deck - materials, tips

[ElBichoMalo]

I've been trying to psych myself up to replace my deck. Only had a few soft spots, but upon opening them up, I realized that all of the balsa is soaked. I just can't see finishing a boat, only to have the problem resurface later once fully rigged.

Planning to go with 1/2" marine fir (trying to limit cost, used Coosa for transom, Divinycell for hatches, why not plywood for deck, ha). Does anyone know how many sheets I will need? The hatches and coffin are all done, so just need the remaining deck areas? My boat is not at home, or i would just measure...

Also, how did you guys with experience make templates to cut out the plywood pieces? Luan strips? Cardboard? Anything better?

I am considering breaking it up into some smaller pieces to try to keep warping to a minimum...did anyone figure out a good way to prevent the wood from warping? I'm assuming (and read in some old posts) that the wood can warp after having only one side glassed. If only I could glass both sides at once....hmmm...

Lastly, any tips or techniques to working the areas around the hatches? I guess I would like to keep the lips, cause I certainly can't make new ones. How did you guys handle this?

Thanks guys, Evan.