His Lifeboat
His lifeboat was about 6 feet in diameter, and he was able to bring eight pints of water, 3 pounds of food, a makeshift spear, and a solar still, amongst a few other things. It was pretty much all he would have to try and survive in the open ocean. He was literally lost at sea.
His First Few Days
For the first few days, Callahan had to think about what he could do to make sure he survived until help came. Since he had tethered his lifeboat to the Napoleon, he could swim back and forth between the two in order to get some other supplies like a sleeping bag, a cushion, and an emergency kit that held a survival kit. It was going to come in handy.