D.C. Mun. Regs. tit. 19, r. 19-1038
No word, letters, or characters which advertise, in any manner, any activity, event, location, business, commodity, or product not existing, maintained, located, conducted, or sold on a vessel shall be placed on, attached to, or maintained on the exterior of that vessel, or any part or appurtenance of that vessel, without a permit issued by the Mayor.
No sign, banner, or flag advertising a business conducted on, or commodities or products sold on, any vessel of a size greater than ten square feet in area shall be painted on, printed on, placed on, attached to, or maintained on the exterior of the vessel.
No more than two (2) signs, ten square feet or less in area, may be used on any vessel. The signs shall be displayed with one (1) sign on the port side and one (1) sign on the starboard side of the vessel.
D.C. Mun. Regs. tit. 19, r. 19-1038