Exam frequency
65%
Difficulty
3/5
Drill questions
68
Authoritative sources
Every answer on this topic traces back to the public rule corpus below.
Source excerpts
33 CFR §83.23
§ 83.23 § 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 pow…
33 CFR §83.25
§ 83.25 § 83.25 Sailing vessels underway and vessels under oars (Rule 25). (a) A sailing vessel underway shall exhibit: (i) Sidelights; and (ii) A sternlight. (b) In a sailing vessel of less than 20 meters in length the lights prescribed in paragraph (a) of this Rule may be combined in one lantern carried at or near the top of the mast where it can best be seen. (c) A sailing vessel underway may, in addition to the lights prescribed in paragraph (a) of this Rule, exhibit at or near the top of the mast, where they can best be seen, two all-round lights in a vertical line, the upper being red and the lower green, but these lights shall not be exhibited in conjunction with the combined lantern permitted by paragraph (b) of this Rule. (d)(i) A sailing vessel of less than 7 meters in leng…
33 CFR §84.02
§ 84.02 § 84.02 Vertical positioning and spacing of lights. (a) On a power-driven vessel of 20 meters or more in length the masthead lights shall be placed as follows: (i) The forward masthead light, or if only one masthead light is carried, then that light, at a height above the hull of not less than 5 meters, and, if the breadth of the vessel exceeds 5 meters, then at a height above the hull not less than such breadth, so however that the light need not be placed at a greater height above the hull than 8 meters. (ii) When two masthead lights are carried the after one shall be at least 2 meters vertically higher than the forward one. (b) The vertical separation of the masthead lights of power-driven vessels shall be such that in all normal conditions of trim the after light will be se…
COLREGs Rule 21
COLREGs 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 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 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 combined in one lantern carried on the fore and aft centerline of the vessel. (c) “Sternlight” means a white light placed as nearly as practicable at the …
COLREGs Rule 22
COLREGs Rule 22 — Visibility of Lights The lights prescribed in these Rules shall have an intensity as specified in Section 8 of Annex I to these Regulations so as to be visible at the following minimum ranges: (a) In vessels of 50 meters or more in length: − a masthead light, 6 miles; − a sidelight, 3 miles; − a sternlight, 3 miles; − a towing light, 3 miles; − a white, red, green or yellow all-round light, 3 miles. (b) In vessels of 12 meters or more in length but less than 50 meters in length: − a masthead light, 5 miles; except that where the length of the vessel is less than 20 meters, 3 miles; − a sidelight, 2 miles; − a sternlight, 2 miles; − a towing light, 2 miles; − a white, red, green or yellow all-round light, 2 miles. (c) In vessels of less than 12 meters in length: − a masth…
COLREGs Rule 23
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. 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.
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A sailing vessel underway optionally exhibits two all-round lights in a vertical line at or near the top of the mast. What is the correct color arrangement of these lights?
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