The SEA MAX THL-404-8 Thruster is the result of more than 20 years of deep ocean engineering experience in the design and manufacture of ROVs. It provides up to two shaft horsepower and is extremely reliable, even in the demanding underwater environment and during long, continuous use. It is a true brushless servo motor thruster that permits very exact output power regulation and is therefore ideal for use with precision feedback systems such as autodepth and autoheading.

The thruster is powered and controlled by a vector drive type electronic drive module (EDM), one EDM for each thruster. The EDM provides up to 2.5 kW of power in a closed loop, factory calibrated system and controls the motor speed by estimating the orientation of the permanent magnet flux vector to determine the thruster motor shaft rotational position. It connects directly to the thruster and is powered from an AC or DC source over a range of voltages. The drive does not require that a resolver be installed in the thruster for motor commutation, yet it is fully backward compatible with earlier THL-404-8 Thrusters which include resolvers and use resolver type EDMs. The drive also includes an RS-485 serial interface which is used to configure the drive and to monitor its performance using a PC or other host computer.