[kach22i]

http://smalloutboards.com/pumpjet.htm

In the 1990's, the U.S. Military recognized the need to develop an outboard motor which could be used safely night and day for training exercises with men and equipment in the water. Attempts to adapt cages and guards to open propellers resulted in unacceptable performance losses and decreased engine reliability. The Pump Jet provides added performance, safety, and reliability to outboard motors.