Mike. You haven't run a diesel electric submarine lately. Twin engines driving a single shaft for surface propulsion and using a shunt wound motor generator to charge the batteries while on the surface (plus compressors to charge the high pressure air system) and then switching to battery power when dived to drive the single shaft is pretty standard. It really gets interesting when you use an air induction system on a snort mast to run the sub a couple of meters submerged under diesel power. You can get a 60 foot submarine to run 16+ knots ay extraordinary efficiency because there's no wave making resistance to overcome. Add a few thousand litres of liquid oxygen and a closed cycle Stirling engine and you can free yourself from the surface for long periods of time running your diesel(s) submerged in a semi-closed cycle system that uses seawater to scrub the exhaust gases. It's expensive, but the wives will never complain about getting seasick. When it gets rough, just dive and you have the smoothest ride you've ever imagined. Much better than the best Rolls Royce or Gulfstream V. Bruce -- ======================================================================= L. Bruce Jones U.S. SUBMARINES, INC. President POSEIDON UNDERSEA RESORTS LLC Tel: 208/687-9057 Fax: 208/441-7478 E-mail: bruce@ussubmarines.com http://ussubs.com http://poseidonresorts.com "Design, engineering and construction of submarines and submersibles" "Submarine related consulting, sales and operations." =======================================================================