The term 'PORT WORK BOAT' is a job description for a TUG, which is a three-letter word. A TUG is a type of vessel that is used to maneuver larger ships in and out of ports, as well as to assist in other operations such as towing barges and other vessels. Tugs are typically powered by diesel engines and are designed to be highly maneuverable. They are also equipped with powerful winches and tow lines to help them perform their duties.