Official rule text as published in the U.S. Coast Guard Navigation Rules
Except where Rules 9, 10, and 13 otherwise require:
(a) A power-driven vessel underway shall keep out of the way of: (i) a vessel not under command; (ii) a vessel restricted in her ability to maneuver; (iii) a vessel engaged in fishing; (iv) a sailing vessel.
(b) A sailing vessel underway shall keep out of the way of: (i) a vessel not under command; (ii) a vessel restricted in her ability to maneuver; (iii) a vessel engaged in fishing.
(c) A vessel engaged in fishing when underway shall, so far as possible, keep out of the way of: (i) a vessel not under command; (ii) a vessel restricted in her ability to maneuver.
MyCOLREGS explanation
Summary
Rule 18 ranks vessel categories into a pecking order, from most protected to least:
- Not under command
- Restricted in her ability to maneuver
- Engaged in fishing
- Sailing (port tack givesway to starboard)
- Sailing (windward givesway to leeward)
- Power (port boat givesway to starboard)
- Power (head-on: both boats turn to starboard)
- Vessel under oars
Each category keeps clear of every category above it — power-driven vessels keep clear of every category above it, etc. It is a chain of duties, not a single rule. Adding in other rules the pecking order becomes:
- Rules 9, 10: Narrow-channel, traffic-separation obligations
- Rule 13: Overtaking must give way to being overtaken
- Rules 2, 12, 14, 15, 18: Vessel-category hierarchy (above)
Real World Example
The hierarchy exists because maneuverability, not size or courtesy, is what Rule 18 actually ranks - a category earns deference by being physically unable to get out of the way, not by being important. That baseline is also conditional from the first word: Rules 9, 10, and 13 can override it entirely before you even get to ranking anyone. And the line isn't about whether fish are involved: a charter boat trolling four lines can drop everything and turn in seconds, while a trawler with her net down cannot, no matter how much her captain wants to.
Practice Questions
Q1. A power-driven vessel, a sailing vessel, and a fishing vessel actively engaged in fishing are all approaching the same patch of water with risk of collision among each pair. Under the basic Rule 18 hierarchy, which vessel sits at the bottom, keeping clear of the other two?
A. The fishing vessel.
B. Whichever vessel is largest.
C. The sailing vessel.
D. The power-driven vessel.
Q2. A center-console recreational boat has two rods trolling lines behind it and can accelerate, stop, or turn freely at any moment. Under Rule 18, does this boat qualify as "a vessel engaged in fishing" entitled to have others keep clear?
A. No - her gear does not restrict her maneuverability, so she does not have that status.
B. Yes, but only if she is anchored.
C. No boat under 20 meters can ever be a fishing vessel under the Rules.
D. Yes - any boat with a fishing line in the water counts.
Practice Question Answers
Q1.
D. The power-driven vessel. Rule 18(a) puts the power-driven vessel at the bottom of the basic hierarchy: she keeps out of the way of vessels not under command, restricted vessels, fishing vessels, and sailing vessels. A names a vessel that sits ABOVE power-driven in the hierarchy - the fishing vessel is one the power-driven vessel gives way to, not the other way around. B substitutes vessel size for category. C also names a vessel power-driven gives way to, not the one at the bottom.
Q2.
A. No - her gear does not restrict her maneuverability, so she does not have that status. Rule 3(d) defines "vessel engaged in fishing" as one using gear that restricts maneuverability, such as nets, lines, trawls, or trolling apparatus operated in that restrictive way - a boat trolling a couple of rods while remaining fully maneuverable does not meet that definition. B brings in an unrelated condition (anchored or not). C invents a size rule that doesn't exist. D is the exact overreading Rule 18's fishing-vessel definition is meant to prevent - gear that doesn't restrict maneuverability doesn't qualify, no matter how many lines are out.