Definitions.

(a) A steam collier is a vessel mechanically propelled, and specially designed for the carriage of coal in bulk. (b) A towed barge is a vessel without sufficient means of self-propulsion and which requires to be towed. (c) A self-propelled barge is a vessel mechanically propelled of the type specially designed for use in limited coastwise and Great Lakes service and capable of transiting interconnecting canals.