US Inland Navigation Rules

Prerequisites

• The basic rules of the road from the shared lessons: stand-on and give-way vessels, crossing, head-on and overtaking situations.
• Knowing the difference between a short blast (about one second) and a prolonged blast (four to six seconds).

Learning Objectives

This lesson covers the navigation rules section of the ASA 101 and ASA 103 standards as they apply in US waters. By the end of it you will be able to:

• Explain the difference between the Inland Navigation Rules and the International Regulations (COLREGS), and say where each applies.
• Find the COLREGS demarcation lines and know that the rules can change in the middle of a trip.
• Use and answer the Inland maneuvering signals, and explain why an Inland signal is a proposal that needs agreement.
• Apply the crossing rule between power-driven vessels.
• Explain when a radio agreement replaces whistle signals.
• Know which boats must carry a copy of the Navigation Rules.

Two Sets of Rules

Most of the world uses one set of collision regulations: the International Regulations for Preventing Collisions at Sea, 1972 (COLREGS). The United States uses the COLREGS at sea, but has its own Inland Navigation Rules for harbors, bays, rivers and lakes.

The two sets are deliberately very close. They use the same rule numbers (Rules 1–38), the same stand-on and give-way logic, and almost the same lights. The differences are mostly in sound signals, a few lighting details, and special provisions for the Great Lakes and Western Rivers.

Where the Inland Rules live:

• 33 CFR Part 83 holds Rules 1–38.
• Parts 84–88 hold the Annexes (technical details of lights and shapes, sound equipment and so on).
• Part 89 holds implementing rules, including the waters where certain special Inland Rules apply.

Until 2010 the Inland Rules were written into the US Code. The Coast Guard then moved them into the Code of Federal Regulations, and a 2014 final rule (effective August 1, 2014) updated them to match recent COLREGS amendments. Older books may quote the 1980 statutory numbering. The rule numbers in 33 CFR 83 are the current ones.

Where the Line Is: COLREGS Demarcation Lines

The boundary between the two sets of rules is defined in 33 CFR Part 80, "COLREGS Demarcation Lines." It is organized by Coast Guard district and coastline, and typically runs across harbor entrances, from breakwater to breakwater or headland to headland.

• Landward of the line: Inland Rules.
• Seaward of the line: COLREGS.

On NOAA charts the demarcation line is printed as a dashed magenta line with the label "COLREGS Demarcation Line". A boat leaving harbor for a day sail along the coast crosses from one set of rules to the other and back again. You need to know which side you are on, mainly so you use and understand the correct sound signals.

The Inland Rules also apply to US boats on the Canadian waters of the Great Lakes, as far as they do not conflict with Canadian law.

Inland Maneuvering Signals

The biggest practical difference for a sailor is what the whistle means. Under Inland Rule 34, power-driven vessels in sight of one another, meeting or crossing within half a mile, use these signals:

The key word is intend. An Inland one- or two-blast signal is a proposal. The other vessel answers:

• Agree: sound the same signal back, and both vessels act on it.
• Disagree or unsure: sound the danger signal (at least five short, rapid blasts). Both vessels then slow down and sort it out, usually by radio.

Under the COLREGS, by contrast, one short blast means "I am altering my course to starboard". It describes an action already taking place, and no reply is expected. That is why the same blast can mean something different on either side of the demarcation line.

Overtaking signals (Inland)

• 1 short blast: "I intend to overtake you on your starboard side."
• 2 short blasts: "I intend to overtake you on your port side."
• The vessel being overtaken answers with the same signal if it agrees, or the danger signal if it does not.

Other signals you will hear

• One prolonged blast when approaching a bend or a place where other vessels may be hidden. Any vessel around the bend answers with a prolonged blast.
• One prolonged blast when a vessel leaves a dock or berth.
• Light signals may back up the whistle: one, two or three white or yellow flashes, each about one second long, with the same meanings.

Radio instead of whistle

Large vessels talk to each other on VHF under the Vessel Bridge-to-Bridge Radiotelephone Act. Under Inland Rule 34(h), if two vessels reach agreement by radio, they do not have to sound the whistle signals, although they may. If they cannot agree by radio, they must exchange whistle signals in good time, and the whistle signals prevail.

In practice, a towboat captain on a river is far more likely to call you on channel 13 or 16 and say "I'll see you on the one" (a port-to-port passing) than to blow the whistle. Answer clearly, then do what you agreed.

Sailboats and the Signals

Rule 34 maneuvering signals are for power-driven vessels. A sailboat under sail does not use them. But:

• Under engine, you are a power-driven vessel, even with the sails up. The power-driven rules and signals then apply to you.
• You must still understand the signals, because a ship or tug signalling you is telling you what it plans to do.
• Anyone, sail or power, should sound the danger signal if they do not understand another vessel's intentions or think it is not taking enough action to avoid a collision.

Small boats are required to carry some means of making an efficient sound signal. A horn is the usual choice. See the USCG safety equipment lesson.

Crossing Between Power-Driven Vessels

The crossing rule is the same in both sets: when two power-driven vessels are crossing with risk of collision, the vessel that has the other on her starboard side keeps out of the way, and avoids crossing ahead if she can.

