Abstract: A system for obtaining torque and angular velocity of a load transmitting shaft (such as for example the power drive shaft in a marine propulsion system) and adapted to obtain the efficiency and power output of the shaft. The system makes use of a matched pair of optoelectronic sensors, each comprising a pair of light sources, a pair of optoelectronic pick-ups and a relatively rotating interrupter member. The pair of optoelectronic sensors permits an accurate measurement of the relative angular displacement of the relatively rotating members. The system converts a binary-type optical message into electrical pulse signals which are processed to provide readings of torque, angular velocity, power output and shaft efficiency. The optoelectronic sensors are positionally adjustable by means of set screws, and the system can be calibrated by means of self-test circuits. The optical pick-up includes a vertical array of individual optical fibers.