Masthead & Stern Lights

To avoid collisions, vessels mount navigation lights that permit other vessels to determine the type and relative angle of a vessel, and thus decide if there is a danger of collision.

In general sailing vessels are required to carry a green light that shines on the starboard side a red light on the port side and a white light that shines from astern abaft the beam on both sides.

Power driven vessels, in addition to these lights, must carry either one or two (depending on length) white masthead lights that shine abaft the beam on both sides. If two masthead lights are carried then the after one must be higher than the forward one.

A stern light is a white light placed as nearly as practicable at the stern of the ship showing an unbroken light over an arc of the horizon of 135 degrees and so fixed as to show the light 67.5 degrees from right aft on each side of the vessel.