• The vessel with the other on its starboard side is the give-way vessel. It acts early and obviously, usually by turning to starboard and passing astern.
• The other vessel is the stand-on vessel. It holds course and speed, but must still act to avoid a collision if the give-way vessel does not.

A handy reminder: at night the give-way vessel sees the other boat's red sidelight, which means stop. The stand-on vessel sees green, which means go (carefully).

Lights: Mostly the Same

A power-driven vessel underway shows a masthead light, sidelights and a sternlight in both sets of rules. A vessel 50 m or longer also shows a second masthead light, aft and higher. Under Inland Rule 23, a power-driven vessel under 12 m may combine the masthead and stern lights into a single all-round white light with sidelights. You will see this on most small motorboats.

The 2014 update also allowed some small sailing vessels and vessels under oars an optional all-round white light. Check the lights lesson for the full sets.

Great Lakes and Western Rivers

The Inland Rules contain special provisions for the Great Lakes and for the Western Rivers (the Mississippi river system is the well-known example). On those waters there are extra rules for towboats pushing barges, for vessels proceeding downstream (which often have the right of way in narrow channels) and for some light signals.

If you plan to sail on the Great Lakes or a Western River, read Part 83 and the waters listed in 33 CFR Part 89 for that area before you go. For most ASA coastal courses, these provisions are background knowledge only.

Carrying the Rules

The Coast Guard publishes the Navigation Rules and Regulations Handbook, which contains both the International and the Inland Rules side by side.

• Self-propelled vessels 12 meters (39.4 ft) or longer must carry a copy on board, as must commercial vessels. An electronic copy is acceptable if it can be shown when asked.
• Smaller boats are not required to carry one, but the Coast Guard and BoatUS recommend it. It is the best way to settle an argument in the cockpit.

Worked Example: Leaving Harbor

You motor out of a busy harbor in a 34 ft sailboat. You are inside the demarcation line, so the Inland Rules apply.

1. As you back out of the slip, you sound one prolonged blast to warn anyone coming down the fairway.
2. In the channel, a ferry is approaching head-on and sounds one short blast. Under the Inland Rules that is a proposal: "I intend to leave you on my port side." You agree, sound one short blast back, and keep to the starboard side of the channel. You pass port to port.
3. A tug calls on channel 13: "Sailboat outbound at the green can, this is the tug astern of you. I'll overtake you on the two." You reply that you agree to a port-side overtake and hold your course. No whistle is needed, because you agreed by radio.
4. Past the breakwater you cross the magenta demarcation line. You are now under the COLREGS. When a fishing boat sounds one short blast here, it means "I am altering course to starboard", and you do not need to reply.

Common Mistakes

• Using the COLREGS meaning in inland waters, or the other way round. Know which side of the demarcation line you are on.
• Not answering an Inland signal. Silence is not agreement. Answer with the same signal or with the danger signal.
• Forgetting that a sailboat under engine is a power-driven vessel. With the engine in gear, you give way like any motorboat.
• Assuming the sailboat always has right of way. Large ships restricted to a channel and commercial traffic may not be able to keep clear. A small boat must not impede them in a narrow channel.
• Not having a sound signal at all. Without a horn you cannot sound the danger signal.

Summary

• The US uses the COLREGS at sea and the Inland Navigation Rules (33 CFR Part 83) landward of the COLREGS Demarcation Lines (33 CFR Part 80).
• The rules are nearly identical. The main difference is sound signals.
• Inland one- and two-blast signals are proposals ("I intend to…"). Answer with the same signal to agree, or five or more short blasts if you disagree or are unsure.
• An agreement by VHF radio can replace whistle signals under Inland Rule 34(h).
• In a crossing, the power-driven vessel with the other on its starboard side gives way.
• Self-propelled vessels 12 m or longer must carry the Navigation Rules.

Check Your Understanding

1. Where do you find the boundary between Inland Rules and COLREGS waters? In 33 CFR Part 80, the COLREGS Demarcation Lines, also shown as a dashed magenta line on NOAA charts.
2. In inland waters, a power-driven vessel ahead sounds two short blasts. What does it mean, and how do you agree? "I intend to leave you on my starboard side." You agree by sounding two short blasts back.
3. What do you sound if you do not understand another vessel's intentions? At least five short, rapid blasts: the danger or doubt signal.
4. Two vessels agree a passing by VHF in inland waters. Must they also sound whistle signals? No. Under Inland Rule 34(h) they may, but they do not have to.
5. Which boats must carry a copy of the Navigation Rules? Self-propelled vessels 12 meters (39.4 ft) or longer, and commercial vessels.

Sources

• https://www.law.cornell.edu/cfr/text/33/part-80
• https://www.law.cornell.edu/cfr/text/33/83.01
• https://www.law.cornell.edu/cfr/text/33/83.15
• https://www.law.cornell.edu/cfr/text/33/83.23
• https://www.law.cornell.edu/cfr/text/33/83.34
• https://www.law.cornell.edu/cfr/text/33/part-84
• https://www.law.cornell.edu/cfr/text/33/part-89
• https://www.govinfo.gov/content/pkg/FR-2014-07-02/html/2014-14413.htm
• https://www.boatus.org/navigation-rules