Official rule text as published in the U.S. Coast Guard Navigation Rules
(a) A vessel proceeding along the course of a narrow channel or fairway shall keep as near to the outer limit of the channel or fairway which lies on her starboard side as is safe and practicable.
| Inland |
|---|
| (a)(ii) Notwithstanding Rule 9(a)(i) and Rule 14(a), a power-driven vessel operating in a narrow channel or fairway on the Great Lakes, Western Rivers, or waters specified by the Secretary, and proceeding downbound with the following current shall have the right-of-way over an upbound vessel, shall propose the manner and place of passage, and shall initiate the maneuvering signals prescribed by Rule 34(a)(i), as appropriate. The vessel proceeding upbound against the current shall hold as necessary to permit safe passing. |
(b) A vessel of less than 20 meters in length or a sailing vessel shall not impede the passage of a vessel [which] [that] can safely navigate only within a narrow channel or fairway.
(c) A vessel engaged in fishing shall not impede the passage of any other vessel navigating within a narrow channel or fairway.
(d) A vessel [shall] [must] not cross a narrow channel or fairway if such crossing impedes the passage of a vessel which can safely navigate only within that channel or fairway. The latter vessel [may] [must] use the signal prescribed in Rule 34(d) if in doubt as to the intention of the crossing vessel.
(e)(i) In a narrow channel or fairway when overtaking can take place only if the vessel to be overtaken has to take action to permit safe passing,, the power-driven vessel intending to overtake another power-driven vessel shall indicate her intention by sounding the appropriate signal prescribed in Rule 34(c)(i) and take steps to permit safe passing. The power-driven vessel to be overtaken shall,being overtaken, if in agreement, soundshall sound the appropriate signal prescribed in Rule 34(c)(ii)same signal and may, if specifically agreed to, take steps to permit safe passing. If in doubt she mayshall sound the signalssignal prescribed in Rule 34(d).
(e)(ii) This rule does not relieve the overtaking vessel of her obligation under Rule 13.
(f) A vessel nearing a bend or an area of a narrow channel or fairway where other vessels may be obscured by an intervening obstruction shall navigate with particular alertness and caution and shall sound the appropriate signal prescribed in Rule 34(e).
(g) Any vessel shall, if the circumstances of the case admit, avoid anchoring in a narrow channel.
Color note: black text applies generally; blue is International Waters; green is Inland Waters.
MyCOLREGS explanation
Summary
Rule 9(a) requires a vessel moving along a narrow channel or fairway to stay as near as is safe and practicable to the outer limit of the channel that lies on her starboard side. On the Great Lakes, Western Rivers, and certain other waters specified by the Secretary, Inland Rule 9(a)(ii) adds a further wrinkle: a power-driven vessel proceeding downbound with a following current gets priority over one heading upbound, and is the one that proposes how and where the two vessels will pass. Rule 9 also protects vessels that have no other option: a vessel under 20 meters, a sailing vessel, or a vessel engaged in fishing must not impede the passage of a vessel that can only safely navigate within the channel, and a vessel should not even cross the channel if doing so would impede that vessel - if there's doubt about a crossing vessel's intentions, the confined vessel can use the Rule 34(d) doubt signal.
Real World Example
Keeping to the starboard edge in a channel isn't just tidiness - it's what lets two vessels meeting head-on in a dredged cut pass port-to-port without radio contact or negotiation, purely because each one knows where the other is supposed to be. A large ship confined to a dredged channel isn't being stubborn when she holds her course - leaving the channel to dodge a small boat means running aground, so for her, giving way is often not physically possible no matter how badly her captain might want to.
Practice Questions
Q1. You are proceeding along a dredged harbor channel with room to spare. Under Rule 9(a), what should you generally do?
A. Keep as near to the outer limit of the channel that lies on your starboard side as is safe and practicable.
B. Favor the middle of the channel for the smoothest water, since Rule 9 is primarily concerned with avoiding shallow water near the banks.
C. Favor whichever side has less current, regardless of which side that is.
D. Keep to the port side of the channel, mirroring the starboard-side rule used for narrow channels in most other jurisdictions.
Q2. A 28-foot powerboat wants to cross a dredged ship channel where a deep-draft vessel can only safely navigate within the channel itself. What does Rule 9(b)/(d) require of the small boat?
A. Only sailing vessels are restricted under Rule 9(b); power-driven vessels under 20 meters may cross or navigate the channel freely since the rule was written to protect sailing traffic specifically, not motorized small craft.
B. The small boat may cross freely as long as it does so quickly, since Rule 9 only restricts vessels that linger in or travel along the channel, not ones making a brief crossing.
C. The small boat, being under 20 meters, must not impede the passage of the vessel that can only safely navigate within the channel, and under 9(d) should not even cross the channel if doing so would impede that vessel.
D. Nothing — vessels under 20 meters are exempt from Rule 9 entirely, since the rule's narrow-channel provisions were designed around larger commercial traffic that cannot leave the dredged channel at all.