FIELD: methods of determination of speed of motion of submersible vehicles and rotational speed of inboard shaft of twin-shaft birotary power plants. SUBSTANCE: proposed method of indirect determination of speed of motion of submersible vehicle includes recording by submersible hydrophone, for example tape recorder, sonar noise of vehicle underway separating blade frequency and total blade frequency from spectrum of noise and identifying one of them by frequency of rotation of outboard propeller shaft. Rotational speed of inboard propeller shaft is calculated by subtraction of rotational speed of outboard shaft from quotient of total frequency by number of blades of one of propeller shafts. Addition to speed is calculated by excess of rear propeller and direction of excess is determined by measuring list of vehicle when underway. EFFECT: enhanced reliability of measurement of rotational speed of inboard shaft.
