I built this wooden boat from plans just for that purpose. It's called the Cobra 21, RCM plan 739, 30" long, 9" beam, Graupner Hydrospeed 7022 drive unit, 6 cell nicad car pack. I tape the hull shut with some coroplast. On top of that, I attach a chunk of foam that's higher than the float cross strut and lower than the bottom of the fuselage. Manouver the boat between the floats and drive everything home. Easier said than done if your plane is floating way out there. Other drawbacks...more stuff to haul down to the water, extra batteries and transmitter to keep charged, kids will run the boat and kill the batteries while you're flying!