Night Collision Avoidance with a Crossing Vessel
You are the skipper of a 12 m motor yacht on a coastal passage off the KwaZulu-Natal coast at night. The yacht is steering 045° true at 8 knots. The sea is slight, wind NE 10 knots, visibility good. At 22:00 you observe a steady white light and a green sidelight about 30° on your starboard bow, bearing approximately 075° true. The bearing remains constant over the next 5 minutes. Your radar (if fitted) shows a target at 2.5 nm, closing speed about 12 knots. There are no other vessels in sight. Your vessel is not in any immediate danger of grounding, and there is ample sea room to starboard.
1. What is the risk of collision, and what action should you take as the give-way vessel?
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The bearing of the other vessel is steady at about 075° true, and the range is decreasing (closing speed 12 knots). A steady bearing and decreasing range indicates a risk of collision (COLREGS Rule 7). The other vessel shows a white masthead light and a green sidelight, so it is a power-driven vessel underway, and you see only its starboard side. Therefore, it is crossing from your starboard side, and you are the give-way vessel (Rule 15). You must take early and substantial action to keep well clear (Rule 16). Alter course to starboard and pass astern of the other vessel. A bold alteration of at least 30° to starboard (e.g., to 075° or more) will open the bearing and show your red sidelight to the other vessel, indicating your alteration. Reduce speed if necessary. Avoid altering to port, as this could turn you toward the other vessel. Continue to monitor the bearing until the vessel is past and clear.
2. If the other vessel does not alter course and the risk of collision persists, what should you do?
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If the give-way vessel's action alone is not sufficient, you must take the best action to avoid collision (Rule 17). As the give-way vessel, you should not alter course to port to avoid a vessel crossing from starboard if that vessel is not taking action. You may take a substantial alteration to starboard, or if necessary, reduce speed or stop. If the other vessel is so close that collision cannot be avoided by the give-way vessel alone, you must take the best action to avoid collision, which may include a bold alteration to starboard or a crash stop. In extremis, you may need to take any action, including a turn to port if that is the only way to avoid collision, but only if the situation demands it. Always sound the appropriate whistle signals (Rule 34) to indicate your intentions or doubt.