[I]t shall be lawful for all collectors, and the officers of the revenue cutters herein after mentioned, to go on board of ships or vessels in any part of the United States, or within four leagues [about 12 miles] of the coast thereof, if bound to the United States, whether in or out of their respective districts, for the purposes of demanding the manifests aforesaid, and of examining and searching the said ships or vessels; and the said officers respectively shall have free access to the cabin, and every other part of a ship or vessel
The Coast Guard may make inquiries, examinations, inspections, searches, seizures, and arrests upon the high seas and waters over which the United States has jurisdiction, for the prevention, detection, and suppression of violations of laws of the United States. For such purposes, commissioned, warrant, and petty officers may at any time go on board of any vessel subject to the jurisdiction, or to the operation of any law, of the United States, address inquiries to those on board, examine the ship’s documents and papers, and examine, inspect, and search the vessel and use all necessary force to compel compliance. When from such inquiries, examination, inspection, or search it appears that a breach of the laws of the United States rendering a person liable to arrest is being, or has been committed, by any person, such person shall be arrested or, if escaping to shore, shall be immediately pursued and arrested on shore, or other lawful and appropriate action shall be taken; or, if it shall appear that a breach of the laws of the United States has been committed so as to render such vessel, or the merchandise, or any part thereof, on board of, or brought into the United States by, such vessel, liable to forfeiture, or so as to render such vessel liable to a fine or penalty and if necessary to secure such fine or penalty, such vessel or such merchandise, or both, shall be seized.
A boarding usually sends two officers onto the other vessel. The rest of the crew remains on the response boat, which moves off to a safe distance. Once aboard, the boarding officers quickly assess the situation (number, size, and strength of people; weapons aboard), then proceed with the safety inspection while the other two officers aboard the Coast Guard vessel assure the overall security of the scene.
Boardings typically fall into one of three categories,” says [Petty Oficer 2nd Class David] Carrier. “A response to a marine incident, such as a tanker grounding or a boating accident. A boat operating in an unsafe fashion. And preventive, in which we check for safety equipment and compliance with U.S. Coast Guard rules and regulations.”… The boardings can be of any type of vessel, whether recreational, commercial (say, a passenger-carrying vessel or workboat), and yes, even dinghies and kayaks. The Coast Guard won’t hesitate to stop or board a sailboat that’s under full sail.