(a) Rules in this subpart (Rules 20-31) (§§ 83.20 through 83.31) shall be complied with in all weathers.

(b) The Rules concerning lights (§§ 83.20 through 83.31) 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 (33 CFR part 84).

(f) A vessel's navigation lights and shapes may be lowered if necessary to pass under a bridge.

(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, except 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 not less than 180 degrees nor more than 225 degrees and so fixed as to show the light from right ahead to abeam and no more than 22.5 degrees abaft the beam on either side of the vessel.

The lights prescribed in these Rules (Subpart C) shall have an intensity as specified in Annex I to these Rules (33 CFR part 84), so as to be visible at the following minimum ranges:

(a) In a vessel of 50 meters or more in length:

(i) A masthead light, 6 miles;

(ii) A sidelight, 3 miles;

(iii) A sternlight, 3 miles;

(iv) A towing light, 3 miles;

(v) A white, red, green or yellow all-round light, 3 miles; and

(vi) A special flashing light, 2 miles.

(b) In a vessel of 12 meters or more in length but less than 50 meters in length:

(i) A masthead light, 5 miles; except that where the length of the vessel is less than 20 meters, 3 miles;

(ii) A sidelight, 2 miles;

(iii) A sternlight, 2 miles;

(iv) A towing light, 2 miles;

(v) A white, red, green or yellow all-round light, 2 miles; and

(vi) A special flashing light, 2 miles.

(c) In a vessel of less than 12 meters in length:

(i) A masthead light, 2 miles;

(ii) A sidelight, 1 mile;

(iii) A sternlight, 2 miles;

(iv) A towing light, 2 miles;

(v) A white, red, green or yellow all-round light, 2 miles; and

(vi) A special flashing light, 2 miles.

(d) In an inconspicuous, partly submerged vessel or objects being towed:

(i) A white all-round light, 3 miles.

(ii) [Reserved]

(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 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.

(e) A power-driven vessel when operating on the Great Lakes may carry an all-round white light in lieu of the second masthead light and sternlight prescribed in paragraph (a) of this Rule. The light shall be carried in the position of the second masthead light and be visible at the same minimum range.

(a) A power-driven vessel when towing astern shall exhibit:

(i) Instead of the light prescribed either in Rule 23(a)(i) or 23(a)(ii) (§§ 83.23(a)(i) and (ii)), two masthead lights in a vertical line. When the length of the tow, measuring from the stern of the towing vessel to the after end of the tow exceeds 200 meters, three such lights in a vertical line;

(ii) Sidelights;

(iii) A sternlight;

(iv) A towing light in a vertical line above the sternlight; and

(v) When the length of the tow exceeds 200 meters, a diamond shape where it can best be seen.

(b) When a pushing vessel and a vessel being pushed ahead are rigidly connected in a composite unit they shall be regarded as a power-driven vessel and exhibit the lights prescribed in Rule 23 (§ 83.23).

(c) A power-driven vessel when pushing ahead or towing alongside, except as required by paragraphs (b) and (i) of this Rule, shall exhibit:

(i) Instead of the light prescribed either in Rule 23(a)(i) or 23(a)(ii) (§ 83.23(a)(i) or (ii)), two masthead lights in a vertical line;

(ii) Sidelights; and

(iii) Two towing lights in a vertical line.

(d) A power-driven vessel to which paragraphs (a) or (c) of this Rule applies shall also comply with Rule 23(a) (i) and 23(a)(ii)(§ 83.23(a)(i) or (ii)).

(e) A vessel or object other than those referred to in paragraph (g) of this Rule being towed shall exhibit:

(i) Sidelights;

(ii) A sternlight; and

(iii) When the length of the tow exceeds 200 meters, a diamond shape where it can best be seen.

(f) Provided that any number of vessels being towed alongside or pushed in a group shall be lighted as one vessel, except as provided in paragraph (f)(iii) of this Rule.

(i) A vessel being pushed ahead, not being part of a composite unit, shall exhibit at the forward end, sidelights and a special flashing light.

(ii) A vessel being towed alongside shall exhibit a sternlight and at the forward end, sidelights and a special flashing light.

(iii) When vessels are towed alongside on both sides of the towing vessel, a sternlight shall be exhibited on the stern of the outboard vessel on each side of the towing vessel, and a single set of sidelights as far forward and as far outboard as is practicable, and a single special flashing light.

