6 Pack to 100T Master's 10-day Class. Licenses are required in order to legally carry passengers for f=hire. this includes charters for fishing, sightseeing, diving, transportation, teaching, or any use which is considered a "passenger for hire," situation. Many companies require them for boat deliveries.
A Master License is required if you operate "inspected" vessels. Inspected vessels are allowed to carry more than 6-passengers. To become inspected, the vessel must be built in accordance with rigid USCG Commercial Vessel Inspection Standards.