/photos/ufYqUUfqMEZYctGa6

https://goo.gl/photos/AAYpRUmfr8YUBmDb6

And why did the picts not show up?





When I made the initial cuts on the lower corner, water poured out like I was killing it. I bet there was at least a gallon of water in each of the three sections.






This was the better of the two front plywoods


And the other side


The rear


The guy I got it from has several jeeps. He is about 3 years away from retiring as a Master Chief in the navy. I think it was Master Chief. Very nice guy. He did not know about us so I encouraged him to take a look and join. I believe he said he always used the username of Swamp Donkey.

Anyway, once it dries out, this will be the next CJ project. I need to start a build thread once I get the samurai out of the garage. Then I'll have both CJ's in the dry. Yaa.

 

look at a boat type place they have a honeycomb composite they use in floors,or at least they used to if not pt plywood will hold up the best. i'm thinking about a metal sub-frame on mine to help with the inevitable droop. a quick google got this,
Core Materials for Composites, PVC, Balsa, Coremat, Divinycell

 

Substitute for Plywood: Plascore Panel, Laminated Panels, Standard Honeycomb Panel Sizes

 

Another thought is to isolate the plywood at the body mount holes. In fiberglass boatbuilding, it is common practice, especially with balsa cored decks, to drill out mounting holes to a larger size then fill them in with epoxy. When you redrill the mount hole is will be solid epoxy with no access to the plywood inside.

 

I thought about this but I assumed the epoxy would be very ridged and inflexible and would crack out very easy. I also thought as the bolt was tightened, it would break the epoxy. I thought about making a sleeve out of aluminum tubing.

 

That may be so, but I would think no less stress than that of a sailboat stanchion or lifeline. You would more than likely want as little play in the tub as possible, with any movement being in the body bushing. There are also new epoxies that have some give as well, if that were a concern.