Marine Grade Plywood Thickness

[sneak_e_pete]

Hi there. Going to be re-doing the floor and hatches of my boat. I am torn between 1/2, 5/8 and 3/4 thickness. My main concern is weight. I want to keep weight down as much as possible. What experiences do you have?

[Gerritt]

I went 5/8" with good bracing underneath.... Worked well.

[sneak_e_pete]

Thanks! Did you seal it? What did you use?

[SylvanOwner]

I've redone my floor, storages, hatches, casting deck....read "everything".....lol...on my 14'er and used a mix of 1/2" and 5/8". Had the same concern as you Pete....weight. The previous owner had a pretty good floor joist system on 12" centres. Just laying the 1/2" sheet on them, it felt a little spongy so I added some vertical cross-braces of cedar decking boards in between the joists, especially in high traffic areas. I think I won on weight in the end and it's very solid. I then got the notion to add to my casting deck, extended from the back end, and wanted to utilize the space underneath so I went with 5/8". There's a good 16" x 32" of unsupported decking and it's also very solid but noticeably heavier. I suggest sealing with a marine epoxy after all the cuts and holes are made. Noah's Marine in Etobicoke has all the goodies, super helpful people and reasonable pricing. When I asked how long they would expect the flooring to last (marine ply and epoxy) the answer was "It'll outlast you"....I was 40 at the time, 43 now, it's as solid as the day I built it. The storage hatches were done in Phase 1 so I used the 1/2" and had to be a little careful in my design to ensure enough support, ended up splitting 1 storage (1 was larger than the other) in half (electronics and "stuff") that allowed for a vertical support in the middle. I can confidently stand anywhere in the boat including on the storages with no concern about damaging anything. My motto was over engineer the design and then overbuild the engineering. Seems to have worked. I don't plan on doing it again on that boat....ever....another larger boat however.......

 

Oh, forgot to say, I used aluminum angle stock as backing for the pedestal bases.

Edited August 10, 2015 by SylvanOwner

[SlowPoke]

I replaced my wood floor with aluminium but the same consideration applies... If you have sides or bulkheads that are fastened to the floor you may be required to use the same thickness that was in there.

In my case I used 3/16" aluminium plate over 1/4" 2x2 angle supports to get close to the 1/2" voids where the sides and rear bulkheads met the old floor.

 

If this is not an issue, I would use 3/8" minimum and wouldn't be afraid to use 3/4". Marine ply is very lightweight.

[2 tone z71]

3/4 marine and just like your other post silicone..paint..or epoxy,varnish it and the cut ends

[tb4me]

Keep in mind what Slowpoke said above..If you want her to go back together exactly as it was the floor needs to be the same..If it doesn't matter then go 3/4 inch..Its super light...

[Smokercrafty]

Good post! News to me, was that marine ply density was less than construction grade ply, thus making it lighter. When I plan to redo my floor, I aim to collect all the scrap aluminum ladders I can find, and use them as my sub floor.

Then I'm torn between carpeting or brush on vinyl flooring. Been hearing pros/cons of both. Currently, I'm walking on a carpeted floor.

[wormdunker]

I did a job on the floor of my 14' Lund. I used the textured vinyl you see at Home Depot. Now you see the same vinyl in all of the new Lunds. I don't like carpet cause hooks are always getting caught in it.

[2 tone z71]

It's carpet all the way for me I like the comfort and warmth

[sneak_e_pete]

Thanks! What was the name of the vinyl coating you used?

 

I would really love a new boat, but spending $1k to fix mine sure beats buying new. My motor is a 2011 Yamaha and runs like a dream.

[dave524]

Join the iboats forums, there is a lot of good aluminum restores documented in the Starcraft Discussion thread.