replacing fiberglass boat floor

dyerfish

Recruit
Joined
Jan 11, 2014
Messages
5
Hello iboaters, i have a 1988 stratos 266 fish and ski ,i just bought 3/4 exterior plywood for floor, i dont really want to cover this in resin at all or fiberglass it in,has anyone ever used anything else besides this technique to waterproof a boat floor,i would also like to use the foam sheet closed cell insulation instead of poor in foam ,i think it would be better for drainige ,and i would like to use some kind of paint and then maybe carpet it,i think this would be easier to replace in the future in case the need arises again , any info would greatly be appreciated,than you
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
If you do not seal the plywood with glass and resin, you are inviting the floor to rot out, followed by the stringers and frames. I cannot recommend that course of action. You can use 1/2" plywood, as it is plenty strong. Whatever you use must be sealed with poly resin and cloth. Screw the plywood to the stringers and frames with stainless steel wood screws. Pour-in foam is usually closed cell, so there is no advantage to using foam sheets. Also, you normally do not want water to get under the floor, so drainage is unnecessary.
 

jigngrub

Fleet Admiral
Joined
Mar 19, 2011
Messages
8,155
It would be nice if you could do it like that, but you can't.

Did you notice how the decking of your boat was fiberglassed to the sides of the boat when you were taking the old decking out? This is called tabbing and tying the sides of the boat to the decking keeps the hull from flapping and flopping and coming apart... tabbing the deck to the hull is part of your boats structural design. When the deck is tabbed to the hull and then completely glassed in it ties everything together and makes everything stiff and solid.

The expanding foam also adds structural support to your boat and hull keeping the weak fiberglass hull from being pushed in by the water pressure on the outside of the boat. The foam also displaces water by filling voids that can fill with water, a foamed void is a lot more water resistant than an empty void.

The only drainage your boat needs is what was designed by the manufacturer, probably just to drain any water off that gets on the top of the deck. If you foam all of the below deck voids and 'glass in your deck properly there won't be any water getting below deck to drain.

If you want a boat with a deck that's easy to remove and has below deck drainage, buy an aluminum boat... that's what tinnies are all about.
 

jbcurt00

Moderator
Staff member
Joined
Oct 25, 2011
Messages
24,829
the deck also ties the 2 sides of the boat together, across (as well as fastened to) the stringers via the tabbing between the deck & sides of the hull

I recommend the rigid foam insulation sheets for aluminum boat builds, but, IMO, pour in foam is a much better option for a fiberglass boat. Do everything in you are able to minimize water intrusion & it's impact on your boat. Waterlogged foam & wood rot do not happen overnight, it takes time. Sometimes a great deal of time.

You plan on rebuilding the boat, so rebuild it to the best of your ability. Then why not take care of it when you're done, rather then letting it succumb to poor maintenance & careless ownership?
 
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