Bring bathing suits, a few shirts, and sunscreen. Bring a deck of cards (or CAH) in case you have a truly rainy day. Unless you're captaining the boat, anything more is unnecessary, IMO. My last trip I brought only a backpack, and half of it was full of sundries for the boat (e.g. clothespins, handheld s2s radio, fishing tackle, a length of cordage, and 12V LED Christmas lights).

If this is your first trip, you're going to pack too much - it's part of the game. But, make note of what you truly didn't need or use, and remember to leave it behind on your next trip... and there will be a next one! Enjoy <img src="http://www.traveltalkonline.com/forums/images/graemlins/Cheers.gif" alt="" />