OSSA POWERLITE^{®
Diesel-Electric Marine Propulsion Systems and Accessories}
 

Project Description:

Proteus is the largest of the Exomos submersibles and a very unique yacht.  It will, of course, carry passengers in the luxury expected of any high end yacht at the ocean's surface.  However, if anyone gets bored, a little queasy, or just wants to visit with the fish, it can submerge (to a depth of up to 18 meters) and carry them at speeds of 5 knots for a distance of up to 50 nautical miles.  In its military version (designated "SPV"), the gunwales are removed, larger motors added and the interior reconfigured.  With increased payload capacity and added armaments, it becomes the vehicle of choice for stealth diver delivery and patrol missions in the warm, shallow coastal waters of the Persian Gulf.

Such a specialized application requires a specialized power solution.  While the OSSA Powerlite system does not exclude "hybrid" configurations, for most yachts, we find that a pure diesel-electric system (i.e. one without batteries) makes the most sense.  Obviously, for Proteus underwater operation, battery power is a must.  An added complication comes from the large difference between surface speed (25 knots) and submerged speed (5 knots).  The high speed surface operation requires much greater power and energy efficiency is not particularly important.  When submerged, the propulsion power requirement is far less and energy efficiency is of utmost importance.

The widely varying demands made on the Proteus propulsion system provides a perfect case study of the proper application of a true "hybrid" system.  On Proteus, a conventional diesel engine is coupled through a three-way transmission to a specially designed OSSA Powerlite motor/generator and also the boat's  propeller shaft.  The transmission is designed to allow any combination of input and output shafts to be engaged.  For surface operation, all shafts are engaged at the same time so that the diesel engine is used to simultaneously drive the motor/generator (in "generator mode" to re-charge the battery bank) and to propel the boat.  On extended surface trips or other times when the battery bank is fully charged, the OSSA Powerlite motor/generator can be disengaged and the boat powered in the conventional direct-diesel manner.  For underwater operation, the diesel engine is shut down and its shaft disengaged at the transmission.  The motor/generator (now operating in "motor mode") propels the vessel using power stored in the battery bank.  On the military model this pure electric mode can also have stealth benefits on the surface.

The OSSA Powerlite motor/generators on Proteus have been designed to provide the full rated motor capacity at only 400 rpms and an identical output capacity (at higher rpms and higher voltage) when functioning as a generator.  This low turning speed and a design efficiency approaching 99%, maximizes the range and speed of the vessel when under battery power.

Project Photos