Diagram of the pontoon structure. The cross pieces (the odd shape cut out of plywood) will actually be 4 feet apart. The raked up front angle is not figured out exactly yet.

this is the end view of the raft. The dimensions are a little bit wrong in this picture, the A frames are attached at approximately 10 inches in from the edges of the pontoons. The pontoons are the larger of the two drawn, at 4 feet wide instead of 3 feet wide. The pontoon drawn here is a preliminary sketch of the finalized shape shown below.

This is the top view of the deck framing, probably made with 2x6" beams, and finishing only just outside the outer more "joist" of the pontoon at about 10" in from the edge. The deck will extend out to the edge of the pontoons if not a little farther as a sort of bumper.
The joint between the pontoons, the deck and the A frame. The pontoons will be solid independent structures from the deck/building (which will be built as one cohesive unit). The pontoon and deck units will be attached at two points along the width of each pontoon and at 5 places along the length of the raft. They are through bolted with a large rubber shock (made from traffic cones or tire pieces) between them.

This is the shape of the pontoon, made of about 5 of these shapes cut out of plywood and attached with a skeleton set into the shapes themselves. There will be through holes in these pieces to allow free flow of water in and out of all parts of the pontoon.
The top view of the raft. This diagram only shows 3 a frames but we will probably use 4 at 4 feet apart each. The "roof" will be a rope net suspended between the a frames which will provide storage access to the waterproof roof covering the a frames and a sort of sun deck.