Official rule text as published in the U.S. Coast Guard Navigation Rules
(d) The term "vessel engaged in fishing" means any vessel fishing with nets, lines, trawls, or other fishing apparatus which restrict maneuverability, but does not include a vessel fishing with trolling lines or other fishing apparatus which do not restrict maneuverability.
(e) The term "seaplane" includes any aircraft designed to maneuver on the water.
MyCOLREGS explanation
Summary
Rule 3(d) defines "vessel engaged in fishing" narrowly: fishing with nets, lines, trawls, or other gear that restricts maneuverability - not any boat with a line in the water. A boat trolling with rods that leave her free to turn or stop at will doesn't get that status, even though she's technically fishing. Rule 3(e) adds a much simpler definition: a seaplane is any aircraft designed to maneuver on the water, which is why Rule 3(a)'s broad "vessel" definition specifically calls out seaplanes as included.
Real World Example
The distinction shows up the moment two boats meet: 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 - maneuverability, not the presence of gear, is what the definition actually tracks.
Practice Questions
Q1. A floatplane is taxiing on the water surface near a marina entrance. Under Rule 3(e), is she a "vessel" subject to the Navigation Rules?
A. No - aircraft are never vessels under these Rules, regardless of whether they are on the water or in flight.
B. Yes - Rule 3(e) specifically includes seaplanes within the "vessel" definition when they are on the water.
C. Only if her engines are off, since a seaplane under power is treated the same as an aircraft in flight.
D. Only in restricted visibility, when Rule 3(e) treats a taxiing seaplane the same as any other vessel for safety purposes.
Q2. What test does Rule 3(d) use to decide whether a boat is "engaged in fishing" under the Rules?
A. Whether any fish have actually been caught.
B. Whether the vessel's registration lists "fishing" as its use.
C. Whether the gear in use restricts the vessel's ability to maneuver.
D. Whether the vessel exceeds 20 meters in length.
Practice Question Answers
Q1.
B. Yes - Rule 3(e) specifically includes seaplanes within the "vessel" definition when they are on the water. Rule 3(e) defines "seaplane" as any aircraft designed to maneuver on the water, and Rule 3(a)'s broad vessel definition explicitly lists seaplanes among the craft it covers. A denies seaplanes any status the Rules specifically grant them. C and D each invent a condition - engine state, visibility - that Rule 3(e)'s definition doesn't depend on.
Q2.
C. Whether the gear in use restricts the vessel's ability to maneuver. Rule 3(d) turns on maneuverability, not catch or paperwork: nets, trawls, and lines that restrict maneuvering qualify, while trolling lines that don't restrict it specifically do not. A and B each substitute an unrelated fact - actual catch, registration - for the rule's real test. D invents a size threshold Rule 3(d) doesn't contain.