Tractor Tug

Tug with the propulsion units placed forward of midship — either Voith-Schneider cycloidal propellers or azimuth thrusters — so the tug operates with its towing point aft of the propellers rather than ahead of them. The arrangement eliminates the risk of girting (capsize when the towline pulls athwartships against the tug) that plagued conventional screw tugs, allowing the tug to apply transverse force at the stern of an assisted vessel safely. Tractor tugs are common in pilotage areas with confined waters and in escort work for laden tankers.