In the Theory of Operation section, we discussed the gyro’s creation of output torque that is used to counteract the roll of the boat. The equation for this output torque in the Model 7000 Gyro is:
To = wP × L = 2.09 rad/s × 7105 N-m-s = 14,661 N-m
where To = output torque about the gimbal axis (N-m)
wP = output rotation rate or precession rate (rad/s)
L = angular momentum (N-m-s)
As the equation shows, the magnitude of the output torque of the gyro is controlled by the magnitude of the precession rate, wP.
In the Seakeeper Gyro system, the precession rate is actively controlled by a pair of hydraulic cylinders that are commanded by the rate sensors and digital processor in the system. This active control system adjusts the precession rate and therefore the roll restoring force to the degree necessary to optimally eliminate boat roll regardless of the magnitude of the sea state.
Unlike passive control, which must be optimized for a particular level of wave energy, this active control permits the gyro to exert its full power over a range of sea states. A passively controlled gyro must be turned off in the roughest conditions to keep from damaging itself, whereas the Seakeeper Gyro can continue to operate when it is most needed. The Seakeeper Gyro’s processor control also allows for protective auto shut down in event of a fault.
