Tug, for one, is a type of BOAT used for towing or pushing other vessels. It is typically smaller than the vessel it is towing and is powered by either diesel or steam engines. Tugs are commonly used in ports and harbors to move ships and barges, as well as to assist in maneuvering larger vessels in tight spaces. They are also used in rivers and canals to tow barges and other vessels. In addition, tugs are used in offshore oil and gas operations to move rigs and other equipment.