Why do you say that , how did you reach that conclusion (your math)?
Seems to me its very similar to
Tourists swim 14 hours after boat sinks - ETS Forums 8 miles from land, swim for 14 hours, warm water (above 70 farenheit)
This guy is 6'3" 250lb, water temp was 75, swam 9 miles for 10-12 hours ...
Rob Konrad: Former Miami Dolphin falls off fishing boat, swims 9 miles to shore, Coast Guard says - wptv.com
left the Hillsboro Inlet in Deerfield Beach around 10:30 a.m. Wednesday and that around 1 p.m. he tripped and fell overboard as his 36' Grady White boat was on autopilot to the Bahamas.
Palm Beach police Konrad reached land at 4:42 a.m. Thursday. He approached a gate in the 1800 block of South Ocean Boulevard and met with an officer working an off-duty detail.
Even long distance swimmers say Conrad's swim for survival is amazing.
"2:30:10 I'm very impressed. Extremely impressed. Can you imagine keeping your face in the salt water for so long - that alone would really wreck on him and then you have salt water going into your mouth which swells your mouth and tongue," swim coach Chazz Chiamardas said.