Power Take-Off / Take-In (PTO/PTI)

PTO and PTI describe a shaft machine that can run as a generator or a motor on the main propulsion shaft. In PTO mode the main engine drives a shaft generator that supplies the ship’s electrical load, retiring the auxiliary gensets and burning the main engine’s cheaper, more efficient fuel per kWh. In PTI mode the same machine motors the shaft, taking electrical power to boost propulsion or to give take-me-home redundancy if the main engine fails. PTO and PTI are the core of shaft-generator hybrid arrangements and cut fuel and emissions by shifting electrical generation onto the most efficient prime mover.