Aside from the obvious, food , water, Galaga game a few odder things that I always have
Walmart plastic bags - the perfect size everything bag for a small boat
A coupel of of LED puck lights -in a pinch can be mast light, cabin light, running lights
100 feet of Walmart parachute cord. Cheap, don't mind cutting it
Toolbox, electrical tape, duct tape, sparkplugs, stiff wire,
Chinese lanterns -solar. Run up the topping lift mark, your boat in a crowded mooring
Dinghy anchor - beats using your battery and having it submerged where the beach used to be
ginger root capsules-3 bucks of seasick prevention Myth Busters endorsed