Roof repair help

I have rmoved the rotten plywood from the roof over the cockpit. I was hoping to use a closed cel foamboard to replace it, epoxied up to the gelcoated fiberglass top (flimsy 1/16 glass). Any help appreciated.

 

Welcome to the forum B.C., it would be helpful to get a better idea what you're doing. Can you post pictures and offer a better description (boat make model, year, etc.)? Have you removed a plywood substrate from below and now have a light mat and gel coat shell? You can use foam, but you'll need a good bit of laminate ('glass) to replace the strength and stiffness, lost with the plywood removal.

 

Ennos Roof

You are correct, I removed all the plywood, 3/4 inch, from the underside of the cockpit area of the roof. I'll try to post a picture. It's a 1981 Ennos 32 Trawler. Built in Vancouver for over 20 years. Good Glass Hull, but too many holes drilled in the roof. It apeared to have several different repairs. Some apeared to be poured in resin, about a 1X2 foot area that weighed about 25 lb. a couple of others that were smaller. Another 2 corner pieces were glued in with a construction cement. Areas around the patches were rotten, wet, heavy,and delaminated. I didn't think it was that bad until I got into it.

 

32 Ennos

A couple of pictures of the roof. It sounds like I will cut it off, turn it over, set the curveand glass in the laminates.

 

Yeah, that'll have to come down and get forced back into shape with a jig. The roof crown (camber) will likely be constant, at least it appears to be, so the jig will be easy.

Make a couple of templates of the front and back curves. Plywood works well for this. See if they're the same. If not (the back looks to have sagged a bit) select the one you think is close enough, which will probably be the front. Back two identical curve templates and connect the sides with some straight stock, say a couple of 2x6's. The top can be inverted and placed on this perimeter jig. You may need a few more of these curved templates in the middle, to help force out the sags and distortion.

You can use foam, honey comb, solid wood or plywood for this repair. Foam and honeycomb will require additional laminate ('glass fabric) to be on the edges, openings and the underside, completely entombing the whole roof, to get the required stiffness and strength. This is a fair bit of 'glass work and the materials not especially cheap. Plywood will likely be the least costly and simply is a few layers (preferably) glued into the roof crown. Lastly and what I'd strongly consider, would be solid or laminated wood beams. I'd make a perimeter frame of spruce or pine, then laminate or saw to shape, beams about the depth of the existing roof edges. These would be glued in on 16" or 24" centers, spanning the width of the roof and of course having the crown built in. The openings would also have wooden frames, all glued in place and encapsulated with epoxy. To further make it good to look at, I'd use alternating layers of light and dark colored wood on the beams and maybe the hatch openings, say pine and red cedar or oak and mahogany. All finished bright. Being under the roof, it wouldn't see much UV damage, so the clear coating or varnish would last a long time.

The plywood failed when holes where drilled and not sealed or previously sealed or bedded hardware failed and moisture got in. It offered 30+ years of service, so, not a bad way to go again. If the holes had been epoxy bonded, the roof wouldn't have rotted. The same would be true of a regular maintenance routine, replacing bedding and fixing loose fasteners as required too.

 

Ennos Roof

Thank you, that is the direction I will go. I agree that a plywood repair will last the life of the boat. The roof has only one opening. The opening on the Stbd side was the old heavy resin repair. a formed piece of fiberglass came off with the old resin repair. Thanks again for the help.