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 allround 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. 1
d) I. A power-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 allround 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 centreline 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 centreline 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. 2
Power-driven vessel underway Rule 23 (a) A power-driven vessel underway shall exhibit: Less than 50 metres in length One masthead light (may carry two) Two sidelights A sternlight 50 metres or more in length Two masthead lights Two sidelights A sternlight 3
Power-driven vessel underway Rule 23 (a) Rule 23 (a) Power-driven vessel less than 50 m in length Bow view Underway 4
Power-driven vessel underway Rule 23 (a) Rule 23 (a) Power-driven vessel more or less than 50 m Port side view Underway 5
Power-driven vessel underway Rule 23 (a) By day At night 6
Power-driven vessel underway Rule 23 (a) Rule 23 (a) Power-driven vessel more or less than 50 m Stern view Underway 7
Power-driven vessel underway Rule 23 (a) Power-driven vessel less than 50 metres underway In a power driven vessel of 20 metres or more in lenght the sidelights shall not be placed in front of the forward masthead light (Annex 1 (b)) 8
Power-driven vessel underway Rule 23 (a) In a power-driven vessel of less than 20 metres in length, the sidelights may be placed in front of the masthead light (Annex 3 (b)) 9
Power-driven vessel underway Rule 23 (a) Vessel less than 20m in length (Anex I 3(b)) The sidelights may be placed forward of the masthead light 10
Power-driven vessel less than 20 m Rule 23 (a) Rule 23 (a) Power-driven vessel less than 20 m Underway Bow view With combined lantern Power-driven vessels less than 20 metres may replace their sidelights by a combined lantern 11
Underway Rule 23 (a) A vessel is underway when: She is not at anchor or Made fast to the shore or Aground See Rule 3 (i) 12
Underway Rule 23 (a) A vessel at anchor is not underway 13
Underway Rule 23 (a) A vessel alongside is not underway 14
Underway Rule 23 (a) Vessel underway and making way through the water 15
Underway Rule 23(a) Vessel underway but NOT making way through the water This vessel must show the same lights as if she was making way through the water This vessel may be waiting for a pilot 16
Power-driven vessel underway Rule 23 (a) Advantages of two masthead lights: The course of the vessel can be assessed with some accuracy Through the opening and closing of the lights course alterations can be followed Should the only masthead light go out, the vessel will not be mistaken for a sailing vessel 17
Power-driven vessel underway Rule 23 (a) The bearing of the observed vessel is 045. The opposite bearing is 225. The two masthead lights are close under one another with the forward light slightly to her right (abt. 25 ). Her estimated course is consequently about 250 18
Power-driven vessel underway Rule 23 (a) The two masthead lights of the observed vessel are now far more apart. The course of the observed vessel is thus also further away of the opposite bearing; say abt. 090. The course of the observed vessel is thus about 315. 19
Power-driven vessel underway Rule 2 3(a) When both sidelights are seen simultaneously, the course of the observed vessel is equal to her opposite bearing (up to 006 ) 20
Power-driven vessel underway Rule 23 (a) When both sidelights are seen simultaneously nearly ahead of your own vessel, the observed vessel s course is opposite to your own course (up to 006 ). 21
Power-driven vessel underway Rule 23 (a) The masthead light(s) and the sidelights are visible up to 22,5 abaft the beam. The sternlight is only visible from 22,5 abaft the beam. In practice, they may slightly overlap one another. When an observer is on that limit, the course of the observed vessel can be determined with some degree of accuracy. When the red port light is seen, the course of the observed vessel is equal to her bearing minus 67,5 22
When the green starboard light is seen, the course of the observed vessel is equal to her bearing plus 67,5 23
Air-cushion vessel Rule 23(b) An air-cushion vessel shall exhibit: Same lights as a power-driven vessel, plus An all round flashing yellow light Lower than the masthead lights where it can be most easily seen 24
Air-cushion vessel Air-cushion vessels: Rule 23 (b) Partially afloat or Totally supported by an air-cushion Speeds of up to 80 miles per hour Subject to the wind Silhouette or lights may be different to their course Some make excessive noise and sound signals may not be heard Several types: Hovercrafts Hydrofoils Jetfoils 25
Air-cushion vessel Rule 23 (b) Hovercraft 26
Air-cushion vessel Rule 23 (b) Hydrofoil 27
Air-cushion vessel Rule 23 (b) Jetfoil 28
Rule 23 - Power-driven vessel underway Rule 23 (b) Air-cushion vessel less than 50 m Underway Starboard side view 29
Air-cushion vessel Rule 23 (b) Air-cushion vessel at night 30
Wig craft Rule 23 (c) WIG craft shall exhibit The same lights as a power-driven vessel plus A high intensity all round flashing red light When taking off, landing or in flight near the surface 31
Wig craft Rule 23 (c) 32
Wig craft Rule 23 (c) 33
Wig craft Rule 23 (c) 34
Rule 23 - Power-driven vessel underway Rule 23 (c) Wig craft landing, taking off or flying near the surface 35
Wig craft Rule 23 (c) Wig craft at night 36
Power-driven vessel less than 12 m Rule 23 (d) Power driven vessel of less than 12 metres in length shall exhibit Same lights as larger power-driven vessels OR An all round white light and Sidelights or a combined lantern (Rule 21 (b) The masthead light or all-round white light may be displaced from the fore and aft centreline provided a combined lantern is carried located as nearly as practicable in the same fore and aft line as the masthead light or the all-round white light 37
Power-driven vessel less than 12 m Rule 23 (d) All-round white light Rule 23 (d) (i) Power-driven vessel less than 12 m Underway Bow view With all-round white light With sidelights 38
Power-driven vessel less than 12 m Rule 23 (d) Rule 23 (d) (i) and (iii) Power-driven vessel less than 12 m. Underway With combined lantern Masthead light or all-round white light off centreline Bow view (left) - Stern view (right) 39
Power-driven vessel less than 7 m Rule 23 (d) (ii) A power-driven vessel of less than 7 metres in length, maximum speed of 7 knots shall exhibit: Same lights as larger power-driven vessels or An all round white light and if practicable Sidelights or a combined lantern (Rule 21(c)) 40
Rule 23 - Power-driven vessel underway Rule 23 (d) (ii) Power-driven vessel less than 7 m. Maximum 7 knots Underway. Without sidelights. ANY view 41
Power-driven vessel less than 7 m Rule 23 (d) Rule 23 (d) (ii) Power-driven vessel less than 7 m; max 7 knots Underway Bow view With combined lantern Small power-driven vessels may replace their sidelights by a combined lantern 42