One questioned to consider. Are you contracting for a captained boat to drive you from beach bar to beach bar? Or a crewed trip where your meals, drinks, and cleaning are done 24/7 for you? If you are one a boat where cleaning and hospitality is part of the offer you should get on the boat with a minimum of 20 percent of the total cost in cash. Depending on the level and quality of the service a minimum of 10 percent in cash is handed to the captain with your thanks on the last morning. If you and your group are delighted with the effort put forward that number should reach 20 percent of the total bottom line number of the cost paid for the boat and crew. You tip in cash, always to the captain, always on the last day and the minimum number is 10 percent.