COLREGs · Rule 1 · 33 CFR §83.01

Application

Defines the geographic scope of the rules: COLREGs applies on the high seas and connected waters; the Inland Rules apply inside the demarcation lines on US inland waters.

What does Rule 1 actually say?#

Source

Verbatim 33 CFR §83.01, public domain. The international COLREGs text is published by the IMO and cannot be reproduced here; this U.S. wording tracks it closely.

These Rules apply to all vessels upon the inland waters of the United States, and to vessels of the United States on the Canadian waters of the Great Lakes to the extent that there is no conflict with Canadian law. (b)(i) These Rules constitute special rules made by an appropriate authority within the meaning of Rule 1(b) of the International Regulations for Preventing Collisions at Sea, 1972, including annexes currently in force for the United States (“International Regulations”).

All vessels complying with the construction and equipment requirements of the International Regulations are considered to be in compliance with these Rules.

Nothing in these Rules shall interfere with the operation of any special rules made by the Secretary of the Navy with respect to additional station or signal lights and shapes or whistle signals for ships of war and vessels proceeding under convoy, or by the Secretary with respect to additional station or signal lights and shapes for fishing vessels engaged in fishing as a fleet. These additional station or signal lights and shapes or whistle signals shall, so far as possible, be such that they cannot be mistaken for any light, shape, or signal authorized elsewhere under these Rules. Notice of such special rules shall be published in the Federal Register and, after the effective date specified in such notice, they shall have effect as if they were a part of these Rules.

Traffic separation schemes may be established for the purpose of these Rules. Vessel traffic service regulations may be in effect in certain areas.

Whenever the Secretary determines that a vessel or class of vessels of special construction or purpose cannot comply fully with the provisions of any of these Rules with respect to the number, position, range, or arc of visibility of lights or shapes, as well as to the disposition and characteristics of sound-signaling appliances, the vessel shall comply with such other provisions in regard to the number, position, range, or arc of visibility of lights or shapes, as well as to the disposition and characteristics of sound-signaling appliances, as the Secretary shall have determined to be the closest possible compliance with these Rules. The Secretary may issue a certificate of alternative compliance for a vessel or class of vessels specifying the closest possible compliance with these Rules. The Secretary of the Navy shall make these determinations and issue certificates of alternative compliance for vessels of the Navy.

The Secretary may accept a certificate of alternative compliance issued by a contracting party to the International Regulations if it determines that the alternative compliance standards of the contracting party are substantially the same as those of the United States.

The operator of each self-propelled vessel 12 meters or more in length shall carry, on board and maintain for ready reference, a copy of these Rules. [USCG-2012-0102, 79 FR 37912, July 2, 2014, as amended by USCG-2022-0071, 87 FR 54390, Sept. 6, 2022]

Practice this rule#

One real exam question on this rule, cited to source. No sign-up.

Rule 18 — Responsibilities Between Vessels

Rules 11 through 18 of the Inland Navigation Rules apply only when which condition is met?

How does Inland Rule 1 differ from COLREGs?#

Inland Rule 1 references the demarcation lines published in 33 CFR Part 80.

21 of 38 rules differ somewhere; the five the exam leans on are Rule 9, Rule 10, Rule 24, Rule 28 and Rule 34, side by side on Inland vs International Rules.

Why it shows up on the exam#

Demarcation-line questions (which set of rules applies where) come up most often on Near-Coastal exams.

What does the exam actually test here?#

Where they apply
Inland waters of the U.S.
The Inland Rules govern shoreward of the COLREGs demarcation lines, plus U.S. vessels on the Canadian waters of the Great Lakes where there is no conflict with Canadian law. Seaward of the demarcation line, the International Rules apply.
Carriage requirement
12 metres or more
The operator of every self-propelled vessel 12 metres or more in length must carry a copy of the Inland Rules on board and maintain it for ready reference. This is a favourite exam detail because the threshold is easy to confuse with the 20-metre thresholds elsewhere in the Rules.
Alternative compliance
Certificate, not an excuse
A vessel that physically cannot meet the light, shape, or sound-appliance requirements complies with what the Secretary determines to be the closest possible compliance, evidenced by a certificate of alternative compliance. Nothing in Rule 1 lets a vessel simply ignore a requirement.

Rule 1 — common exam questions#

What waters do the Inland Navigation Rules apply to?

They apply to all vessels upon the inland waters of the United States, and to U.S. vessels on the Canadian waters of the Great Lakes to the extent there is no conflict with Canadian law (33 CFR §83.01(a)).

Do I have to carry a copy of the Rules on board?

Yes if your vessel is self-propelled and 12 metres or more in length. Rule 1(g) requires the operator to carry a copy on board and maintain it for ready reference (33 CFR §83.01(g)).

What is a certificate of alternative compliance?

Where a vessel of special construction or purpose cannot fully comply with the requirements for number, position, range, or arc of visibility of lights or shapes, or for sound-signalling appliances, the Secretary determines the closest possible compliance and may issue a certificate saying so (33 CFR §83.01(e)). The Secretary of the Navy does this for Navy vessels.

Which rule set applies where the two meet?

The dividing line is the navigational demarcation line separating the high seas from harbors, rivers, and other inland waters, defined at 33 CFR §83.03(q). Inside it you are on the Inland Rules; outside it, the International Rules.

Authoritative source#

33 CFR §83.01 — this section with its neighbours. 33 CFR Part 83 is public domain; checked 2026-05-16.
COLREGs Rule 1 is published by the IMO and is authoritative internationally.

Practise this rule against the real exam.

Real exam questions. No signup, no card.

See if you'd pass today How it works

Was this page helpful?