Tug

A tug is a motorship, which is used to pull other ships (see shipping) in harbours, over the open sea or through rivers and canals.

Tugs are quite stong for their size. Early tugs had been steam engines , today mostly diesel engines are used. They have mostly a high manoeuvrability due to their propulsion units. Instead of a normal propeller, often the so called Schottel[?] propulsion system or the Voith-Schneider[?] propulsion system are used.