D.C. Mun. Regs. tit. 19, r. 19-1004
Vessels, other than documented vessels, required to be registered pursuant to § 1001, shall be numbered in accordance with this section.
No person shall operate or give permission for the operation of any vessel on District waters, unless the vessel is numbered in accordance with this section, a numbering system administered by the Coast Guard, or a federally approved numbering system of a state or a U.S. territory.
The Certificate of Number issued to the owner of a vessel shall be available at all times for inspection on the vessel for which it is issued whenever the vessel is in use.
The Certificate of Number for a readily identifiable livery boat of less than twenty-six feet (26 ft.) in length which is leased, rented, or chartered to another person for that person's noncommercial use for less than seven (7) days may be retained on shore by the vessel owner or the owner's representative at the place from which the vessel departs or returns to the possession of the owner or the owner's representative.
A copy of the lease or rental agreement for a vessel that is leased, rented, or chartered under § 1004.4, that has been signed by the owner or the owner's representative and the person renting, leasing, or chartering the vessel must be in the possession of the operator on board the vessel.
The copy of the lease or rental agreement for a vessel that is leased, rented, or chartered under § 1004.4 shall contain at least the identification number and the period of time for which the vessel is rented, leased, or chartered.
The identification number contained in the Certificate of Number shall be displayed on each side of the forward half of the vessel in a position where the number is distinctly visible and legible.
The identification numbers displayed on a vessel shall read from left to right, and shall be in block characters of good proportion not less than three inches (3") in height.
The identification number shall have spaces or hyphens that are equal to the width of a letter other than "i" or the number "1" between the letter and number grouping (For example: DC 5678 EF or DC-5678-EF).
The identification number shall be of a color that will contrast with the color of the background, and shall be maintained to be clearly visible and legible.
When a vessel is used by a manufacturer or dealer for testing or demonstration, the identification number may be painted on or attached to removable plates that are temporarily but firmly attached to each side of the forward half of the vessel.
On vessels configured so that a number on the hull or superstructure would not be easily visible, the number must be painted on or attached to a backing plate attached to the forward half of the vessel so that the number is visible from each side of the vessel.
Except on documented vessels, no number other than the current identification number validly assigned to the vessel shall be painted, attached, or otherwise displayed on each side of the forward half of the vessel.
The annual validation sticker issued by the Harbor Master for an undocumented vessel shall be displayed on the vessel within six inches (6") of the vessel identification number.
The annual validation sticker issued by the Harbor Master for a documented vessel shall be conspicuously displayed on the forward half of the vessel.
Nothing in this section prohibits the registration of any vessel under this chapter upon the request of the owner, even though that vessel is exempt from registration under § 1001.2 or 1001.5 of this chapter.
The Harbor Master is authorized to issue hull identification numbers in accordance with 33 CFR § 181.
If a department or agency of the U.S. government has in force an overall system of numbering identification for vessels within the United States, the numbering system administered by the Harbor Master pursuant to this section shall conform to that federal numbering system.
D.C. Mun. Regs. tit. 19, r. 19-1004