Seaman's Handbook
PART C. Lights and Shapes : Definitions
(a) "Masthead light" means a white light placed over the fore and aft centre line 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 vessel.(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 degree 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 metres in length the sidelights may be combined in one lantern carried on the
fore and aft centreline of the vessel.(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 characteristics 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.
