Section 83.27 - Vessels not under command or restricted in their ability to maneuver (Rule 27)(a) A vessel not under command shall exhibit: (i) Two all-round red lights in a vertical line where they can best be seen;(ii) Two balls or similar shapes in a vertical line where they can best be seen; and(iii) When making way through the water, in addition to the lights prescribed in this paragraph, sidelights and a sternlight.(b) A vessel restricted in her ability to maneuver, except a vessel engaged in mine clearance operations, shall exhibit:(i) Three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white;(ii) Three shapes in a vertical line where they can best be seen. The highest and lowest of these shapes shall be balls and the middle one a diamond;(iii) When making way through the water, a masthead light or lights, sidelights and a sternlight, in addition to the lights prescribed in paragraph (b)(i) of this Rule; and(iv) When at anchor, in addition to the lights or shapes prescribed in paragraphs (b)(i) and (ii) of this Rule, the light, lights or shapes prescribed in Rule 30 (§ 83.30 ).(c) A vessel engaged in a towing operation which severely restricts the towing vessel and her tow in their ability to deviate from their course shall, in addition to the lights or shapes prescribed in paragraphs (b)(i) and (ii) of this Rule, exhibit the lights or shapes prescribed in Rule 24 (§ 83.24 ).(d) A vessel engaged in dredging or underwater operations, when restricted in her ability to maneuver, shall exhibit the lights and shapes prescribed in paragraphs (b)(i), (ii), and (iii) of this Rule and shall in addition, when an obstruction exists, exhibit: (i) Two all-round red lights or two balls in a vertical line to indicate the side on which the obstruction exists;(ii) Two all-round green lights or two diamonds in a vertical line to indicate the side on which another vessel may pass; and(iii) When at anchor, the lights or shapes prescribed by this paragraph, instead of the lights or shape prescribed in Rule 30 (§ 83.30 ).(iv) Dredge pipelines that are floating or supported on trestles shall display the following lights at night and in periods of restricted visibility.(1) One row of yellow lights. The lights must be:(A) Flashing 50 to 70 times per minute,(B) Visible all round the horizon,(C) Visible for at least 2 miles,(D) Not less than 1 and not more than 3.5 meters above the water,(E) Approximately equally spaced, and(F) Not more than 10 meters apart where the pipeline crosses a navigable channel. Where the pipeline does not cross a navigable channel the lights must be sufficient in number to clearly show the pipeline's length and course.(2) Two red lights at each end of the pipeline, including the ends in a channel where the pipeline is separated to allow vessels to pass (whether open or closed). The lights must be: (A) Visible all round the horizon, and(B) Visible for at least 2 miles, and(C) One meter apart in a vertical line with the lower light at the same height above the water as the flashing yellow light.(e) Whenever the size of a vessel engaged in diving operations makes it impracticable to exhibit all lights and shapes prescribed in paragraph (d) of this Rule, as appropriate, the following shall instead be exhibited:(i) Three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white;(ii) A rigid replica of the International Code flag "A" not less than 1 meter in height. Measures shall be taken to ensure its all-round visibility.(f) A vessel engaged in mine clearance operations shall, in addition to the lights prescribed for a power-driven vessel in Rule 23 (§ 83.23 ) or to the lights or shape prescribed for a vessel at anchor in Rule 30 (§ 83.30 ), as appropriate, exhibit three all-round green lights or three balls. One of these lights or shapes shall be exhibited near the foremast head and one at each end of the fore yard. These lights or shapes indicate that it is dangerous for another vessel to approach within 1000 meters of the mine clearance vessel.(g) A vessel of less than 12 meters in length, except when engaged in diving operations, is not required to exhibit the lights or shapes prescribed in this Rule.(h) The signals prescribed in this Rule are not signals of vessels in distress and requiring assistance. Such signals are contained in Annex IV to these Rules ( 33 CFR part 87 ).USCG-2012-0102, 79 FR 37912 , July 2, 2014, as amended by USCG-2012-0102, 79 FR 68622 , Nov. 18, 2014; USCG-2018-0874, 84 FR 30878 , June 28, 2019 USCG-2018-0874, 84 FR 30878, 6/28/2019