The federal trigger is passenger-for-hire
The key phrase is not yacht, boat size, or whether the hull looks commercial. It is passenger for hire. 46 U.S.C. 2101 defines a passenger for hire as someone whose carriage depends on consideration flowing directly or indirectly to the owner, charterer, operator, agent, or another interested person.
That means a sunset cruise with friends for free is a very different federal credential question from a trip sold through a booking platform, a paid sightseeing run, a paid fishing charter, or a corporate outing where the vessel operator is compensated as part of the package. State boating education, insurance, marina, and local business rules can still apply, but those are separate from the federal OUPV/Master credential question.
Six or fewer paying passengers: OUPV territory
For a self-propelled uninspected passenger vessel under 100 GRT, 46 CFR 15.605 requires the vessel to be under the direction and control of a Coast Guard-credentialed OUPV or equivalent operator. The USCG National Maritime Center describes OUPV as the endorsement for uninspected passenger vessels that are limited by law to six or fewer passengers for hire.
This is why the credential is called the Six-Pack. It is not six guests plus unlimited paying riders; it is a federal passenger-for-hire ceiling for the uninspected-vessel lane. Typical examples are small charter fishing boats, private tour boats, dive boats, and whale-watching or sightseeing boats operating with six or fewer paying passengers.
More than six passengers: Master and inspection analysis
If the business model needs more than six passengers for hire, do not try to solve it with a Six-Pack credential. 46 CFR 15.805 requires an appropriately endorsed Master in command of inspected passenger vessels and inspected small passenger vessels. The vessel itself may need a Certificate of Inspection and Subchapter T/K compliance depending on tonnage, route, overnight carriage, and passenger count.
The practical rule: OUPV is the small uninspected path; Master plus inspected-vessel compliance is the larger passenger path. Before buying a boat for seven or more paying passengers, confirm the inspection route, stability, lifesaving equipment, manning, and allowed passenger count with the local USCG sector or a qualified maritime compliance professional.
Crewed charter and bareboat edge cases
A bareboat or demise charter can be different from a passenger-for-hire operation only when the charterer genuinely takes possession and control of the vessel, chooses the crew independently, and the owner does not provide or specify the crew. If the owner packages the boat with a captain, requires a specific captain list, or keeps operational control, the charter can look like carriage with crew provided and should be treated as a USCG credential/compliance issue before money changes hands.
This is the area where recreational-yacht owners get into trouble: calling the booking a bareboat charter does not override the actual control, crew, and compensation facts. If the owner or platform is selling a crewed experience, analyze it as commercial passenger service.
International trips and route limits
OUPV route authority matters. The NMC notes that OUPV Near Coastal endorsements may be limited to 100 miles offshore, Inland, or Great Lakes based on service, and that no OUPV endorsement is valid for international voyages. A yacht trip from Florida to the Bahamas with paying passengers is not just a longer Six-Pack trip.
For cross-border or offshore passenger service, verify the credential route, vessel documentation, customs/immigration rules, and passenger-vessel compliance before advertising the trip. The OUPV-vs-Master and Near-Coastal-vs-Inland guides are the next decision points once you know whether the voyage is private, for-hire, inland, near-coastal, or international.