For the annual trip to the lake, we decided to try and launch a model rocket with a b class engine from a launch platform submerged at least 3 feet underwater. We used PVC pipe and aluminum foil for platform, along with rope, a guide rod, nuts and bolts, rubber cement, a hose clamp, some rubber bands, and of course a healthy dose of Duct Tape. Heavy duty wire, some alligator clips, and a boat battery was enough for launch. We nailed a wooden board with an eye bolt to the boat dock to use as a pulley about 20ft under water. An all around success. Now we need a project for next year. Rocket boat?