Groups up to 18 Passengers YES! Plan Sea is a U.S. Coast Guard-inspected commercial passenger vessel and is permitted to carry up to 22 passengers and two crew. There are hundreds of charter boats that allow up to six passengers and only a handful of boats that allow 6 to 18 passengers. For most cruises, we have limited the number of passengers to 18 or fewer so that our guests are more comfortable and less crowded. We think that 12 adults is the ideal group size.