"WASHINGTON - The U.S. Coast Guard in a decisional memo dated Oct.3, classified paddleboards as vessels in accordance with Title 1 United States Code, Section 3.
This classification means that when used beyond the narrow limits of a swimming, surfing, or bathing area, no person may use a paddleboard unless in compliance with the Navigation Rules, and applicable carriage requirements for this type of vessel.
This may include a Coast Guard approved life jacket for each person on board, a sound producing device, visual distress signals, and proper navigation lights. A police-type whistle and a flashlight comply with these requirements.
The Coast Guard has also exempted the hull identification number requirement from the manufacturing standards.......
It is important to note that paddleboards in the surf-zone will not be affected by the decision and that the Coast Guard does not define the limits of surf zones....."
http://www.ratlines.com/SUBSpaddleboards.htm