bottom and inside sealer

Want to start ordering the supplies for my new boat build. Was thinking about using steelflex for the bottom of the boat. Now the questions I have is how much steel flex should I purchase? Its a 1464 sea nymph. Would a quart kit be enough to coat the whole bottom side? Just the bottom half, the rest will be painted with top side paint.

Next I was wanting to coat the inside of the boat with a sealer also. Just to double seal everything. What should I use to coat the inside with? A floor will be going ontop of it all but just want that extra seal.

For the inside you want a product call gulvit. Gulvit goes on the seams and rivets only so a quart should do.