Advice on replacing wood floor and stringers in foam-filled hull.

[cheburashka]

I swore I'd never do this again after the Glassply from hell, but a good friend has torn into the floor of his Fiberform tri-hull and found just what you'd expect in a 35-year-old boat--rotten floor and rotten stringers. He wants me to help since I've done it before, and I'm at least willing to find out what he's in for.

The stringers are trashed. There's not even enough to pull out for a template. I can figure out the contours and set him up with new stringers, but I'm not sure how far to strip it down. Should we cut out the flotation foam and start with a bare fiberglass hull? Does the foam perform a structural function, or is it just there to keep the boat afloat if there's a hull breach? I'd prefer to cut it out and not put it back in, but I'm not sure if that would leave the floor weak or compromise the rigidity of the hull. He thinks we should just carve out the stringers and leave the foam, and put in new stringers with some kind of expanding urethane foam.

There's about 2 feet between the main stringers and the section of the inner hull that's level with the tops of the stringers, so I'm thinking cross-members to support the floor and leave the foam out. Anyone have any experience with this?

Thanks

 

[Bob_VT]

Re: Advice on replacing wood floor and stringers in foam-filled hull.

Moving to restoration

Rip out the foam....... chances are it is NOT for structure and if it is...... use two part at the END of the rebuild to add it back.

 

[HVAC Cruiser]

Re: Advice on replacing wood floor and stringers in foam-filled hull.

What Bob^^^^^^Said

Post some pics we love pics
If the stringers and the deck is rotted the foam is most likely waterlogged. In any case you are going to want to remove all the foam to be able to work properly. With regard to cross bracing,Lots of it has to do with the size of the boat. I added 1/2" bulkheads to my one boat to add deck support, but also to contain water section by section and direct it to the bilge just in case. I hve built-in bait wells in mine so there is always water below deck

 

[proshadetree]

Re: Advice on replacing wood floor and stringers in foam-filled hull.

I cross braced my baylinner floor with a 1/2 inch tube at the lowest point to get water back to the bilge. I also did not re-foam mine. I wanted it to be able to dry out or hopefully not get wet. She did great last year and i will never miss the foam. By sealing your boat with separate compartments inside in the event of a hole in the hull only a 1/2 inch stream can flow allowing the pump to remove the water and slowing inward flow till you can get it back to the trailer

 

[cheburashka]

Re: Advice on replacing wood floor and stringers in foam-filled hull.

Thanks for all the advice. This is an 18 foot open bow. We're on a small shallow lake, so flotation isn't an issue. Sounds like putting in stringers with the original foam in place isn't an option. That's good. I wasn't looking forward to working in those conditions. I'll probably put in new glassed-in stringers and cross braces and leave out the foam. Just seems to me like a better way to do it.

I haven't looked at the transom yet. It scares me.

I'll get him to work stripping out the old foam and the brown soup that used to be stringers. He's got two weeks to do that while I'm in Hawaii on vacation . I'll post some pictures when that's done. I'd put in pics of the current condition, but I don't think they allow dirty pictures on Iboats!

Out of curiosity, how much foam would be needed for the average relatively deep-hulled 18-footer?

 

[HVAC Cruiser]

Re: Advice on replacing wood floor and stringers in foam-filled hull.

I'll get him to work stripping out the old foam and the brown soup that used to be stringers. He's got two weeks to do that while I'm in Hawaii on vacation . I'll post some pictures when that's done. I'd put in pics of the current condition, but I don't think they allow dirty pictures on Iboats!

Out of curiosity, how much foam would be needed for the average relatively deep-hulled 18-footer?

The heck with the boat pics, how about some of Hawaii LOL
I am thinking a 2 gal kit would be plenty. With 2# foam a 2 gallon kit will give you 8 cubic feet. On my 1973 21 ft Cruiser cuddy cabin I used 1 1/2 - 2 gal kits or 12 cu. ft.

Have fun on vacation