PURPOSE: To make a gyration angle rate controllable with an automatic steering apparatus, by converting signals from a gyrocompass into gyration angle rate signals as well as controlling the automatic steering apparatus upon comparison with the set value.

CONSTITUTION: Signals from a gyrocompass 11 are to control automatic steering gears 14W21 upon comparison with signals from a course setter 12. Signals of the gyrocompass 11 are further converted into gyration angle rate signals by a signal transducer 22 and compared with those of a gyration angle rate setter 23. Comparative results are regarded as possible to be inputted into automatic steering apparatus 14W21 and when used like this, a helm 21 operates so as to make the ship gyration angle rate constant. If the gyration angle rate is controllable, dredging operations will come still more easier.