My boat goes thru a coast guard approved safety check - http://cgaux.org/vsc/ - prior to going in the water:
PDF's (coast guard approved and 1 throwable) , air horn, lights (nav & handheld), flares, fire extinguisher, small tools, documentation, anchor, extra rope
Then the carry-ons are sunscreen, fishing equip, water, an extra 5 gals of gas, hat and sunglasses.