COLREGs · Rule 24 · 33 CFR §83.24

Towing and Pushing

As of 2026-06-25, Rule 24 is the towing-lights rule: towing astern uses two masthead lights, but a tow over 200 m requires three masthead lights and a diamond; pushing ahead or towing alongside uses a different two-towing-light pattern, with a special Inland Western Rivers exception.

What does Rule 24 actually say?#

Source

Verbatim 33 CFR §83.24, public domain. The international COLREGs text is published by the IMO and cannot be reproduced here; this U.S. wording tracks it closely.

A power-driven vessel when towing astern shall exhibit:

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;

Sidelights;

A sternlight;

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

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

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).

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

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;

Sidelights; and

Two towing lights in a vertical line.

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)).

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

Sidelights;

A sternlight; and

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

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.

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

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

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.

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

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

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

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;

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

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

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.

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.

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:

Sidelights; and

Two towing lights in a vertical line. [USCG-2012-0102, 79 FR 37912, July 2, 2014, as amended by USCG-2012-0102, 79 FR 68622, Nov. 18, 2014; USCG-2015-0433, 80 FR 44280, July 27, 2015; USCG-2016-0498, 82 FR 35080, July 28, 2017; USCG-2018-0874, 84 FR 30878, June 28, 2019]

Practice this rule#

One real exam question on this rule, cited to source. No sign-up.

Rule 24 — Towing and Pushing (lights)

A towing light, as defined in the Inland Navigation Rules, is best described as which of the following?

How does Inland Rule 24 differ from COLREGs?#

Inland Rule 24 has special provisions for composite units and for Western Rivers pushing-ahead or towing-alongside vessels, where the vessel shows sidelights and two towing lights in a vertical line.

21 of 38 rules differ somewhere; the five the exam leans on are Rule 9, Rule 10, Rule 24, Rule 28 and Rule 34, side by side on Inland vs International Rules.

Why it shows up on the exam#

The exam trap is sorting the towing case before counting lights: tow astern, push ahead, tow alongside, composite unit, and Western Rivers are different answers.

What does the exam actually test here?#

Tow astern
>200 m = 3 mastheads + diamond
A power-driven vessel towing astern shows two masthead lights in a vertical line instead of the normal Rule 23 masthead light. If the tow exceeds 200 meters, it shows three masthead lights and a diamond shape, plus sidelights, sternlight, and a yellow towing light above the sternlight (33 CFR §83.24(a)).
Push or alongside
2 mastheads + 2 towing lights
When pushing ahead or towing alongside, the towing vessel shows two masthead lights in a vertical line, sidelights, and two yellow towing lights in a vertical line unless the composite-unit or Inland Western Rivers rule changes the answer (§83.24(c), (j)).
Composite unit
Treat as one power-driven vessel
If the pushing vessel and the vessel being pushed are rigidly connected as a composite unit, Rule 24 sends you back to Rule 23: the unit is treated as a power-driven vessel, not as a towing display (§83.24(b)).

Rule 24 — common exam questions#

What is Rule 24 in COLREGs?

Rule 24 covers the lights and day shapes for towing and pushing. It separates towing astern, pushing ahead, towing alongside, composite units, towed objects, and special Inland Western Rivers cases.

When does a tow need three masthead lights and a diamond shape?

A power-driven vessel towing astern needs three masthead lights in a vertical line, and the tow needs a diamond shape, when the length of the tow from the towing vessel's stern to the after end of the tow exceeds 200 meters.

How is a composite unit different from a tow under Rule 24?

A rigidly connected pushing vessel and pushed vessel are treated as a single power-driven vessel, so they show the Rule 23 lights rather than the ordinary Rule 24 towing or pushing display.

What is the Inland Western Rivers exception in Rule 24?

On the Western Rivers, except below the Huey P. Long Bridge on the Mississippi River, an Inland pushing-ahead or towing-alongside vessel shows sidelights and two towing lights in a vertical line instead of the standard Rule 24(c) masthead-light pattern.

Authoritative source#

33 CFR §83.24 — this section with its neighbours. 33 CFR Part 83 is public domain; checked 2026-06-25.
COLREGs Rule 24 is published by the IMO and is authoritative internationally.

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