A propulsion system for a submerged vehicle which operates at a relatively low RPM includes a pair of coaxial drive shafts for producing counterrotating torques. A first propeller unit is attached for rotation with one of the drive shafts and a second propeller units is attached for rotation with the other drive shaft. Each propeller unit includes a plurality of arcuate propeller blades which are deployed upon rotation of their respective drive shaft. Specifically, this deployment is from a first configuration wherein the blades are disposed along the surface of the vehicle and into a second configuration wherein the blades are extended from the surface of the vehicle.