The International Rules were formalized in the Convention on the International Regulations for Preventing Collisions at Sea, 1972, and became effective on July 15, 1977. The Rules (commonly called 72 COLREGS) are part of the Convention, and vessels flying the flags of states ratifying the treaty are bound to the rules. The United States has ratified this treaty and all United States flag vessels must adhere to these Rules where applicable. President Gerald R. Ford proclaimed 72 COLREGS and the Congress adopted them as the International Navigation Rules Act of 1977.
The 72 COLREGS were developed by the Inter-Governmental Maritime Consultative Organization (IMCO) which in May 1982 was renamed the International Maritime Organization (IMO). In November 1981, IMO's Assembly adopted 55 amendments to the 72 COLREGS which became effective on June 1, 1983. The IMO also adopted 9 more amendments which became effective on November 19, 1989. The International Rules in the Navigation Rules book published by the Coast Guard and the rules listed here contain these amendments.
These Rules are applicable on waters outside of established navigational lines of demarcation. The lines are called COLREGS Demarcation Lines and delineate those waters upon which mariners shall comply with the Inland and International Rules. COLREGS Demarcation lines are contained in Title 33 of the Code of Federal Regulations, part 80 (33 CFR 80), the Navigation Rules manual, or here.
The International and Inland Navigation Rules have been combined in the Online NavRules pages. If you want a copy of just the International Rules, you can download it in various formats.
The Inland Rules replace the old Inland Rules, Western Rivers Rules, Great Lakes Rules, and their respective pilot rules and interpretive rules, and parts of the Motorboat Act of 1940. Many of the old navigation rules were originally enacted in the 1800s. Occasionally, provisions were added to cope with the increasing complexities of water transportation. Eventually, the navigation rules for United States inland waterways became such a confusing patchwork of requirements that in the 1960's several attempts were made to revise and simplify them. These attempts were not successful.
Following the signing of the Convention on the International Regulations for Preventing Collisions at Sea, 1972, a new effort was made to unify and update the various inland navigation rules. This effort culminated in the enactment of the Inland Navigation Rules Act of 1980. This legislation sets out Rules 1 through 38 - the main body of the Rules. The five Annexes were published as regulations. It is important to note that with the exception of Annex V to the Inland Rules, the International and Inland Rules and Annexes are very similar in both content and format.
The effective date for the Inland Navigation rules was December 24, 1981, except for the Great Lakes where the effective date was March 1, 1983.
The International and Inland Navigation Rules have been combined in the Online NavRules pages. If you want a copy of just the Inland Rules, you can download it in various formats.