COLREGs basics: who gives way

The International Regulations for Preventing Collisions at Sea, the COLREGs, apply in the UK as MSN 1781. The rules never give anyone "right of way": one vessel keeps out of the way (the give-way vessel) and the other stands on. Here are the rules a Day Skipper is expected to know, in plain English.

Every boat, all the time

• Look-out (Rule 5). Keep a proper look-out at all times, by sight, hearing and every means available.
• Risk of collision (Rule 7). If the compass bearing of an approaching vessel doesn't change appreciably, risk of collision exists. It can exist even when the bearing changes, with a very large ship or a tow close by. If in doubt, assume it does.
• Action to avoid collision (Rule 8). Make it positive, early and large enough for the other vessel to see, so you pass at a safe distance. With sea room, a big alteration of course alone is often the best action.

Two sailing boats

Rule 12 decides it by the wind. When the wind is on different sides, the boat with the wind on her port side keeps clear. When it is on the same side, the windward boat keeps clear of the leeward one. The windward side is the side opposite the mainsail. If you are on port tack and can't tell which tack a boat to windward is on, keep clear.

Overtaking, head-on and crossing

• Overtaking (Rule 13). Any vessel overtaking keeps out of the way, sail or power. You are overtaking if you come up from more than 22.5° abaft her beam, where at night you would see only her sternlight. You stay the give-way vessel until you are past and clear. This rule overrides the others: a dinghy overtaking a motor cruiser keeps clear.
• Head-on (Rule 14). Two power-driven vessels meeting head-on each alter course to starboard and pass port to port.
• Crossing (Rule 15). Between two power-driven vessels, the one that has the other on her own starboard side keeps out of the way and avoids crossing ahead.

Who keeps clear of whom

Rule 18 sets an order. A power-driven vessel keeps out of the way of vessels not under command, restricted in their ability to manoeuvre, engaged in fishing, and under sail. A sailing vessel keeps out of the way of vessels not under command, restricted in their ability to manoeuvre and engaged in fishing. Everyone avoids impeding a vessel constrained by her draught. The exceptions are overtaking, narrow channels and traffic separation schemes.

"Engaged in fishing" means with nets, lines or trawls that restrict her manoeuvrability, not a yacht trolling a line. And a yacht under sail with her engine running and driving her is a power-driven vessel.

Narrow channels and shipping lanes

In a narrow channel, keep to the starboard side. A boat under 20 m, or any sailing vessel, must not impede a vessel that can only navigate safely within the channel. In a traffic separation scheme, if you must cross a lane, do it on a heading as nearly as practicable at right angles to the traffic flow.

Give-way and stand-on: what each does

The give-way vessel takes early and substantial action to keep well clear (Rule 16). The stand-on vessel keeps her course and speed (Rule 17). She may act once it is clear the give-way vessel is not doing so, and must act when a collision can't be avoided by the give-way vessel alone.

The full lesson, with a narrated film, restricted visibility (Rule 19) and a quiz, is Module 04: Rules of the road. Lights and sound signals follow in Module 05.