(g) An inconspicuous, partly submerged vessel or object, or combination of such vessels or objects being towed, shall exhibit:

(i) If it is less than 25 meters in breadth, one all-round white light at or near each end;

(ii) If it is 25 meters or more in breadth, four all-round white lights to mark its length and breadth;

(iii) If it exceeds 100 meters in length, additional all-round white lights between the lights prescribed in paragraphs (g)(i) and (ii) of this Rule so that the distance between the lights shall not exceed 100 meters: provided, that any vessels or objects being towed alongside each other shall be lighted as one vessel or object;

(iv) A diamond shape at or near the aftermost extremity of the last vessel or object being towed; and

(v) The towing vessel may direct a searchlight in the direction of the tow to indicate its presence to an approaching vessel.

(h) Where from any sufficient cause it is impracticable for a vessel or object being towed to exhibit the lights or shapes prescribed in paragraph (e) or (g) of this Rule, all possible measures shall be taken to light the vessel or object towed or at least to indicate the presence of such vessel or object.

(i) Where from any sufficient cause it is impracticable for a vessel not normally engaged in towing operations to display the lights prescribed by paragraph (a), (c), or (j) of this Rule, such vessel shall not be required to exhibit those lights when engaged in towing another vessel in distress or otherwise in need of assistance. All possible measures shall be taken to indicate the nature of the relationship between the towing vessel and the vessel being assisted. The searchlight authorized by Rule 36 (§ 83.36) may be used to illuminate the tow.

(j) Notwithstanding paragraph (c) of this Rule, on the Western Rivers (except below the Huey P. Long Bridge at mile 106.1 Above Head of Passes on the Mississippi River) and on waters specified by the Secretary, a power-driven vessel when pushing ahead or towing alongside, except as paragraph (b) of this Rule applies, shall exhibit:

(i) Sidelights; and

(ii) Two towing lights in a vertical line.

(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 length shall, if practicable, exhibit the lights prescribed in paragraph (a) or (b) of this Rule, but if she does not, she shall exhibit an all-round white light or have ready at hand an electric torch or lighted lantern showing a white light which shall be exhibited in sufficient time to prevent collision.

(ii) A vessel under oars may exhibit the lights prescribed in this Rule for sailing vessels, but if she does not, she shall exhibit an all-round white light or have ready at hand an electric torch or lighted lantern showing a white light which shall be exhibited in sufficient time to prevent collision.

(e) A vessel proceeding under sail when also being propelled by machinery shall exhibit forward, where it can best be seen, a conical shape, apex downward. A vessel of less than 12 meters in length is not required to exhibit this shape, but may do so.

(a) A vessel engaged in fishing, whether underway or at anchor, shall exhibit only the lights and shapes prescribed in this Rule.

(b) A vessel when engaged in trawling, by which is meant the dragging through the water of a dredge net or other apparatus used as a fishing appliance, shall exhibit:

(i) Two all-round lights in a vertical line, the upper being green and the lower white, or a shape consisting of two cones with their apexes together in a vertical line one above the other;

(ii) A masthead light abaft of and higher than the all-round green light; a vessel of less than 50 meters in length shall not be obliged to exhibit such a light but may do so;

(iii) When making way through the water, in addition to the lights prescribed in this paragraph, sidelights and a sternlight.

(c) A vessel engaged in fishing, other than trawling, shall exhibit:

(i) Two all-round lights in a vertical line, the upper being red and the lower white, or a shape consisting of two cones with apexes together in a vertical line one above the other;

(ii) When there is outlying gear extending more than 150 meters horizontally from the vessel, an all-round white light or a cone apex upward in the direction of the gear;

(iii) When making way through the water, in addition to the lights prescribed in this paragraph, sidelights and a sternlight.

(d) [Reserved]

(e) A vessel when not engaged in fishing shall not exhibit the lights or shapes prescribed in this Rule, but only those prescribed for a vessel of her length.

(f) Additional signals for fishing vessels fishing in close proximity:

(i) The lights mentioned herein shall be placed where they can best be seen. They shall be at least 0.9 meters apart but at a lower level than lights prescribed in this Rule. The lights shall be visible all round the horizon at a distance of at least 1 mile but at a lesser distance from the lights prescribed by paragraphs (a) through (c) of this Rule for fishing vessels.

(ii) Signals for trawlers.

(1) Vessels when engaged in trawling, whether using demersal or pelagic gear, may exhibit:

(A) When shooting their nets: Two white lights in a vertical line;

(B) When hauling their nets: One white light over one red light in a vertical line;

(C) When a net has come fast upon an obstruction: Two red lights in a vertical line.

