Floor down to fiberglass-now what? I searched!

[stripers9]

After 3 days of grinding and belt sanding and cussing, there is nothing between me and my garage floor but a clean fiberglass boat floor in my old Monark trihull. The boat never had any stringers from the factory, the thin hull is what you stand on. The floor that I removed resembles good garden mulch. After searching on plywood, epoxy vs. polyester, mat types, etc. I still cannot figure out what to do next. I need to do this on the cheap as much as possible, so would a plywood floor replacement with NO stringers be the thing to do? Or would adding stringers (none now from the factory) and using an expanding pour foam be a better idea? If I use foam I would have to build an upper deck of course so you have something to stand on. The boat doesn't have squat for flotation right now from the factory. Would the foam add any structural strength to the hull once it sets, or will all strength be derived from any added stringers? The hull has some curvature, so if I do a plywood/glass floor only, I would have to use 1/4" plywood and "laminate" it in more than one layer to conform with the bottom shape of the boat since 1/2" won't bend so well. Thanks!!!

 

[Bondo]

Re: Floor down to fiberglass-now what? I searched!

After 3 days of grinding and belt sanding and cussing, there is nothing between me and my garage floor but a clean fiberglass boat floor in my old Monark trihull. The boat never had any stringers from the factory, the thin hull is what you stand on. The floor that I removed resembles good garden mulch. After searching on plywood, epoxy vs. polyester, mat types, etc. I still cannot figure out what to do next. I need to do this on the cheap as much as possible, so would a plywood floor replacement with NO stringers be the thing to do? Or would adding stringers (none now from the factory) and using an expanding pour foam be a better idea? If I use foam I would have to build an upper deck of course so you have something to stand on. The boat doesn't have squat for flotation right now from the factory. Would the foam add any structural strength to the hull once it sets, or will all strength be derived from any added stringers? The hull has some curvature, so if I do a plywood/glass floor only, I would have to use 1/4" plywood and "laminate" it in more than one layer to conform with the bottom shape of the boat since 1/2" won't bend so well. Thanks!!!

Ayuh,.... Boats don't have Floors,... They have a Deck,.. Cockpit Sole,.. Etc... No Floors....

For the rest of your Questions,....

Got any Pictures,..??

 

[ondarvr]

Re: Floor down to fiberglass-now what? I searched!

You didn't mention the age or size of the boat, but many of the smaller boats don't have stringers and if the boat is 30 years old and it's held up this long there's no reason the change it now. For a cheap fix just replace what was there and seal the wood better, this won't cost more, just takes a little more time to do it right. AS for epoxy or polyester.... that's for you to choose, do a good job and it won't make much of a difference.

 

[a70eliminator]

Re: Floor down to fiberglass-now what? I searched!

What do you mean by the thin hull is what you stand on? You belt sanded away some sort of structure.
Are there any ribs ?
There had to be something supporting the deck you removed.

 

[oops!]

Re: Floor down to fiberglass-now what? I searched!

i agree....we are going to need some pics of the craft.....im guessing a 12 -14 foot glass trihull row boat here.......alot of them didnt use stringers.


.....did you grind away any of the fiberglass hull?....(from the inside)

you can get away with grinding a little.....but if you took a lot.....you will have to add a layer of glass.....(when you walk on the hull now....is it really weak?)

you can just go 1/2 inch ext grade ply cut to fit the curvature and glass that in to place......if there was foam in it .....just replace it and done !

 

[stripers9]

Re: Floor down to fiberglass-now what? I searched!

Sorry for the lack of pics and manufacture info. Boat is an '80 Monark trihull. The belt sanding that I did was only to remove the remnants of the previous attempt that I made at fixing this. I tried to use 1/4" plywood and make it comform to the bottom of the boat. It did somewhat, but the voids that were not filled with resin obviously filled with water and rotted the deck wood again despite my glassing the 1/4" before I installed it. It was done on a new college grad shoestring college budget, and it lasted 10 years so I got my money out of it. I just want to do a better job this time, and the hull in this boat always seemed flimsy even when my dad bought it. The pics show the remnants of the factory chopped strand, and they topped the chopped strand with a very thin layer of wood and glass to form the inside wearing surface for the deck. I think that I need to fill in the low spots that I have now to make a more uniform surface to which I can attach whatever plywood I decide on. From what I have read, there's a lot of debate on plywood, but I'll use marine grade if I can afford it. Would resin and microspheres make an appropriate putty to level thing out? I'm thinking: Level out the low spots, apply 2 layers of 2" chopped strand, 1 layer of 1/2" plywood sealed with epoxy or polyester, top with indoor/outdoor carpet for aesthetic purposes. I guess the idea is to cut the 1/2" plywood into strips in order to conform to the hull better and fill in between the "boards" that are formed although more gaps mean more chances for water to enter. Thoughts?

 

[Bob_VT]

Re: Floor down to fiberglass-now what? I searched!

I am having a problem with this.

Based on your photos everything is basically flat but you say the boat is a tri-hull.

I do not see the outline or indication of it's exterior shape (based on your pictures)........ are you sanded down to the hull? OR are you sanded down to the point where there is fiberglass with foam under it.... then the hull.

Others might agree with me.

 

[ondarvr]

Re: Floor down to fiberglass-now what? I searched!

It is a little difficult to tell just what it looks like from the pic, but I think it's almost flat with a V at the bow, the tri hull part is almost just a reverse chine.

There are two ways to go, if you want a flat floor make some stringers to support it and put sealed plywood down on top of them, leave the front and rear open so water can flow freely under it. This allows you to easily drain it all out when you put it on the trailer. The other method is just put a layer or two of glass over what's there now and put a non skid finish on it.

1/4" plywood will add some stiffening, but will be a real hassle to get down and glassed in place. It would be easier to use something like core mat, it would stiffen it some, be easy to lay down and won't rot.