Brettski, I ended up using white styrofoam. This cut the cost on floatation down to 1/3 of the extruded polystyrene cost. The place I bought it from started with 20" x 4' x 8' slabs. I had them cut them to 10"x 2'x 8' which are the dimensions of the recommended extruded product. My understanding from the research I did is that it supports exactly the same weight and therefore could be the same dimensions. Only about 3 inches of the dock is submerged. You can run around or jump on this thing and it hardly moves. I think the corner pipes help stabilize it. I moved the dock out a bit farther last weekend and found it relatively easy to pull the pipes and re-locate it. I am purchasing longer pipes since the rising waters are about to overtake the length!
