 Other propulsion thrusters like outboard thrusters which can be easily put in and out of service, rim drive thrusters that operate from an external ring with the blade facing the center of the thruster or tilted thrusters pointed away from the hull to minimize interaction with the ship and increase thruster efficiency.There are different schools of thought as to why thrusters would be used to propel marine vessels as opposed to traditional propellers, but it boils down to versatility and efficiency.propellers are designed to work in-line with a propulsion plant and produce one-directional thrust while thrusters are more customizable and have a more versatile application.