Recommended plywood and fiberglass?

[1970Thunderbird]

Hello,

I was walking around my boat this afternoon and felt a soft spot in the floor, which very rapidly turned into a hole. It's under the port side seating, and is about 2' by 2'. The boat is a '70 Thunderbird and, to my knowledge, has not had the flooring replaced. It was kept in a garage for most of its life, save for the year before he gave it to me.

Should I replace the entire flooring, or just fix the hole? I'm not opposed to doing the whole floor, and am in fact leaning towards doing so. Regardless, is pressure treated plywood ok, or should I use "marine grade" plywood? I've heard that term before, but I'm not sure if it's any different than regular pressure treated plywood. If it is different, can you recommend some place where I can purchase it? I live in a fairly large city, and have boat stores in town, but so far as I know, they carry little in the way of materials. They'd rather sell you a brand new boat. Would Lowe's or Home Depot have such material?

This is my first re-flooring and re-fiberglassing. Can you recommend a book or site I should read so that I make sure I do this correctly?

Also, with regards to fiberglassing the new flooring, can you recommend a good, non-slip fiberglass to use? I'd rather use non-slip flooring, rather than carpeting.

Many thanks!

 

[River's Revenge]

Re: Recommended plywood and fiberglass?

This is actually a easy fix. ya need to take your time but not that big of a project. Look it up on You Tube. they show pretty much a step by step knowledge. "cut an exploritory hole with a hole saw". Keep in mind there are stringers under the floor. so go slow until you see how the floor is laid out. a chisel works well. once you have your rotten wood removed then make a patch out of plywood. If you will be covering in fiberglass,, pressure treated is fine otherwise if you are just painting,, marine grade works well. and yes home depot or lowes should have all materials you need.

Good luck!

 

[1970Thunderbird]

Re: Recommended plywood and fiberglass?

You don't think that, given the boat's age, a whole floor replacement is in order? Also, if I just patch, how can I match new fiberglass to my current floor?

 

[erikpn]

Re: Recommended plywood and fiberglass?

You don't think that, given the boat's age, a whole floor replacement is in order? Also, if I just patch, how can I match new fiberglass to my current floor?

It is in order 99.9% of the time in a 40 year old boat with a soft spot. There is virtually always more rot where you haven't discovered it or seen it yet. Patches are a bandaid, and this is not an easy fix, but not an especially hard one either.

I'd go ahead and replace the whole thing anyways for peace of mind, but you can cut out and explore around the patch first if you'd like. Tear out any carpet in the way, get all around the seats and look for more black rotted wood or soft spots. Drill exploratory holes in the likely looking spots of the transom and stringers as well to check for moisture.

Marine grade plywood will rot too if left wet and uncovered. It uses a waterproof glue and moisture resistant woods with fewer voids.

 

[ondarvr]

Re: Recommended plywood and fiberglass?

Start by doing a search here on "soft spot" or rotten floor" it will explain a great about what needs to be done.

 

[NSBCraig]

Re: Recommended plywood and fiberglass?

Don't use pressure treated wood or marine grade. Just use cdx or if you want you can use a piece with a sanded face. Neither will offer any benefit once you glass them in and PT not only needs drying but already has lamination problems of it's own for the treating process, it's not what it's made for.