I built one last year. Built it as per plan but I wasn't satisfied with the dynamic submerging aspect. So I removed the recommended gel cell battery, constructed ballast tank from sheet plastic and placed it where the battery used to be. Bought a ballast pump from Subtech, rigged a couple of micro switches to a micro servo for pump in/out operation and used NiCd's for the power source. Ballast tank vents through periscope using silicone fuel tubing and pumps the water in/out through rear WTC bulkhead. I have it set up so when ballast tank is full just the conning tower is visible. Also installed micro servo in forward WTC bulkhead for bow planes and a auto leveler for the stern planes (also from Subtech) Sweeeeet. My next project is trying to locate suitable mechanical or electrically controlled air valve to keep water from seeping into ballast tank when ballast pump is off. [:@] Oh well, back to the drawing board.

Good Luck with you Seawolf,

G dog ...........out