33 CFR 81.1: Definitions for COLREGS compliance exceptions
Last reviewed: October 14, 2026
This section defines three terms used in this part. They are 72 COLREGS, a vessel of special construction or purpose, and interference with the special function of the vessel. It sets no other requirements.
Applies toThe definitions apply as used in this part.
What it says
72 COLREGS means the International Regulations for Preventing Collisions at Sea, 1972, done at London, October 20, 1972, as rectified by the Proces-Verbal of December 1, 1973, as amended.
“72 COLREGS refers to the International Regulations for Preventing Collisions at Sea, 1972, done at London, October 20, 1972, as rectified by the Proces-Verbal of December 1, 1973, as amended.”
A vessel of special construction or purpose is a vessel designed or modified to perform a special function, whose arrangement is thereby made relatively inflexible.
“A vessel of special construction or purpose means a vessel designed or modified to perform a special function and whose arrangement is thereby made relatively inflexible.”
Interference with the special function of the vessel occurs when installing or using lights, shapes, or sound-signaling appliances under 72 COLREGS prevents or significantly hinders the operation in which the vessel is usually engaged.
“Interference with the special function of the vessel occurs when installation or use of lights, shapes, or sound-signaling appliances under 72 COLREGS prevents or significantly hinders the operation in which the vessel is usually engaged.”
Common questions
What does 72 COLREGS mean in 33 CFR 81.1?
It refers to the International Regulations for Preventing Collisions at Sea, 1972, done at London, October 20, 1972, as rectified by the Proces-Verbal of December 1, 1973, as amended.
“72 COLREGS refers to the International Regulations for Preventing Collisions at Sea, 1972, done at London, October 20, 1972, as rectified by the Proces-Verbal of December 1, 1973, as amended.”
What is a vessel of special construction or purpose?
It is a vessel designed or modified to perform a special function. Its arrangement is thereby made relatively inflexible.
“A vessel of special construction or purpose means a vessel designed or modified to perform a special function and whose arrangement is thereby made relatively inflexible.”
What counts as interference with the special function of a vessel?
Interference occurs when installing or using lights, shapes, or sound-signaling appliances under 72 COLREGS prevents or significantly hinders the operation in which the vessel is usually engaged.
“prevents or significantly hinders the operation in which the vessel is usually engaged.”
The text of 33 CFR 81.1
Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR
Definitions
As used in this part:
72 COLREGS refers to the International Regulations for Preventing Collisions at Sea, 1972, done at London, October 20, 1972, as rectified by the Proces-Verbal of December 1, 1973, as amended.
A vessel of special construction or purpose means a vessel designed or modified to perform a special function and whose arrangement is thereby made relatively inflexible.
Interference with the special function of the vessel occurs when installation or use of lights, shapes, or sound-signaling appliances under 72 COLREGS prevents or significantly hinders the operation in which the vessel is usually engaged.
The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.