Abstract: A system for precise positioning of subsea units has a remotely operated vehicle, an inertial measurement unit positioned on the vehicle so as to produce a signal relative to a position of the subsea unit, a doppler velocity log coupled to the vehicle in producing a signal relative to the position of the subsea unit, a baseline measurement device coupled to the vehicle and producing a signal relative to the position of the subsea unit, a Kalman filter cooperative with the signals from the inertial measurement unit and the doppler velocity log and the baseline measurement device, and a processor cooperative with the Kalman filter for producing an output indicative of the positioning of the subsea unit. A doppler velocity log includes a plurality of beams which are individually connected to the Kalman Filter.