The circular motion test technique (CMT) is introduced in this paper, which was developed for the captive maneuverability model test at the Maneuvering Tank of the University of Tokyo. This test makes fully use of the X-Y carriage system at the Maneuvering. Tank. The.X-and Y-carriages are controlled by digital computer along the prescribed circles. The model rotating device which is attached to the Y-carriage controls the direction of a model to keep the drift angle constant. In this way, the CMT technique is completely equivalent to the rotating arm, test. The most important particular of this system is that the very large radius of circle can be get easily in a 30 × 50 m water surface which was practically impossible in the conventional rotating arm test. A trial run of this system was carried out with a 3 m Series 60 model. The obtained results coincide fairly well with the results of Eda and Crane. It can be convinced that the CMT will be a standard captive model test technique in our laboratory after several improvements in the. carriage control and data acquisition systems. The harmonic motion test (HMT) and the transient motion test (TMT) are also going to be developed. HMT and TMT tow a model along the path which corresponds to the sinusoidal velocity and a random path respectively. As the HMT technique is equivalent to the very large amplitude PMM (30 m), it will be possible to get data in between of the conventional rotating arm test and PMM test.