1001.1 The owner of each vessel using District Waters, unless specifically exempted under §§ 1001.2 or 1001.5, shall register with the Harbor Master in the manner provided in § 1002.

1001.2 The following vessels shall be exempt from registration while they are temporarily using District waters, in accordance with §§ 1001.3 and 1001.4:

1. (a) Vessels that are covered by a Certificate of Number and Registration, in full force and effect, issued by the Coast Guard or by a state or United States territory with a federally approved numbering system;
2. (b) Vessels that are from a country other than the United States; and
3. (c) Vessels documented by the Coast Guard.

1001.3 Use of a vessel listed in § 1001.2 in District Waters for a period in excess of fifty (50) consecutive days shall create a rebuttable presumption that the use is no longer temporary, and that the vessel should be registered in the District.

1001.4 Use of a vessel listed in §1001.2 in District waters for a period of one hundred and eighty-three (183) days or more during any calendar year shall be prima facie evidence that the use is no longer temporary and that the vessel should be registered in the District of Columbia.

1001.5 The following vessels shall be exempt from registration:

1. (a) A military or public vessel of the U.S. government, other than a recreational type public vessel;
2. (b) A vessel owned by a state, or any subdivision of a state, which is used principally for governmental purposes, and which is clearly identifiable as such;
3. (c) A vessel's lifeboat, if the lifeboat is used solely for lifesaving purposes;
4. (d) A vessel used exclusively for racing; and
5. (e) A vessel operating during the period, not to exceed thirty (30) days, following the filing of an application for a Certificate of Number; provided, that visible evidence of the application shall be present on the vessel.

SOURCE: Article 29 § 4(a)(1)-4(a)(2) of the Police Regulations of the District of Columbia (January 1983).