Rules of the Road, Series IV – Rule 9 Explained

US Coast Guard District 13 LogoBy: Dan Shipman,
Recreational Boating Safety Specialist
13th Coast Guard District

Rule 9, Narrow Channels

NOTE: Hyperlinks are provided that will direct you to content that can better explain specific items or topics.

First, some definitions….


  1. The bed of a stream, river, or other waterway.
  2. A navigable route between two bodies of water.
  3. The deeper part of a waterway.
  4. A wide strait, as between a continent and an island.


The navigable portion of a river, harbor, or other partly enclosed bodies of water.

  1. The channel customarily navigated by vessels in such a body of water.

How and when Rule 9 is applied is the least understood among recreational boaters. Most people think that a narrow channel is something that by the visible lack of distance, from bank to bank, defines what is narrow. Although this can be true on some bodies of water what actually makes a channel narrow under this rule are the physical characteristics of the vessel involved, the confines of the safe navigational depth of water, and the density of vessel traffic.

Unlike a car, a vessel’s turning apparatus is at the back end (stern).  In order for it to complete a turn, the stern of the vessel has to be moved from one side to the other, from the center, pushing the bow in the desired direction. In a vehicle, the front tires turn to pull the front around. This this is why cars have a much sharper turning radius than a vessel.  What is common is that both a vessel and a car need forward momentum to turn, but when you replace tires on a roadway with a rudder or outdrive in the water, the physics are completely different.

Since a waterway is rarely a straight line for very long, you need to account for how a vessel moves through the water.  The larger the vessel, the less maneuverable it is and the more time and distance it needs to turn or stop -especially in shallower water.  “Head reach,” or the stopping distance and “advance and transfer”, the distance and radius it takes to turn, are present in all types of vessels to some extent. But as the available area to navigate decreases and vessel size increases, more maneuvering room is required. Smaller recreational vessels have an obligation to operate in a manner that does not impede the movement of these larger, less maneuverable vessels from safe passage.

As an example, you have a waterway that is a mile and a half across; the charted “navigable channel” is only 300 yards across and the depth is only 35 feet. You have a large 400-foot vessel that draws 30 feet of draft (the keel is 30 feet below the water line). That vessel can only safely navigate within the channel where there is enough water depth to prevent it from running aground (when keel meets bottom). On the surface, it may look like there’s plenty of water for it to maneuver but in reality, it’s trapped. Large deep draft vessels take a significant amount of area to turn and take up to, or over, a mile to come to a full stop. Take this same waterway and a 30-foot cabin cruiser that draws 3 feet.  This vessel can easily maneuver freely or stop, in any portion of the waterway to avoid a collision. Rule 9 does not apply to the cabin cruiser.  But take the same 30-foot cabin cruiser and add a large group of smaller vessels or paddle craft, the situation may change.

Traffic density can also apply to Rule 9 in this scenario (b) a vessel of less than 20 meters in length (65.6ft) or a sailing vessel shall not impede the passage of a vessel that can safely navigate only within a narrow channel or fairway. In application, this same theory applies as the vessel goes down in length.  Simply put, if the navigable channel width and depth only allow a vessel to safely navigate within its boundaries and/or the amount of vessel traffic impede other vessels from safely navigating in the narrow confines of a channel or fairway, Rule 9 applies.

Some basic uniform rules help tremendously in reducing user conflicts in these situations which, in turn, significantly reduces or prevents the risk of collision.  We know that if you are operating a vessel under 65 feet you can’t impede larger vessels. The best way to alleviate any risk of collision or conflict is when traveling in a channel or fairway; you should keep to the right side of the channel to allow other, larger or faster vessels, room to safely navigate.  If you intend to cross the channel, wait for larger traffic to pass and cross at an angle as close to 90 degrees from the prevailing direction of travel as safely as possible.  This should be the standard for all paddle craft operation.

 (a)(i) 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.

(d) A vessel must not cross a narrow channel or fairway if such crossing impedes the passage of a vessel which can safely navigate only within such channel or fairway. The latter vessel must use the signal prescribed in Rule 34(d) (§83.34(d)) if in doubt as to the intention of the crossing vessel.

So on a warm sunny weekend, different size and types of boats doing different activities may jockey for the same piece of water.  Looking at Rule 2 and Rule 9, what can we take away?  The first step is to be keenly aware of how you operate your own vessel and how your actions affect vessels you encounter that have limited maneuverability. Courtesy and patience go a long way in maintaining a safe boating environment. Stick to these basic rules and discipline yourself to follow them.

Finally, let’s talk about anchoring in the channel.

 (g) Any vessel shall, if the circumstances of the case admit, avoid anchoring in a narrow channel.

There seems to be a lot of individual interpretation with this part of Rule 9 that mostly centers on what exactly is meant by “the channel”. Having to anchor in the channel for an emergency is pretty much covered under the “circumstances of the case admits” clause. Any other time, anchoring in the channel is discouraged and in some cases, where state law is stricter than federal law, it can be prohibited. Taking into account what we previously discussed, anchoring in the channel would become problematic when other vessels are trying to safely navigate. This is especially the case when a vessel’s draft and maneuverability restrict it to specific limits within the channel.  There is no expectation that every recreational boater knows the design characteristics of each and every vessel because they’re all different. What they do need to know is that no vessel should anchor in a narrow channel unless it is an emergency.

