Re: 16' John Boat Floor Installation
I just got done doing something very similar with a Starcraft 14' aluminum hull.
On this one I ran a single wood stringer down the middle, matching the taper of the keel versus the hull's spray rail ledge. I ran the deck from just below the rear bench, up to about the front edge of the front bench. The floor will end up being flat snug up against the bottom of the factory bench seat bottoms. I then will mount pedestal seats on top of the benches.
I used 1/2" ply, and the only seam in the deck is under the middle bench seat. The center stringer that I added was cut from a 2x6 and simply glued in place with some 5200. The deck is screwed every 6" down the center to the keel and to two reinforcement panels along the seam to keep the deck from warping or opening up. The outer edges of the deck are set snugly into the ledge on each side, each panel set in place and pushed tightly forward to where it belongs. I'll just give the deck a final coat of heavy epoxy paint for now with some grit for traction. The deck slopes upward towards the bow area about 2 1/4" or so. It's not noticeable when in the water and actually seems to help the stability of the boat over a deck set lower or flat along the keel. Adding the deck also made the boat feel bigger as it gave more flat foot space, and the bit of space left open under the forward deck makes for the perfect place to store life jackets and other odds and ends. I stopped the deck short of the transom so as to be able to access the bilge, allow the battery to sit lower in the boat and out of the way of the motor when tilted, and I used the last section beyond the last rib as a battery tray, with a 1/4" rubber mat under the battery box with a strap between the rib and the transom. I had some concerns as to adding too much weight as well as to how the deck would 'feel' in the boat, but the result was absolutely perfect. It made the boat so much nicer to use and so much more comfortable on the water.
I attached a few pics of the deck in progress to show how it sits in the boat.
The area most improved by this design was the bow area, it made the forward bench area usable as where before you had to walk in the V portion of the hull, basically only in the middle. Its a far easier boat to keep balanced now. I used 1/2" ACX plywood, one 2x6 cut to fit, just over 8' long to span the fore and aft ribs properly, and about 30 1 1/4" SS wood screws. I'd say the overall weight is about one full sheet of 1/2" ply, plus another 1/4 sheet and the keel board. About 80lbs in all I guess. The seats are padded fold down bass boat seats on steel pedestals, the bench tops are now made from red oak. The deck is painted on all sides with 3 coats of light gray epoxy paint. The boat is powered by a 9.8hp Mercury, its gets on plane with two guys at about 600lbs total weight onboard, so the deck and seats didn't ad that much weight. A 20hp makes it move a lot better but we've got a HP limit here to deal with in several lakes. Next is to permanently mount the fuel tank in the bow. I may opt for a small V shaped tank with a permanent fuel line under the deck. This will be the icing on the cake as far as it's handling and running speed with the small motor.