ROVs nad AUVs are intensively being used in the offshore oil and gas exploration and production, underwater pipeline monitoring and maintenance, surveillance nad rescue operation, military operation, marine and enviromental impact assessments, salvage operation and hydrographic survey. The electrical actuators provide several advantages in comparison with mechanically actuated systems. In this project, we have designed, developed and prototyped an electrically actuated thruster as a direct drive propulsion system based on a 3-phase permanent magnet brusless machine for underwater applications. The non-linear design and analysis of the permanents magnet brussless motor are entirely performed in propeller, thus providing a peak thrust of 25N for the underwater manoeurve. Critical maximum output torque and efficiency at 48Vdc battery supply. Other electromagnetic considerations such as maximum speed capability, maximum output torque and efficiency at 48Vdc battery supply. Other electromagnetic considerations such as cogging torque, slot numbers and pole numbers are also addressed. Half-effect sensors are embedded inside the motor structure in order for the motor to successfully operate in bldc mode. The optimized motor design has been prototyped and tested to work as direct drive propulsion system. The results obtained from the experiment conducted in laboratory in an open water testbed show satisfactory performance with a rated 15N continual bollard thrust at 1200rpm motor speed.