Paid charters may only carry 6 or 12 passengers at a time, unless it is a US Coast Guard Inspected Vessel. There are many factors to determine whether a boat may carry 6 or 12 in one trip. Primarily, vessels that weigh less than 100 GRT (gross tons) can carry up to 6 passengers; vessels greater than 100 GRT can carry up to 12 passengers. A boat can only carry more than 12 passengers if it is classified as a Recreational Vessel - manufactured and operated primarily for pleasure.
To find a boat with the correct capacity for your group use the filter “Guests” on Sailo’s search page and enter your expected number of guests.