An electrical linear motor for propelling a marine vessel comprises a thruster assembly disposed within a guide tube. Permanent magnets are attached to the thruster assembly and placed in close proximity to electrical coil windings, which are positioned outside of and parallel to the guide tube. Electrical current energizing the coil windings creates an electromagnetic field, which interacts with the magnetic field of the magnets to cause reciprocating linear motion of the thruster assembly with the guide tube. During the non-propelling back stroke, a check valve on the thruster assembly is in open position to allow free passage of water. The check valve is moved to a closed position during the working stroke of the thruster assembly, allowing the thruster assembly to propel the marine vessel.