Steaming

An informal name for the forward masthead light shown by a power-driven vessel when underway.

The expression “steaming light” is widely used on small craft, particularly for the white light displayed above the sidelights when a sailing vessel is proceeding under engine. In the collision regulations, the defined term is “masthead light,” not “steaming light.”

It should not be confused with an all-round white anchor light. The lights required in any situation depend on the vessel’s type, length and activity, so the applicable regulations and the vessel’s own switching arrangement must be understood.