The lantern shown at night by a vessel at anchor. International rules of the road require vessels at anchor to carry from sunset to sunrise a single white light forward if under 150 feet in length, and if longer, two such lights, one near the stern and one forward.

White light displayed by ship at anchor. Two such lights are displayed by a ship over 150 feet in length.

a light in the rigging of a ship that is riding at anchor

Parts Anchor Watch Expressions