In pockets:
*Flashlight - Keychain or pen size, waterproof, battery life >12 hours.
*Whistle - Flat "marine" whistle or any multi-chamber plastic whistle.
*Hand sanitizer - Ship wide sickness is more common then sinkings.

On body:
* Boat shoes - Not the slip on mocs, but the Vans or sneaker style laceups with flat outsoles and a thick rubber rand around the outside. I've used them for small boat sailing, and they will stick to any surface regardless of how wet or slick it is.
* Sunhat

In cabin:
*Passport, tickets, contacts, cash, compass, and how to ask "where is the American Embassy" in 149 different languages in a waterproof floating bag. On the cheap you can toss an empty (2.2 lbs/L bouyency) water bottle and a ziplock into a gym bag for waterproof and floating.
*water purification tablet
*Warm, windproof, jacket.