All power-driven vessels are required to carry white,
red, and green running lights when under way.
(See figure 21.) Running lights consist of a white
masthead light in the forward part of the ship (a second
masthead light, abaft and higher than the forward one,
is required on vessels 50 meters or more in length),
sidelights (red on the portside, green on the starboard
side), and a white stern light.
Running lights are fixed so they display an
unbroken arc of light over certain portions of the
horizon, making them readily identifiable. Running
lights and their degree of arc are as follows:
Degree of Arc
Figure 21.Running lights.