Rules of the Road: COLREGS and Inland Differences
Two rule sets, one exam
The questions come from the International Regulations (72 COLREGS) and the Inland Navigation Rules. If a stem does not specify, assume U.S. inland waters. Most rules are identical, so spend study time on the differences: Inland narrow-channel guidance, bridge-to-bridge radiotelephone, and maneuvering signals.
Concepts you must know
Rule 5 lookout, Rule 6 safe speed, Rule 7 risk of collision (bearing drift), Rule 8 action to avoid collision, Rule 13 overtaking, Rule 14 head-on, Rule 15 crossing, Rules 16-17 give-way/stand-on, Rule 18 responsibilities between vessel types, Rule 19 restricted visibility, Rule 34 maneuvering signals, Rule 35 fog signals, and the lights, shapes, and sound signals in Parts C and D. Know the hierarchy: power-driven, sailing, fishing, not under command, restricted in ability to maneuver.
Traps
Inland Rule 34 signals are intent-based: one short blast means "I intend to leave you on my port side"; two short means "I intend to leave you on my starboard side"; three short means "I am operating astern propulsion." International signals are action-based: one short = altering to starboard; two = to port; three = astern. Inland narrow channels: keep as near the starboard edge as safe; International: keep near the outer limit of the channel on your starboard side. An overtaking vessel is always the give-way vessel, regardless of type. The stand-on vessel holds course and speed but may act when risk of collision is imminent.
Rule of thumb
For crossing power-driven vessels: if you see a red sidelight on your starboard bow, you are the give-way vessel and must not cross ahead; if you see green there, you are stand-on. When in doubt, take early, substantial action and never assume the other vessel will give way.