(2) Each vessel engaged in pair trawling may exhibit:

(A) By night, a searchlight directed forward and in the direction of the other vessel of the pair;

(B) When shooting or hauling their nets or when their nets have come fast upon an obstruction, the lights prescribed in paragraph (f)(ii)(1) of this Rule.

(iii) Signals for purse seiners.

(1) Vessels engaged in fishing with purse seine gear may exhibit two yellow lights in a vertical line. These lights shall flash alternately every second and with equal light and occultation duration. These lights may be exhibited only when the vessel is hampered by its fishing gear.

(2) [Reserved]

(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).

(a) A vessel engaged on pilotage duty shall exhibit:

(i) At or near the masthead, two all-round lights in a vertical line, the upper being white and the lower red;

(ii) When underway, in addition, sidelights and a sternlight; and

(iii) When at anchor, in addition to the lights prescribed in paragraph (i) of this Rule, the anchor light, lights, or shape prescribed in Rule 30 (§ 83.30) for vessels at anchor.

(b) A pilot vessel when not engaged on pilotage duty shall exhibit the lights or shapes prescribed for a vessel of her length.

(a) A vessel at anchor shall exhibit where it can best be seen:

(i) In the fore part, an all-round white light or one ball;

(ii) At or near the stern and at a lower level than the light prescribed in paragraph (i) of this Rule, an all-round white light.

(b) A vessel of less than 50 meters in length may exhibit an all-round white light where it can best be seen instead of the lights prescribed in paragraph (a) of this Rule.

(c) A vessel at anchor may, and a vessel of 100 meters or more in length shall, also use the available working or equivalent lights to illuminate her decks.

(d) A vessel aground shall exhibit the lights prescribed in paragraph (a) or (b) of this Rule and in addition, if practicable, where they can best be seen:

(i) Two all-round red lights in a vertical line; and

(ii) Three balls in a vertical line.

(e) A vessel of less than 7 meters in length, when at anchor, not in or near a narrow channel, fairway, anchorage, or where other vessels normally navigate, shall not be required to exhibit the lights or shape prescribed in paragraphs (a) and (b) of this Rule.

(f) A vessel of less than 12 meters in length when aground shall not be required to exhibit the lights or shapes prescribed in paragraphs (d)(i) and (ii) of this Rule.

(g) A vessel of less than 20 meters in length, when at anchor in a special anchorage area designated by the Coast Guard, shall not be required to exhibit the anchor lights and shapes required by this Rule.

(h) The following barges shall display at night and if practicable in periods of restricted visibility the lights described in paragraph (i) of this Rule:

(i) Every barge projecting into a buoyed or restricted channel.

(ii) Every barge so moored that it reduces the available navigable width of any channel to less than 80 meters.

(iii) Barges moored in groups more than two barges wide or to a maximum width of over 25 meters.

(iv) Every barge not moored parallel to the bank or dock.

(i) Barges described in paragraph (h) of this Rule shall carry two unobstructed all-round white lights of an intensity to be visible for at least 1 nautical mile and meeting the technical requirements as prescribed in Annex I (33 CFR part 84).

(j) A barge or group of barges at anchor or made fast to one or more mooring buoys or other similar device, in lieu of the provisions of this Rule, may carry unobstructed all-round white lights of an intensity to be visible for at least 1 nautical mile that meet the requirements of Annex I (33 CFR part 84) and shall be arranged as follows:

(i) Any barge that projects from a group formation, shall be lighted on its outboard corners.

(ii) On a single barge moored in water where other vessels normally navigate on both sides of the barge, lights shall be placed to mark the corner extremities of the barge.

(iii) On barges moored in group formation, moored in water where other vessels normally navigate on both sides of the group, lights shall be placed to mark the corner extremities of the group.

(k) The following are exempt from the requirements of this Rule:

(i) A barge or group of barges moored in a slip or slough used primarily for mooring purposes.

(ii) A barge or group of barges moored behind a pierhead.

(iii) A barge less than 20 meters in length when moored in a special anchorage area designated in accordance with § 109.10 of this chapter.

(l) Barges moored in well-illuminated areas are exempt from the lighting requirements of this Rule. These areas are as follows:

Where it is impracticable for a seaplane or a WIG craft to exhibit lights and shapes of the characteristics or in the positions prescribed in the Rules of this subpart, she shall exhibit lights and shapes as closely similar in characteristics and position as is possible.