Part C - Lights and Shapes

33 USC 2020 - Application (Rule 20)

(a) Compliance in all weathers
Rules in this Part shall be complied with in all weathers.

(b) Rules concerning lights complied with from sunset to sunrise; other lights
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) Lights during daylight hours in restricted visibility; other circumstances
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) Rules concerning shapes; compliance by day
The Rules concerning shapes shall be complied with by day.

(e) Annex
The lights and shapes specified in these Rules shall comply with the provisions of Annex I of these Rules.

33 USC 2021 - Definitions (Rule 21)

(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.

33 USC 2022 - Visibility of lights (Rule 22)

The lights prescribed in these Rules shall have an intensity as specified in Annex I to these Rules, so as to be visible at the following minimum ranges:

(a) Vessels of 50 meters or more in length
In a vessel 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; and a special flashing light, 2 miles.

(b) Vessels of 12 meters or more but less than 50 meters in length
In a vessel 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; and a special flashing light, 2 miles.

(c) Vessels of less than 12 meters in length
In a vessel of less than 12 meters in length: a masthead light, 2 miles; a sidelight, 1 mile; a sternlight, 2 miles; a towing light, 2 miles; a white, red, green or yellow all-round light, 2 miles; and a special flashing light, 2 miles.

(d) Inconspicuous, partly submerged vessels or objects being towed
In an inconspicuous, partly submerged vessel or object being towed: a white all-round light, 3 miles.

33 USC 2023 - Power-driven vessels underway (Rule 23)

(a) Lights exhibited by power-driven vessels underway
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) Air-cushion vessels
An air-cushion vessel when operating in the nondisplacement 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) Alternative lights for power-driven vessels of less than 12 meters in length
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.

(d) Power-driven vessels when operating on Great Lakes
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.

33 USC 2024 - Towing and pushing (Rule 24)

(a) Power-driven vessels when towing astern
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), 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) Pushing vessel and pushed vessel rigidly connected in composite unit
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.

(c) Power-driven vessel when pushing ahead or towing alongside
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), two masthead lights in a vertical line;

(ii) sidelights; and

(iii) two towing lights in a vertical line.

(d) Compliance with other requirements
A power-driven vessel to which paragraphs (a) or (c) of this Rule apply shall also comply with Rule 23 (a)(i) and 23 (a)(ii).

(e) Vessels being towed
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) Vessels being towed alongside or pushed in a group
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 (iii)

(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; and

(iii) when vessels are towed alongside on both sides of the towing vessels a stern light^[1] 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) Inconspicuous, partly submerged vessel or object being towed
An inconspicuous, partly submerged vessel or object 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 subparagraphs (i) and (ii) 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) Alternative lighting of vessel or object being towed
Where from any sufficient cause it is impracticable for a vessel or object being towed to exhibit the lights 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 the unlighted vessel or object.

(i) Western Rivers or other specified waters; exception
Notwithstanding paragraph (c), on the Western Rivers (except below the Huey P. Long Bridge 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) applies, shall exhibit:

(i) sidelights; and

(ii) two towing lights in a vertical line.

(j) Towing another vessel in distress or otherwise in need of assistance
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 (i) 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 may be used to illuminate the tow.

[1] So in original. Probably should be “sternlight”.

33 USC 2025 - Sailing vessels underway and vessels under oars (Rule 25)

(a) Sailing vessels underway
A sailing vessel underway shall exhibit:

(i) sidelights; and

(ii) a sternlight.

(b) Sailing vessels of less than 20 meters in length
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) Additional lights
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) Sailing vessels of less than 7 meters in length; vessels under oars

(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 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 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) Vessels proceeding under sail
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.

33 USC 2026 - Fishing vessels (Rule 26)

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

(b) Vessels engaged in trawling
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; and

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

(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; and

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

(d) Vessels engaged in fishing in close proximity to other vessels engaged in fishing
The additional signals described in Annex II to these Rules apply to a vessel engaged in fishing in close proximity to other vessels engaged in fishing.

(e) Vessels when not engaged in fishing
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.

33 USC 2027 - Vessels not under command or restricted in their ability to maneuver (Rule 27)

(a) Vessels not under command
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) Vessels restricted in their ability to maneuver
A vessel restricted in her ability to maneuver, except a vessel engaged in mineclearance 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, masthead lights, sidelights and a sternlight, in addition to the lights prescribed in subparagraph (b)(i); and

(iv) when at anchor, in addition to the lights or shapes prescribed in subparagraphs (b)(i) and (ii), the light, lights or shapes prescribed in Rule 30.

(c) Vessels engaged in towing operations
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 subparagraphs (b)(i) and (ii) of this Rule, exhibit the lights or shape prescribed in Rule 24.

(d) Vessels engaged in dredging or underwater operations
A vessel engaged in dredging or underwater operations, when restricted in her ability to maneuver, shall exhibit the lights and shapes prescribed in subparagraphs (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 shape prescribed by this paragraph, instead of the lights or shapes prescribed in Rule 30 for anchored vessels.

(e) Vessels engaged in diving operations
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, 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 insure its all-round visibility.

(f) Vessels engaged in mineclearance operations
A vessel engaged in mineclearance operations shall, in addition to the lights prescribed for a power-driven vessel in Rule 23 or to the lights or shape prescribed for a vessel at anchor in Rule 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 1,000 meters of the mineclearance vessel.

(g) Vessels of less than 12 meters in length
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) Signals of vessels in distress and requiring assistance
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 USC 2028 - [Reserved] (Rule 28)

33 USC 2029 - Pilot vessels (Rule 29)

(a) Vessels engaged on pilotage duty
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 subparagraph (i), the anchor light, lights, or shape prescribed in Rule 30 for anchored vessels.

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

33 USC 2030 - Anchored vessels and vessels aground (Rule 30)

(a) Vessels at anchor
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; and

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

(b) Vessels of less than 50 meters in length; alternative light
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) Illumination of decks
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) Vessels aground
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) Vessels of less than 7 meters in length when at anchor
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) Vessels of less than 12 meters in length when aground
A vessel of less than 12 meters in length when aground shall not be required to exhibit the lights or shapes prescribed in subparagraphs (d)(i) and (ii) of this Rule.

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

33 USC 2031 - Seaplanes (Rule 31)

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