The raft drifted westward with the
South Equatorial Current and the trade winds. After exhausting the meagre food supplies he had salvaged from the sinking sloop, Callahan survived by "learning to live like an aquatic caveman". He ate primarily
mahi-mahi as well as
triggerfish, which he speared, along with
flying fish, barnacles, and birds that he captured. The sea life was all part of an
ecosystem that evolved and followed him for 1,800 nautical miles (3,300 km) across the ocean. He collected drinking water from two
solar stills and various improvised devices for collecting rainwater, which together produced on average just over a pint of water per day. There was a third solar still; however, because the stills he had were an early World War II prototype without supplied instructions, Callahan had to cut and destroy one of the stills to
reverse-engineer how they worked. Nevertheless, these stills surely saved Callahan's life. Callahan's use of a radio beacon and many flares did not trigger a rescue.
EPIRBs were not monitored by satellites at the time, and he was in a part of the ocean that was too isolated for the signal to be heard by aircraft. Additionally, ships did not spot his flares. While adrift, he spotted nine ships, most in the two
sea lanes he crossed; however, from the beginning, Callahan knew that he could not rely upon rescue but instead must, for an undetermined time, rely upon himself and maintaining a shipboard routine for survival. He routinely exercised, navigated, prioritized problems, made repairs, fished, improved systems, and built food and water stocks for emergencies. ==Rescue==