Head-on, with a ship to starboard
Three power-driven vessels. Developing level, about 4 min. COLREGs Rules 14, 15 & 16.
The situation
You are under power, heading north. Atlas is coming straight at you on a reciprocal course. Meridian, also power-driven, is crossing from your starboard side and will pass close ahead of Atlas too. All three are in sight of one another in open water.
What do you do?
- Alter boldly to starboard: Pass Atlas port to port and pass astern of Meridian.
- Hold on and let them sort it out: Meridian and Atlas must deal with each other.
- Alter to port, away from Meridian: Open the distance from the crossing ship.
Lookout: Take the pairs one at a time: you and Atlas, you and Meridian, Atlas and Meridian. Board each vessel to see who is on whose starboard side.
Each vessel’s duty
Atlas: Alter to starboard, as you do
You and Atlas meet head-on, so Rule 14 has both of you alter to starboard and pass port to port. Meridian is on Atlas’s port side, so Atlas is also the stand-on vessel towards her.
Meridian: Keep out of Atlas’s way, stand on for you
Atlas is on Meridian’s starboard side, so Meridian gives way to her. You are on Meridian’s port side, so towards you she is the stand-on vessel. Her alteration for Atlas is exactly why you keep watching a stand-on vessel.
Your sound action
Alter boldly to starboard
One bold starboard alteration satisfies both duties: Rule 14 with Atlas, and keeping out of Meridian’s way under Rules 15 and 16 by passing astern of her. Meridian alters to starboard to pass astern of Atlas, so keep watching her: her duty to Atlas changes her course towards you.
Why the other options fall short
Hold on and let them sort it out
You have duties towards both vessels: a head-on situation with Atlas and a crossing with Meridian on your starboard side. Holding on meets neither of them.
Alter to port, away from Meridian
Turning to port puts you across Atlas’s bow just as she turns to starboard for you. In a head-on situation both vessels go to starboard.
Rules 14, 15 & 16 · Head-on and crossing together
Each pair of vessels is judged on its own. Head-on vessels both alter to starboard; in a crossing the vessel with the other on her starboard side gives way. A single vessel can be stand-on towards one ship and give-way towards another.