What is a ship without a fixed schedule known as?

A ship without a fixed schedule is commonly referred to as a tramp. Tramp ships operate on an irregular basis, transporting goods based on demand rather than adhering to a predetermined route or timetable. This flexibility allows tramp vessels to engage in voyages that may vary greatly in terms of ports of call and cargo types. They often pick up cargo wherever it is available and deliver it to any suitable port, making them distinct from regular liner services that have set schedules and consistent routes.

In comparison, container ships typically operate on a fixed schedule, moving cargo in standardized containers between designated ports. Bulk carriers are specialized vessels designed to transport bulk cargoes, such as grains or ores, but they usually follow a charter agreement and may have fixed routes depending on the contracts they have in place. Ferries are vessels that carry passengers and vehicles between specific terminals on a regular schedule, which is quite the opposite of the operations of a tramp ship.