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—INTERNATIONAL—
Lights and Shapes
RULE 21
Definitions
(a) “Masthead light” means a white light placed over the fore and
aft centerline of the vessel showing an unbroken light over an arc of
the horizon of 225 degrees and so fixed as to show the light from
right ahead to 22.5 degrees abaft the beam on either side of the ves-
sel.
(b) “Sidelights” means a green light on the starboard side and a red
light on the port side each showing an unbroken light over an arc of
the horizon of 112.5 degrees and so fixed as to show the light from
right ahead to 22.5 degrees abaft the beam on its respective side. In
a vessel of less than 20 meters in length the sidelights may be com-
bined in one lantern carried on the fore and aft centerline of the ves-
sel.
(c) “Sternlight” means a white light placed as nearly as practicable
at the stern 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.
(d) “Towing light” means a yellow light having the same character-
istics as the “sternlight” defined in paragraph (c) of this Rule.
(e) “All-round light” means a light showing an unbroken light over
an arc of the horizon of 360 degrees.
(f) “Flashing light” means a light flashing at regular intervals at a
frequency of 120 flashes or more per minute.