Pontoon boat design question.

[sam_b]

I am planning to build a pontoon lake boat. The pontoons will be built using the ‘Strip Cedar Kayak’ concept with extra strength bulkheads. The dimensions of the pontoons will be approximately 20’ long and 2’ in diameter. The deck will be 7’ wide and 14’ long.
My questions are related to the design of the deck. Are there any calculations or designs out there that would give me some idea on structural safety for the deck? I have included the basic idea so that you may see how I plan to connect the pontoons to the deck. (Word Doc) The lines with the little circles at the ends are approximately 1” pipe. (Material yet to be decided.) The deck is designed to be about 1’/1.5' above the water line to allow the lake waves to pass under the boat.

Any ideas or comments would be appreciated.

Thank You.
Sam Bozman

[gonzo]

Cylindrical sections are only logical for metal. A hull with some flare or slab sided and a flat top is a better design. What are the longitudinal pipes for?

[sam_b]

The cylindrical pipes are to lift the deck above the water. I did not want the deck sitting directly on the pontoons as a previous design suffered from wave 'slap' during frisky weather. The design for the pontoons will have ‘shape’; I only drew them as round for example. The deck design is giving me the most problems.
I am worried about deck strength between pontoons while preserving weight.

Sam

[gonzo]

Make the hull with enough freeboard to get clearance and set the deck directly on top. Pontoon boat decks are usually 3/4" plywood with beams 16" apart.