Yard tug bollard pull

Yard tug bollard pull is the static pulling force a harbor or shipyard tug develops at zero speed, measured in tonnes against a fixed bollard with the line through a load cell. It is the standard rating of a tug’s towing capability and sets which tug is adequate to assist or move a given ship in port. Bollard pull comes from propeller thrust, so ducted (Kort nozzle) propellers and azimuth or Voith drives raise it for a given power; a rough guide is about 1 tonne of bollard pull per 100 kW of installed power, varied by propeller type. It is the converse of free-running speed, where thrust is lowest.