It's not a dirt moving machine ,but I have always had an intrest in submarines.I built a model U-boat out of parts & stuff we had around the shop.The pressure hull is an air tank off a truck and the drive motors are 12 volt dc current heater motors.It pulls us around in a small "john boat" as it uses a umbilical cord of electric & air lines that go from the sub to the boat.The power source is a 12 volt battery and a air tank in the boat.We named it "U-505" after the U-boat at the museum of science & industry in Chicago IL.Its an awsome story & exhibit , www.msichicago.org/whats-here/exhibits/u-505/ Here are a few pics of myself & buddy matt testing out the model U-boat.Matt's at the controls and 25c is in the water making necessary ballast adjustments.