The NAIAD HMG (Hydro-Mechanical Gyroscope*) roll controller is a completely automatic, extremely sensitive, self-lubricating and highly responsive system for fully proportional roll stabilization control. The HMG has been proven in many thousands of yachts.

Legendarily rugged and reliable, the HMG is a fully proportional roll rate (velocity) controller, which combines the proportional precession of a rate gyroscope with the precise control of a variable flapper-jet devise. The HMG utilizes a dynamically balanced rotor mounted in a fully articulated gimble, which is dampened by internal pistons. The rotor operates at turbine speeds, typically 15,000 to 20,000 rpm.

A differential hydraulic pressure signal (not flow) generated by the HMG precisely controls precision servo valves, directing the fins to rotate to the degree required to counteract the vessel's tendency to roll. Due to Pascal's Law, the pressure signal commanded by the HMG is instantaneously received at the fin actuator servo valves. Continuous fin position feedback to the HMG assures that the system provides accurate closed-loop fin position management with no delay or overshoot.