With the 18 ft model and three men, the rig pushed a top speed of 13 mph. The 18 ft model ran best with about 9 psi in the floor, and 4 psi in the tubes. anything lower in psi, it decreased top speed. I measured the boat to be 53 inches in width. Stand-up paddling pushed it around at good pace. The prop clears the tubes by about 4 inches. One thing that I'm going to do though, is adjust the spherical ball joints on the motors, to get the prop to ride about 1-2" deeper in the water. Most small boats have a 13 degree transom (or somewhere close). The kaboat has a straight transom, so I couldn't get the prop as deep in the water as I would like. That's one of the good thing (of many) about the copperhead design, is that you can adjust them.