Module 5 - COLREGs
Rule 18 — Responsibilities Between Vessels
What you will learn
Apply Rule 18's vessel-status responsibilities only after checking overtaking, narrow-channel and traffic-separation duties and verifying what the other vessel's signals actually mean.
Rule 18 allocates keep-clear responsibilities between vessel types and operational statuses, but it is not an unconditional hierarchy and it does not grant any vessel an absolute right of way.
Except where Rules 9, 10 and 13 otherwise require, a power-driven vessel underway keeps out of the way of a vessel not under command (NUC), a vessel restricted in ability to manoeuvre (RAM), a vessel engaged in fishing and a sailing vessel. A sailing vessel underway keeps out of the way of NUC, RAM and fishing vessels; a vessel engaged in fishing, so far as possible, keeps out of the way of NUC and RAM.
The status must be real and signalled. 'Engaged in fishing' means fishing with gear that restricts manoeuvrability, not a person angling with trolling lines that do not. RAM arises from the nature of the vessel's work restricting manoeuvre; size or inconvenience alone is not enough. A sailing vessel using propelling machinery is power-driven and by day displays a cone apex down where it can best be seen.
A vessel constrained by her draught may, in addition to normal power-driven signals, exhibit three all-round red lights or a cylinder and must navigate with particular caution. Other vessels should, if circumstances admit, avoid impeding her safe passage. That wording is not the same as an absolute stand-on privilege, and vessels still comply with the other applicable collision rules when risk develops.
Verify the status before assigning responsibility
A yacht sees red-white-red lights ahead near a dredged channel and another small boat showing ordinary sailing lights.
1. Read the signals
Red-white-red identifies RAM; confirm its aspect, movement and any additional lights showing the obstructed side or safe side.
2. Check the waterway rules
Apply any narrow-channel responsibility before assuming Rule 18 alone settles the meeting.
3. Keep clear predictably
Take early action that respects the working vessel's restriction and does not create risk with the sailing boat.
Sense check: The plan must explain why the vessel is RAM and which side is safe, not merely repeat that 'workboats have priority'.
Common mistake or limitation
- A vessel does not become RAM simply because it is large, slow or difficult to turn; the restriction must arise from the nature of its work.
- Running the engine in neutral is not the same wording as using propelling machinery; classify the yacht from how it is actually being propelled and display the required signals.
Recap
- Rule 18 is conditional on more specific Rules 9, 10 and 13.
- Operational status comes from definitions, actual activity and the correct lights or shapes.
- Special protection does not remove collision-avoidance responsibility from either vessel.
Optional quick check
Section 6 of 9
A sailing yacht is using propelling machinery while its sails remain set. How is it treated for the steering rules?
Practice the full encounter sequence
The complete module tests overtaking, crossing, restricted visibility, lights, shapes and responsibilities together.