Module 5 - COLREGs
Rule 18 — Responsibilities Between Vessels
Rule 18: quick answer
Rule 18 allocates keep-clear responsibilities between vessel types and operational statuses, but it is not an absolute right-of-way ladder. Establish whether vessels are in sight, whether one is overtaking, and whether narrow-channel or traffic-separation rules apply. Rule 2 and the duties to keep lookout, assess risk and avoid collision still remain.
- Overtaking under Rule 13 takes priority in sighted encounters.
- Rule 19 governs when vessels are not in sight in restricted visibility.
- A sailing vessel propelled by machinery is power-driven for the Rules.
Active recall
Section 6 of 9
Explain the main idea from rule 18 — Responsibilities Between Vessels in your own words.
Rule 18 sets responsibilities between vessel types and statuses. It is a practical guide to who should keep clear in normal sighted encounters, not an absolute right-of-way ladder.
Power-driven and sailing vessels have specific keep-clear duties towards vessels engaged in fishing, vessels not under command (NUC), and vessels restricted in ability to manoeuvre (RAM). A vessel constrained by her draught displays special signals and must navigate with particular caution; other vessels should avoid impeding her where depth, the fairway, or the channel limits her movement. Remember: a sailing vessel using its engine is a power-driven vessel.
Common mistakes
- Calling the Rule 18 responsibilities an unconditional vessel hierarchy.
- Applying sighted give-way rules to vessels detected only by radar in fog.
- Assuming a privileged status removes the duty to avoid collision.
Tip: Use Rule 18 as a decision aid, then keep Rule 2 in mind: both vessels still share responsibility for avoiding collision.
Key points
- Rule 18 sets keep-clear duties by vessel status and manoeuvrability
- Avoid impeding vessels limited by channel, fairway, or draught constraints
- A sailing vessel with engine running is POWER-DRIVEN
- Rule 13 (overtaking) always applies regardless of type
Practice the full encounter sequence
The complete module tests overtaking, crossing, restricted visibility, lights, shapes and responsibilities together.