Objectives This study investigates the motion characteristics of deep-sea vehicles during high-depth vertical transit under vectored propulsion.

Methods Motion equations were established to obtain preliminary solutions for helical diving parameters. Subsequently, steady-state turning diameter, heeling angle, and multi-parameter-influenced powered helical diving tests were conducted on a lake using a vectored-propulsion deep-sea vehicle prototype to analyze diving motion characteristics. Finally, a 3650-meter powered diving test was performed in real-world conditions at 3700-meter depths in the South China Sea.

Results According to the lake trial results, the stable turning diameter of the vector-propelled deep-sea vehicle is only 4 times the total length of the platform, and the turning heel angle is within 2.5°. According to the sea trial results, under the selected control parameters, its average deep-sea diving speed is 0.6 m/s, the standard deviation of the pitch angle is only 0.42°, and the horizontal plane offset during the 3650 m diving process is 442 m. The motion characteristics are stable and controllable, which verifies the feasibility of the powered diving technology using the vector propulsion method for deep-sea vehicles..

Conclusions The results can provide a reference for the research on diving technology of deep-sea vehicles.