What are the COLREGs?
The International Regulations for Preventing Collisions at Sea are the rules governing how vessels avoid collision. A skipper needs more than isolated mnemonics: the rules work as a system, and the correct action depends on visibility, vessel status, encounter geometry and any special waterway rule.
Always keep a proper lookout, assess risk of collision and act in ample time. A correct label such as “stand-on vessel” does not remove the duty to monitor the situation and take action when the rules require it.
How should vessel responsibilities be applied?
Rule 18 states responsibilities between several vessel types, but it is not a universal ranking that replaces every other steering rule. Subject to Rules 9, 10 and 13, a power-driven vessel must keep out of the way of vessels not under command, restricted in their ability to manoeuvre, engaged in fishing, and sailing.
Narrow channels, traffic separation schemes and overtaking can change which rule controls the encounter. A vessel constrained by her draught also receives particular consideration under Rule 18. Identify the situation before applying a memorised order.
Which steering rules are central?
Rule 12 covers sailing vessels approaching one another. On opposite tacks, the vessel on port tack keeps clear. On the same tack, the windward vessel keeps clear. A port-tack vessel unable to determine the other vessel's tack must keep clear.
Rule 13 covers overtaking. Rules 14 and 15 cover head-on and crossing situations between power-driven vessels. Rules 16 and 17 describe the actions of give-way and stand-on vessels. A stand-on vessel initially keeps course and speed, but that does not mean holding on indefinitely into danger.
Which navigation lights should be recognised?
A power-driven vessel underway normally shows one or more white masthead lights as required by length, red and green sidelights, and a white sternlight. A sailing vessel underway shows sidelights and a sternlight, but does not show a power-driven masthead light unless it is also being propelled by machinery.
Two all-round red lights identify a vessel not under command. Red-white-red identifies a vessel restricted in her ability to manoeuvre. Apply the complete rule, including any additional underway, making-way, towing or length-dependent lights and shapes.
Which sound signals matter most?
In restricted visibility, a power-driven vessel making way sounds one prolonged blast at intervals of not more than two minutes. A power-driven vessel underway but stopped and making no way sounds two prolonged blasts in succession. Several other vessel categories use one prolonged followed by two short blasts.
When power-driven vessels are in sight of one another, one short blast indicates an alteration to starboard, two short blasts indicate port, and three short blasts indicate operation of astern propulsion. At least five short rapid blasts form the doubt signal.
Primary sources
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