As seen from the Orlando Sentinel (03.17.07):
Last week a man jumped from the back of a cruise ship and was found adrift 8 hours later. Michael Mankamyer, 34, fell 60 feet off the back of the Carnival Glory and drifted about 20 miles with the Gulf Stream in 70 degree water. Officials are not really sure how he survived for 8 hours in the open sea. "It's pretty miraculous that he's still alive," said U.S. Coast Guard Petty Officer 1st Class Dana Warr. "It's not that it doesn't happen, but it's few and far between when we're trying to find someone that jumps from a cruise ship." The reason most people do not survive is because they are usually overcome by hypothermia and drown. According to Richard Rotundo professor at the University of Miami's Miller School of Medicine, “ His 300 pound girth might have helped. As a heavyset man, he was more likely to float than someone leaner.” The professor continues, "Someone who is really overweight and has excess fat, their body density would be less than water. Layers of fat also would insulate Mankamyer from the water.”
When lecturing, I used to say the sole function of fat is to insulate. I have been proven wrong. Fat has a secondary function of acting as a floatation device. So when falling off the back of a cruise ship, make sure you have the proper floatation device to secure you in the choppy waters.