A Tow Tug is a tug boat used to tow a barge. It may also be used as an anchor handling tug by a derrick or lay barge. In harbors and restricted sailing areas, ships are usually assisted by one or more tugboats. The ship and the tugboat are firstly connected by cable. The tugboat sails with the ship and positions itself in such a manner that it can tow the ship in a specific direction by means of the towing cable. During these manoeuvres, it is also possible for a tugboat to be manoeuvred against the ship in order to be able to push it.