Floor Boards

[UNCIVILIZED]

I'd say that cored panels are the way to go. The lightest, probably being carbon fiber skins, with a nomex honeycomb core. And a good bit cheaper, but still real light, would be; E-glass skins, with NidaCore plastic honeycomb core. Or, the standby; E-glass & foam, or balsa core.

You can get; Honeycomb, NidaCore, & Balsa Cores, for the same price per sqft (or less) than good marine ply. And putting skins on them is cheap, so there's little downside really.

If you want light weight, but with the traditional look, you can;
- Overlay wood veneers onto a cored panel.
- Use wood veneers as the top skin on a cored panel
- Use 3mm plywood as the top skin on a cored panel, & add colored striping, to resemble Teak & Holly. Either actually use a light colored wood to said effect, or just epoxy in place some lines of white sand or similar non-skid material. Including white skateboard tape in a pinch.

To those advocating sticking with the heavy, thick plywood floorboards, consider this.
If you go with a honeycomb cored, carbon fiber panel. Sqft per sqft, they're lighter than beer cooler foam. So the weight savings is HUGE. Just don't let anyone walk on them inn stilleto heels, as they punch right through the skins. As well discovered by the One Australia team during the '95 America's Cup ;-).

PS: Laying things under a vacuum, on a mold table is the way to go. You get a perfect finish, with zero work. And minimum weight in resin to boot!

[Cheechako]

1/2 ply probably weighs less than the 3/8+ vinyl. Good ply like Bruynzeel is a great way to go.

[UNCIVILIZED]

1/2" ply = 1.5lb/sqft (before sealants & coatings), so call it 1.75lb/sqft+

1/2" cored panel with E-glass skins, & pigmented epoxy finish = 0.65lb/sqft

1/2" Nomex Honeycomb cored panel with Carbon skins = 0.15lb - 0.2lb/sqft

[Pacey16]

I just made some floorboards from 20mm Nidaplast with a single layer of 600 gram CSM on each side, stiff enough and half the weight of the original ply boards.
Pretty happy for my first attempt but I will try Cloth with peel ply on the next ones and try and get them a bit lighter still.
I also only carry light beer when sailing, ha ha

[Cheechako]

Originally Posted by UNCIVILIZED

1/2" ply = 1.5lb/sqft (before sealants & coatings), so call it 1.75lb/sqft+

1/2" cored panel with E-glass skins, & pigmented epoxy finish = 0.65lb/sqft

1/2" Nomex Honeycomb cored panel with Carbon skins = 0.15lb - 0.2lb/sqft

Wow, are you saying a 1/2 ply 4 x 8 sheet weighs 48# uncoated? Sure doesn't seem that way when you lift it....

[UNCIVILIZED]

Originally Posted by Cheechako

Wow, are you saying a 1/2 ply 4 x 8 sheet weighs 48# uncoated? Sure doesn't seem that way when you lift it....

Look it up if you don't believe me. The weights do vary from species to species, & who makes it, how many plies, etc. But, pretty much, for Marine/ACX Douglas Fir 1/2" plywood, you're looking at close to #50/sheet.
Plywood Weight | ThePlywood.com

If you're trying to watch weight on your boat, it REALLY makes a difference to pay attention to what species & grade, etc. that you're using. That, & savvy boatuilders will put the lumber or glass cloth which they plan to use not too far down the road, into a drying box, so as to bake out as much of the moisture (weight) in it as possible.

Doing so, consistently, can save you an easy 10%+ in a boat's (hull) weight. Although it means; planning ahead, as well as using that glass or lumber in fairly short order after you pull it out of the drying box. And then sealing it up fairly rapildly afterwards.