If the price is the same, leave out of St. Thomas! That will save a ton of money in ferry costs for 15 people. Your cost for the boat should be free for organizing that many. As in, have them all pay slightly more to cover you! This year planning for six has been an absolute nightmare for me as far as collecting money. My other two couples still owe me for the provision order and we leave in 25 days. I told them the boat will not leave the dock with them on it until I have the money in hand. Don't get in a position of collecting during or after the trip! Last charter one couple waited until the last day of the trip to give me their share for the boat envelope which we use for moorings, fuel, water, ice and trash. I reminded, bugged them every day and just got "oh yeah, yeah, I'll get that to you". Only downside to leaving out of St. Thomas in your situation as I understand is you would be on the boat with the owner as captain? I don't think I'd like that. Not with a group that large. I'd rather have a captain supplied by the charter company. That way if you got someone you really didn't like for some reason you could swap out. Owners have more rules and could be particular about things since it's their boat!