Rule 23 — Power-driven Vessel Underway (lights)
Appears on 90% of examsDifficulty 3/552 drill questions
On the paperQ100 / Q30050 questions90% to pass, 5 wrong allowed
Authoritative sources#
Every answer on this topic traces back to the public rule corpus below.
Source excerpts#
33 CFR §83.23
Power-driven vessels underway (Rule 23). (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 meters in length shall not be obliged to exhibit such light but may do so; (iii) Sidelights; and (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 where it can best be seen. (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) A power-driven vessel…
COLREGs 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 meters in length shall not be obliged to exhibit such light but may do so; (iii) sidelights; and (iv) a sternlight. Power-driven vessel underway—50 meters or greater in length. Same for Inland. (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…
COLREGs Rule 23(a)
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 meters in length shall not be obliged to exhibit such light but may do so; (iii) sidelights; and (iv) a sternlight. Power-driven vessel underway—50 meters or greater in length. Same for Inland. Relationship to the Inland Rules: Inland Rule 23 differs from this rule — compare against 33 CFR 83.23 before answering a question that turns on which set applies.
COLREGs Rule 23(b)
Power-driven Vessels Underway (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. Relationship to the Inland Rules: Inland Rule 23 differs from this rule — compare against 33 CFR 83.23 before answering a question that turns on which set applies.
COLREGs Rule 23(c)
Power-driven Vessels Underway (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. Air-cushion vessel when operating in the non-displacement mode—vessel less than 50 meters in length. Same for Inland. Relationship to the Inland Rules: Inland Rule 23 differs from this rule — compare against 33 CFR 83.23 before answering a question that turns on which set applies.
COLREGs Rule 23(d)
Power-driven Vessels Underway (d) (i) A power-driven vessel of less than 12 meters 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 meters 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 meters in length may be displaced from the fore and aft centerline of the vessel if centerline fitting is not practicable, provided that the sidelights are combined in one lantern which shall be carried on the fore and aft centerline of the ves…
Practice this topic#
One real exam question on this topic, cited to source. No sign-up.
Under Annex I to the Inland Navigation Rules, the forward masthead light on a power-driven vessel of 20 meters or more in length must be placed at a minimum height above the hull of how many meters, assuming the vessel's breadth does not exceed 5 meters?
Study this topic#
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The full lesson covers this topic with citation popovers, and there are 52 drill questions behind it.
Drill Rule 23 — Power-driven Vessel Underway (lights) against the real exam.
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