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Rule 24: Towing and pushing
Towing and pushing operations require additional lights/shapes to communicate tow geometry and hazard.
Detailed Explanation
(a) Towing power-driven vessel shows vertical mastheads (2, or 3 if tow >200 m), sidelights, sternlight, towing light above sternlight, and diamond if tow >200 m.
(b) Rigid composite pushing unit is treated as one power-driven vessel (Rule 23).
(c) Pushing ahead/towing alongside (non-composite) shows two vertical mastheads, sidelights and sternlight.
(d) Vessel under (a) or (c) also complies with Rule 23(a)(ii).
(e) Towed vessel/object normally shows sidelights, sternlight, and diamond if tow >200 m.
(f) Group towing/pushing may be lit as one vessel with specified forward/sidelight/stern arrangements.
(g) Inconspicuous/partly submerged tows require additional all-round white lights and diamond(s) by breadth/length.
(h) If prescribed lights/shapes are impracticable, take all possible measures to indicate tow presence/nature.
(i) Distress-assistance towing by non-tug vessel may be exempt from full tug light set, but must indicate relationship, especially by illuminating towline.
Key Points
- Tow >200m: 3 masthead lights + diamond shape by day
- Tow ≤200m: 2 masthead lights, no shape
- Towing light: yellow, above sternlight
- Towed vessel: sidelights + sternlight (+ diamond if >200m)
Examples
- A harbour tug tows a barge with 180 m of towline. She shows two masthead lights in a vertical line, towing light above sternlight, plus sidelights. Under Rule 24(a), two verticals apply because the tow is 200 m or less.
- An ocean-going tug has 250 m of towline to a disabled tanker. She must show three masthead lights vertically and the towed vessel displays a diamond shape by day, per Rule 24(a) for tow exceeding 200 m.
- A pushing vessel and the pushed barge are rigidly connected. They show the lights of a single power-driven vessel per Rule 24(b), treating the composite unit as one.
Common Mistakes
- Forgetting to add the third masthead light when the tow exceeds 200 metres in length.
- Confusing the towing light (yellow, 135-degree arc) with the sternlight (white, 135-degree arc) and mounting only one.
- Not displaying the diamond shape on the towed vessel by day when the tow length exceeds 200 metres.