Marine propulsion systems have become increasingly electromechanical in recent years. Proposed systems show increasing torque density in an effort to reduce volume and weight. A magnetic gear is proposed to reduce the size of the propulsion motor and achieve similar torque amplification provided by a mechanical gearbox, without the maintenance and breakdown issues. A magnetic gearbox, of the concentric planetary type, will be studied for the high-torque low-speed requirements of a marine propulsion system. Torque ripple is investigated across multiple models to determine acceptable torque transfer performance.