First floor repair ever... (help me not screw this up!)

[Sixdekkers]

I apologize if this isn't the right forum, i didn't see one for "repairs".. I have a 70's 16' Larson I just got for fishing. Outboard, V-hull.

Issue:
i found a soft spot. i pulled the carpet back and found that someone had drilled a few small holes whenever and water seeped in rotting a area. seems about 24"x12" or so. the glass wasnt adhered to the wood there and crackling up, and squishing some water up from the soaked plywood underneath,

Sooooooo... seeing as how thats obviously needing to come up i took my skill saw and cut just deep enough to go through the glass a little larger than the bad area, and removed the glass.. then did the same with the water soaked rotten plywood. i hope this was right?? i just couldn't see glassing more glass over water soaked plywood that was rotten..

now... i can see foam (that seems a little water soaked, is this ok?) and also a stringer (?) .. that has a kinda soft spot but small and not through and through..

so pros, what from here? do i toss in a piece of good plywood, and just glass over it, or is there more painful summer ruining work ahead?

[Sixdekkers]

you get the idea...

[lazeyjack]

if it were me matey, I would get on ebay and buy another, better, bigger and with no problems, and have a happy summer get on the briny, fishing rod at hand, slab of beer, and , nice bird and there you are, no more worry

[jimslade]

How much do you like the boat? Its a lot of work. The stringers are probably gone and the transom too. Major work, but can be done. Lots of grinding and itching. Most cheap boats are soft and rotting.

[Sixdekkers]

Ok i think everyone got the wrong idea, this is NOT the whole floor.. its one side, one spot, and the section is only 24 inches x 12 inches total and thats with over cutting to get to dry solid wood all the way around..

[SamSam]

Screw some cleats on the underside of the floor around the edge, toss in a piece of good plywood, screw it to the cleats, and just glass over it.

[Bergalia]

With SamSam on this - but try and put opposing bevels (scarfs) on the 'new' insert - and the existing decking, to give that little extra strength to the repair.

[SamSam]

Originally Posted by Bergalia

With SamSam on this - but try and put opposing bevels (scarfs) on the 'new' insert - and the existing decking, to give that little extra strength to the repair.

I was going to suggest that but it didn't look like enough room for the saw. It wouldn't be too awful hard to do though, even if some of it had to be done by hand and it wouldn't have to be an exact fit with the cleats to back it up.

What it means Sixdekkers, or at least what I mean, is the hole in the floor would have say 45 degree sides and the ply patch would have 45 degree sides so the patch could sit in the hole by itself without falling through even if the cleats weren't there. The sides would be buttered up with thickened resin to fill spaces and then the patch screwed to the cleats, then the works glassed over.

[the1much]

they say that once your foam has been water saturated that its useless after that, gives no boyancy, and they( engineer wonders) say it should be replaced. and how "much" water has been in there, does it look like its been a swimming pool for awhile? i'd want to find out if it was jus regular seeping or if i had a water prob,ie-leak, or if my sump pump wasnt workin correctly

[USCGRET/E8]

A couple years ago I removed all the saturated foam from under the floor on a Correct Craft ski boat. It probably weighed at least 500 lbs.

[Sixdekkers]

cleats? what are they?

[Sixdekkers]

Samsam-
i don't have the room for a saw to do a 45 on the side near the innner wall, and that sucks because thats the side that only has foam and no stringer near the wall..

i can get cleats, anyone got a picture of how these are installed?

USGRET-
the center strip front to rear of the boat is hollow under the floor, with foam on the sides only it appears, and only finding wetness on the damaged side, i went back to the sump / drain plug area and drilled a small hole at the lowest point going into that cavity, and maybe a cup of water came out, thats it, although the foam still is kinda wet.. i talked to a boat shop by my work, their tech said patch it and glass it, he said that the foam will never lose the buoyancy..

i suppose i could go drop it in the water and see if it lists from extra weight

[Sixdekkers]

just found this cool page, for anyone with foam questions..

Pour Foam FAQ's

Q. How do I know how much foam I need to float my boat?
A. Great question! Get your calculator ready, you will need it. A cubic foot of foam will float about 60 pounds of "dead weight". The wood parts of your boat will probably float, so you don't need flotation foam to offset that weight. The fiberglass parts of your boat will barely sink, so you really don't need much foam to offset the fiberglass- maybe one cubic foot of foam per two hundred pounds (or more) of fiberglass hull. The metal parts of your boat are what you really need to account for. A small (4-6hp) outboard may weigh 45-55 pounds. A 50hp outboard will weigh about 200 pounds.

So a 16 foot fiberglass skiff with a 50 horse outboard will need about six cubic feet of foam to keep it afloat. A 12 foot plastic kayak will only need one cubic foot. A 30 foot fiberglass sailing sloop with a diesel engine and lead keel would need about 150 cubic feet of foam. Actually, very few 30 foot keelboats have positive foam flotation, but it's not out of the question- especially when you consider all of the air pockets that would exist, as well as all of the wood interior components that provide some positive flotation.

Q. Do I need to paint or fiberglass over the foam?
A. You can, but it's generally not necessary. Urethane foam will absorb a small amount of water, because some of the the cells are open (95%+ are closed, though). Painting or glassing will seal the foam and prevent any water absorption, but it really shouldn't be necessary unless the foam is constantly immersed in water, such as in a boat with bilges that are always wet. The foam is not UV resistant, so it should be painted if exposed to sunlight.

Q. Is the urethane foam resistant to fuel, oil, and solvents?
A. Mostly yes- It is resistant to gasoline and diesel fuel, although it will absorb a small amount because no pourable foam can be guaranteed to be 100% closed cell. A strong solvent such as acetone or toluene would eventually break the foam down, but it would take a long time.

[SamSam]

Originally Posted by Sixdekkers

Samsam-
i don't have the room for a saw to do a 45 on the side near the innner wall, and that sucks because thats the side that only has foam and no stringer near the wall..

i can get cleats, anyone got a picture of how these are installed?

You could do a 45 with a chisel or something, it doesn't have to be perfect. Thickened resin would take up any spaces.

You might be thinking of the wrong kind of cleats. What I'm talking about would be say 1" x 3" x ?? lengths of wood that you would glue and screw to the underside of the hole so half the width (1 1/2") of the strips/cleats would stick out and they would form a lip/ledge around the hole that the patch would sit on. The patch would then be glued and screwed to the cleats also. Do you see what I mean?

[the1much]

you could 45 it with a jig-saw, they have blades made just for fiberglass,, they thick ones that look like they got a bunch of dirt glued to em, and pretty cheap for a pack