ST. PETERSBURG, Fla. (AP) — The U.S. Coast Guard rescued a commercial fisherman who was clinging to a cooler in the Gulf of Mexico after his boat capsized, the day after evacuating a boy and his father from the same vessel.

The agency received an emergency alert at 8:56 a.m. Thursday from the Jenny Lynn, broadcasting its location, according to a news release.

A MH-60 Jayhawk helicopter crew dispatched from Air Station Clearwater found Robert Heart, 48, clinging to a cooler in 3 to 4-foot (1-1.2 meter) seas. He was still near the 36-foot (10.9-meter) boat, which was almost entirely under the surface.

A rescue swimmer helped Heart into a cage that was hoisted into a helicopter, whose crew took him to a Tampa hospital for a medical evaluation. His condition was not immediately known.

Heart had declined help a day earlier, when the Coast Guard Cutter Diamondback responded to the Jenny Lynn to medically evacuate a 15-year-old boy who had fallen ill onboard. That crew took the boy and his father to the Sector St. Petersburg base.

Heart told the crew Wednesday that the boat was no longer working under its own power and that a sister vessel was on its way to help.

The Coast Guard is now investigating what went wrong on the boat’s ill-fated trip.