Recently, the heading device using the interference wave measurement of GPS, which is called "GPS compass" or "Satellite compass", was developed as a new application of GPS (Global Positioning System). In this study, two types of GPS compasses were compared with the ring laser gyrocompass (RLG compass) in order to evaluate the heading accuracy of GPS compass. Moreover, the heading ability experiment of GPS compass was performed by comparison with a gyrocompass on a small fishing boat. As a result of these experiments, it was clarified that GPS compass has sufficient heading accuracy equal to the gyrocompass.
