PUBLIC LAW 96-591—DEC. 24, 1980
94 STAT. 3423
quarters situation with another vessel forward of her beam, shall reduce her speed to the minimum at which she can be kept on course. She shall if necessary take all her way off and, in any event, navigate with extreme caution until danger of collision is over. PART C—LIGHTS AND SHAPES RULE 20
Application (a) Rules in this Part shall be complied with in all weathers. 33 USC 2020. (b) The Rules concerning lights shall be complied with from sunset to sunrise, and during such times no other lights shall be exhibited, except such lights as cannot be mistaken for the lights specified in these Rules or do not impair their visibility or distinctive character, or interfere with the keeping of a proper lookout. (c) The lights prescribed by these Rules shall, if carried, also be exhibited from sunrise to sunset in restricted visibility and may be exhibited in all other circumstances when it is deemed necessary. (d) The Rules concerning shapes shall be complied with by day. (e) The lights and shapes specified in these Rules shall comply with the provisions of Annex I of these Rules. RULE 21
Definitions (a) "Masthead light" means a white light placed over the fore and 33 USC 2021. 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, ex;cept that on a vessel of less than 12 meters in length the masthead light shall be placed as nearly as practicable to the fore and aft centerline of the vessel. (b) "Sidelights" mean 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. On a vessel of less than 20 meters in length the side lights may be combined in one lantern carried on the fore and aft centerline of the vessel, except that on a vessel of less than 12 meters in length the sidelights when combined in one lantern shall be placed as nearly as practicable to the fore and aft centerline 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. (g) "Special flashing light" means a yellow light flashing at regular intervals at a frequency of 50 to 70 flashes per minute, placed as far forward and as nearly as practicable on the fore and aft centerline of the tow and showing an unbroken light over an arc of the horizon of
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