Boat right of way: basic rules for avoiding collisions

The COLREG rules govern head-on situations, crossing and overtaking, but avoiding a collision also requires continuous observation and timely manoeuvres. First identify the type of vessel and the situation, then act clearly and safely.

Keeping a proper lookout comes first

The rules on priority at sea apply alongside the duty to keep a proper lookout by sight and hearing and by using all available means. The person in charge must assess whether there is a risk of collision: if another vessel’s bearing changes very little as the distance closes, there may be a real risk. A memorised rule is no use if you have not seen the other boat in time or are not watching how the situation develops.

The COLREG distinguish between overtaking, head-on situations and crossing, and take account of a vessel’s status: power-driven, sailing, fishing, restricted in its ability to manoeuvre or unable to manoeuvre. When overtaking, the vessel coming up with another must keep clear; in other situations, the conduct required depends on the categories involved and their relative directions. Do not mechanically apply the road rule about ‘the vehicle on the right’ to every meeting at sea.

When a manoeuvre is needed, make it early, substantial and easy for the other vessel to understand. Avoid repeated small course changes that make your intentions unclear. Keep checking the result and maintain a safe speed. In poor visibility, heavy traffic or near channels and ports, take extra care and also follow local rules and the maritime authority’s instructions.

• Keep a continuous lookout and assess whether the bearing changes as the distance closes.
• Identify the type and status of the vessels involved before applying a rule.
• Manoeuvre early and decisively, making a clear change that the other operator can see.
• Keep monitoring until the risk of collision has passed.

An example of a crossing situation

If two power-driven vessels are on crossing courses and there is a risk of collision, the general COLREG rule requires the vessel that sees the other on her starboard side to keep out of the way and, where possible, avoid crossing ahead. The other vessel maintains her course and speed, but must still act if it becomes clear that the vessel required to manoeuvre is not taking appropriate action. Both remain responsible for avoiding a collision.

This example does not automatically apply when a vessel is sailing, fishing, restricted in her ability to manoeuvre, or when other special circumstances apply. Consult the rules and practise with real situations, especially to recognise lights and night-time encounters.

To revise priority rules, navigation lights and maritime rules, use Quiz Patente Ufficiale with study chapters, timed quizzes and a review of mistakes, alongside the official COLREG.