"I could cut it, glue it, and screw it and not have to worry about welding," he says. Beckerman wanted to sit upright in the sub, with outstretched legs, and peer through a dome. So after sawing the pipe to size, he cut a porthole on top, added a skylight of ¼-inch-thick acrylic, and waterproofed the seams with marine epoxy. Four 10-gallon plastic water containers serve as ballast tanks, which take in or expel water to lower and raise the sub. He connected a 1.5-gallon air compressor to the soda machine's regulator and used a four-way splitter to feed air to each of the tanks. Using solenoid valves, he can activate the compressor, pump air into the tanks to expel water, and rise from the depths. Meanwhile, a trolling motor attached to the stern propels the sub.