Ducted, or Shrouded, Propeller. A propeller rotating within an open-ended cylinder sometimes called a 'Kurt Nozzle". The duct increases significantly the bollard pull of a tug. If the duct and propeller is turned horizontally great manoeuvrability is achieved.
Proper Motion. The actual movement of a heavenly body as distinguished from a parallactic change in its position due to Earth's movement in space. Name is given, also, to Sun's apparent movement in Ecliptic, to distinguish it from his apparent diurnal motion. 2. The movement on a true-motion radar display of the echo of another ship. It shows her course and speed. ('Course Steered and Speed.')