Rule 23
Power-driven vessels underway
(a) A power-driven vessel underway shall exhibit:
(i) a masthead light forward;
(ii) a second masthead light abaft of and higher than the forward one; except that a vessel of
less than 50 metres in length shall not be obliged to exhibit such light but may do so;
(iii) sidelights;
(iv) a sternlight.
(b) An air-cushion vessel when operating in the non-displacement mode shall, in addition to the
lights prescribed in paragraph (a) of this Rule, exhibit an all-round flashing yellow light.
(c) A WIG craft only when taking off, landing and in flight near the surface shall, in addition to
the lights prescribed in paragraph (a) of this Rule, exhibit a high intensity all-round flashing
red light.
(d) (i) Apower-driven vessel of less than 12 metres in length may in lieu of the lights prescribed
in paragraph (a) of this Rule exhibit an all-round white light and sidelights;
(ii) a power-driven vessel of less than 7 metres in length whose maximum speed does not
exceed 7 knots may in lieu of the lights prescribed in paragraph (a) of this Rule exhibit an
all-round white light and shall, if practicable, also exhibit sidelights;
(iii) the masthead light or all-round white light on a power-driven vessel of less than 12
metres in length may be displaced from the fore and aft centre line of the vessel if
centreline fitting is not practicable, provided that the sidelights are combined in one
lantern which shall be carried on the fore and aft centre line of the vessel or located as
nearly as practicable in the same fore and aft line as the masthead light or the all-round
white light.