Flooring/Deck Thickness

I have a 16X52 ALLWELD Aluminum flatboat with a 50HP Johnson, steering on right side, with a 55 # thrust Minn Kota Great White trolling motor.
I have put some closed cell foam on the floor and want to cover it with plywood and carpet.
I also want to extend the front casting area by about 2'.

QUESTION IS: What thinkness plywood should I use and does it have to be treated or marine grade? Would I be better served putting the "astro turf" looking carpet or plain old outdoor carpet over the plywood. Or, just paint the plywood and make it non-slip some how.

Any other advise or direction would be greatly appreciated.

I used 5/8" on mine - same as what was there originally. Don't use marine ply. It's expensive and the chemicals in it may react with the aluminum. I used "off the shelf" plywood and coated it twice with fiberglass resin. Lot's of people report good results using marine varnish.

If you're fishing saltwater, you might want the deck to be a non-slip and easy to hose off. I hate the way astroturf looks on a boat but that's just me. Just be sure the plywood is sealed. Once that's done, its more personal choice than anything else. Good luck!

No pressure treated wood.

1/2 inch is plenty if you frame it well.

I have an aluminum deep v. I used 3/4 exterior grade plywood with three coats of exterior porch paint to seal it. I put exterior carpet over that. I have pictures in boat house. new member with 79 Sylvan rebuild.

3/4" is thick enough that it requires much less framing/bracing than 1/2". You end up lighter in the end

I built my trolling motor tray out of 1/2". That was a mistake. By the time I had it braced, I could have just gone with 3/4" and saved some weight.


Marine ply is best.
quality exterior ply is 2nd.


Gander Mountain is pretty cheap on carpet. I prefer carpet, and don't care for the astro turf stuff. Too much work doing all the modifications to a boat to not finish it out nice IMO.

There are a fair amount of folks that disagree with that theory.

If you are bracing with 2x4 it may be true...3/4 plywood is significantly heavier than 1/2 inch and the reduced spacing/slight extra framing should not be more. If ou find it heavier perhaps you went a little overboard with the framing, more than necessary or using 2x4's ect. You don't need that heavy of framing to make it work.

1/2 inch exterior grade ply is plenty and you don't need heavy framing to make it work. You can see what I did here:

https://www.tinboats.net/forum/viewtopic.php?f=3&t=19949

The ribs and glass in my build add weight but they stiffen up the system so much that no framing of any kind was needed.

My framing, at least for the main floor was the stringer system in the boat. 24" centers. 3/4" was the way to go.

Similar spacing is used by all new pontoon manufacturers, and they use 3/4" also.

Pontoon boats are the most heavy boats out there too.

Construction for homes uses 1/2 for most purposes.