Hi all,
I'm doing up an old dutch barge and I could do with peoples' wisdom about the floor...
The boat is flatt bottomed, and the floor lies on the iron ribs across the bottom. It needs to be removable as it sometimes pops leaks. the floor area is ~2.5m wide by 15m long.
I've acquired the shelves out of an old library to build this - tons of mahogany shelves 8-11 inches wide, ~2.5feet long, 3/4inch thick, and larger panels made of ~12"*1" oak planks.
My current plan is to float ply over the ribs with breathable insulating membrane on the bottom, and glue the planks to it, all laid out in such a way that they can be pulled up in sections...

What I specifically need advice on (feel free to comment on any other aspects too) is:
- what glue should I use? I was reckoning on using ~4 little spots of PVA per square foot, then sloshing on varnish - that way, if it all goes wrong I can reclaim the planks fairly easily
- I've been told that oak will warp given a change in humidity or maybe a temperature gradient, so it would be worth cutting longways slots ~2/3 through the planks every inch or so to allow them to bend. Is this true, and do I need to do this for the mahogany too?
- how much will the wood expand/contract, and how do I deal with it?

thanks in advance, I know this is quite a long demanding/rambling first post.

cheers

Jim Potter
bristol, UK

You could try the mahagony. But keep in mind, the term "mahagony" is really a generic name for very many species of woods and trees. So what species you have is unknown, and they do have different properties. Now if I was planning this and buying the wood, I would use either Ipe ( Brazilian Walnut ) or true Malaysian Teak. Both are very resistant to water damage and warping. I would not glue the planks to plywood. Instead, I would make simple panels that are manageble to handle ( 2 x4 ? ) and screw the planks to two or three other planks running the opposite direction. The way they would build old cottage and cabin type doors. Use stainless steel screws. You could try Spar marine varnish but that usually doesn't work well on some oily woods. Here in the states we have a phenolic resin tung oil finish called Waterlox that would be ideal for your application. Perhaps the UK or Europe has a similar product. After finishing, then lay the panels in place across whatever horizontial supports you have in place.

Texas Mesquite will handle the moisture issues!! I swear you could install it in a swimming pools and fill it with water and not see a problem.

True, except the guy is in the UK. What would mesquite cost there?

A while back with our dollar in the tank, it may have been affordable! Hehehe!

I didn't see Bristol, UK

Teak & Mahogany is what most boats have, for the resistance to rot.

Yeah, teak was, and perhaps still is, the premier boat deck wood. Mahogany was used more for boat cabinetry, doors, paneling, that kinda stuff. But around here, Ipe is the wood of choice for exterior decking, due to it's hardness, moisture resistance and rot resistance.