Recreational boaters near the main navigation channel on the Columbia River.

In any situation where a vessel feels that a risk of collision exists and is in doubt that the necessary actions are being taken to avoid a collision, that vessel shall sound at least five short and rapid blast of the horn, Rule 34. (d) When vessels in sight of one another are approaching each other and, from any cause, either vessel fails to understand the intentions or actions of the other, or is in doubt whether sufficient action is being taken by the other to avoid collision, the vessel in doubt shall immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. Such signal may be supplemented by a light signal of at least five short and rapid flashes. Once five short blasts have been sounded, all vessels shall proceed as if the risk of collision exists and act in accordance with these rules. This is especially important if you are operating in a narrow channel or anchored in the channel.  You are at risk of collision because your action or inactions have left the other vessel in doubt as to your intentions and also as a warning that under the current situation you are at risk of collision. If you are anchored in the channel you need to move in ample time for the other vessel to safely pass.

Now, let’s talk about paddle craft.

An Oregon paddler…

Everyone has the right to enjoy the water and to be able to safely recreate. As Boaters, we also have the obligation to comply with these rules, and there’s a reason.  As I mentioned earlier, paddle craft or non-motorized vessels are not specifically mentioned. However they meet the definition of a vessel in Rule 3, so there are two schools of thought:  1) because they are not specifically mentioned, non-motorized vessels have no position of hierarchy in Rule 18, and therefore must stay clear of all other vessels; and, 2) if paddle craft or non-motorized vessels were mentioned in the rules, where would they fit in that hierarchy? Compared to other small vessels, paddle craft are relatively maneuverable -yet slow. They are low to the water and very hard to spot visibly at a distance. The Coast Guard’s position is that the second school thought is most applicable. The rules do apply to these users and therefore, we need to figure out how they exactly fit in.

As I look at the rules, Rule 9 fits best when it comes to the operation of non-motorized vessels.  Where most of the problems occur with user conflict between motorized and non- motorized vessels is in areas where there is restricted space and a heavy concentration of boaters. We know everyone has to comply with the ‘Big 4” rules; proper lookout (5) safe seed (6) risk of collision (7) and actions to avoid collision (8). So rule 9 is the most appropriate to apply:

 a)(i) 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. Avoid impeding other vessels by transiting on the right-hand side of the channel; this also meets the spirit of Rule 2, ordinary practice of good seamanship.

(b) A vessel of less than 20 meters in length (65.6 feet) or a sailing vessel shall not impede the passage of a vessel that can safely navigate only within a narrow channel or fairway. And,

(d) a vessel must not cross a narrow channel or fairway if such crossing impedes the passage of a vessel which can safely navigate only within such channel or fairway. The latter vessel must use the signal prescribed in Rule 34(d) (§83.34(d)) if in doubt as to the intention of the crossing vessel.

ACA’s Rules of the Road Graphic

These are basic rules to follow. Stay to the right of the channel. Cross the channel at right angles with due regard to the other traffic transiting the channel. If you are unsure of the other vessel’s intentions, sound five short blasts of a horn or whistle.  The only exceptions to these rule would be if the vessels were operating in a marine event permitted by the Coast Guard but, realize that even in that situation if a risk of collision exists, always revert to the rules.

If for any reason there is a need to impose a regulatory restriction on boat operations for navigation on a waterway, it is not accomplished under this rule.  Restrictions relating to safety and security, such as safety zones, and security zones can be placed on a waterway by the local Coast Guard Captain of the Port (COPT). For short-term issues such as marine events, the Coast Guard may issue a safety zone. In areas requiring security enforcement, a security zone can be put into place. For long-term restrictions to a waterway, a Regulated Navigation Area, (RNA) can be implemented.  When these types of restrictions or regulations are implemented, the public is notified by the Local Notice to Mariners (LNM) or annually re-occurring events listed in 33 Code of Federal Regulations (33 CFR). The LNM is published daily by the regional Coast Guard District. It contains any aids to navigation discrepancies, special notices on waterway issues, chart corrections, advanced notice of changes, bridge discrepancies, marine events, waterway closures, basically everything that is going on that affects navigation and commerce.

What this all comes down to is having an agreed upon, orderly set of rules that are simple to understand and follow. On a nice summer day, you want to go to the water and relax, just like everyone else. The last thing anyone needs is the stress, frustration, and aggravation that come with encountering others who operate their boats with reckless abandon or no regard for the rules and rights of others. Everyone has the right to recreate on our waterways, but with that right comes a responsibility to do so with civility and operate in an orderly manner with due regard to the rights of others. If everyone follows the rules, you can avoid those tense, frustrating and aggravating situations.  Bad days can be totally avoided. Safe boaters are happy boaters!



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