There are companies that make dry bags that are day packs.Used by canoe and kayak fans for day trips.I can tell you for sure that if you have to life boats the crew will not let you bring luggage or bags of any kind.It has to be in your pockets or worn on the body if you want it with you.Life rafts only have room for people.Extra layer of clothes and fill your pockets would be my plan.Disembarking in a port grab the day pack and AM/Ex card........


BOATMAN
John