A Tramp line is an ocean carrier company operating vessels (Tramp steamers or Trampers) not on regular runs or schedules. They call at any port where cargo may be available. They are available to charter in several ways:
Trampers are a descendant of the early merchant ships whose masters (who were also their owners) loaded them with cargo at home to sell abroad, and vice versa. Depending on the size of the vessel, they are also classified as Seaway or Handy, Panamax, Suezmax and Cape, indicating the type of routes they are likely to take, carrying mainly loose grain, coal and other mineral ores in holds below deck.
- Clarkson Research Studies The Tramp Shipping Market  Accessed July 12, 2007
- U.S. Department of Transportation Maritime Administration
- Traveling by Tramp Steamer Maris.com Accessed July 13, 2007