Why not use plastic for floor replacement?

[austin27549]

Hello, 1st post:

I am replacing the rotten floor in a 1977 19' Hydra-Sports bass boat. A lot of work I know but it was my dad's boat so I really want to keep it and use it.

I've read post after post on the subject of floor replacement and it seems to me that plastic would be a much cheaper and easier solution than fiberglassed wood. I suppose there may be some concern with warpage or expansion on hot days in full sun but I can't help but think that plastic is still the answer.

I have several years of experience in the thermoforming plastic industry and I believe that ABS would be a very strong, durable, relatively light, and most importantly--rot proof alternative to fiberglassed wood.

I ripped the old floor out and found rotten supports in a few spots, mainly under the drivers seat. I never expected to see foam strips seperated by thin metal strips. They are pretty fragile.

Anyway, I'm thinking of replacing the rotten 1/2" to 3/4" wood floor supports with 3/8" ABS strips screwed together with stainless steel screws to double thickness and 3/8" ABS for the floor, with a total weight of about 100 lbs, and maybe $150 in materials. I would save a lot of money by not using fiberglass. Would silicon and stainless steels screws be sufficient to seal the floor to the "upper part of the body" (sorry, my first boat). I would be sure to leave cut-outs around the floor supports for water drainage. I haven't come up with a solution for the foam strips. Several people have suggested in their posts the use of plastic bottles but these strips are only about the size of a hockey stick or a tobacco stick depending of course on where you're from. (Go Carolina Hurricanes!)

So my question is, am I about to make a mistake or am I on to something?

Thanks in advance!

 

[Boomyal]

Re: Why not use plastic for floor replacement?

Having the floor firmly glassed to the sides of the boat is part of it's structural integrety. I don't think you can glass composites/plastics. Furthermore, I think that your weight estimate is considerably higher than the combined weight of 1/2 ply, resin and glass.

 

[tashasdaddy]

Re: Why not use plastic for floor replacement?

if it was cheaper the bean counters, at the factories would be making boats out of it.

 

[andy6374]

Re: Why not use plastic for floor replacement?

You can use composite lightweight core materials that are engineered for boat building, BUT....they come with at a price. Be prepared to dish out the $$$$$.

 

[DJ]

Re: Why not use plastic for floor replacement?

"Divinecell" is the name of the fiberglass "honeycomb" core building materials many builders use today in place of plywood. It comes in sheets, much like plywood.

It is $$$$ but is impervious to rot. It also can be glassed in place thus giving back hull integrity.

 

[Terrulle]

Re: Why not use plastic for floor replacement?

Austin, Have you heard of Azek trim board? It comes in sheets as well as planks. It is a white plastic.I've used it for precast concrete forms. Screws can be countersunk withouth drilling and it can also be glued with pvc pipe glue. Once glued it will not come apart and is water tight. I know that resin will bond to it as long as the slick surface is roughed up. the resin does react with the plastic (softens it) but when cured bonds quite well. How long? I don't know ,but it would be softer on the feet. I'm not sure how structural it would be either. It would also have to be painted so it won't blind you. T.

 

[Boomyal]

Re: Why not use plastic for floor replacement?

I also think you would be hard pressed to get any composites/plastics with the same rigidity as Plywood. Also, I wonder about the 'boards' ability to retain fasteners for every thing that needs to be affixed to the floor.

 

[andy6374]

Re: Why not use plastic for floor replacement?

I also think you would be hard pressed to get any composites/plastics with the same rigidity as Plywood. Also, I wonder about the 'boards' ability to retain fasteners for every thing that needs to be affixed to the floor.

Your right, twice. You have to use at least two layers of glass on the underside and topside of the core material to give it the necessary rigidity and it just can't be 9oz cloth or 1.5 oz mat. I like using 1708. You'll also need to put plywood backing pads where you plan to mount things with screws, if you are thru-bolting it isn't necessary.

 

[JB]

Re: Why not use plastic for floor replacement?

Seems to me that UV vulnerability would be a consideration. I have owned a "plastic" boat (Sportyak II). After too few years it got brittle from UV and was a total loss.