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Survival at sea is primarily decided by the availability of drinking water. Our body needs to consume roughly one-half gallon of fresh water daily to maintain healthy body functions.
Without fresh water, the average person can live for only a few days; somewhat longer under comfortable conditions. It is possible to survive a week under extreme circumstances, but essential organs are often sacrificed during such ordeals of extreme dehydration.
An easy way to remember survival parameters is by the Rule of Threes. Death can occur in:
Drinking alcohol for survival when a fresh water supply is low is worse than not drinking at all because alcohol causes excessive urination and the body loses more water than normal to purge its cells.
But there is nothing worse than drinking salt water.
Physicians and biologists back in the 1950s attempted to cross the Atlantic without supplies of food and drinking water, solely to prove it could be done while consuming only seawater. The most noted was Dr. Alain Bombard who departed from France in an unpowered 15-foot inflatable boat.
Upon reaching Barbados after 65 days adrift, he claimed to have survived without a freshwater supply, having lived solely on caught fish and plankton. Soon after, a German physician named Dr. Hans Lindemann went to sea (adrift) to disprove Bombard’s claim of living on seawater. (He also suspected Bombard of having a stash of freshwater but this accusation could not be proven.)
Most believe Lindemann was correct, demonstrating that ingesting fresh water from consumed fish was insufficient for survival and that drinking seawater would exacerbate the problem. Lindemann nearly died during his extended drift.
General acceptance is that seawater can be consumed but must be accompanied by three parts freshwater mixed with less than two parts salt water. Consumption of straight salt water will definitely kill you soon.
Seawater contains roughly 3.5 percent salt and 96.5 percent water. Our kidneys separate waste material in the blood and store it as urine in the bladder, but kidneys cannot make urine from liquid with a concentration of more than 2 percent salt.
With this saline overload, the kidney must extract water from other cells in our body to dilute the excess salt, and this causes dehydration. Yes, the more salt water we drink, the thirstier we become and the more dehydrated as well.
Drinking urine is not a solution either, as it contains the excess salt your body is trying to expel. The kidneys eventually fail to rid our blood of salt and concentrations rise to toxic levels. Our nervous system becomes short-circuited from the electrolyte imbalance, seizures begin and cardiac arrhythmia leads to death.
An analysis of records from 163 separate life raft voyages (extended strandings) documented that 39 percent of sailors who drank seawater experienced death during or soon after their drift, whereas the risk of near-term death was only 3 percent for those who did not ingest seawater.
These numbers may have been biased according to the duration of the strandings (e.g., fewer deaths for short strandings when survivors could exist without fresh water) but the 10-fold difference in death statistics is significant.
All manuals for Survival at Sea strongly and wisely warn against drinking seawater. It is noteworthy that the manual for Marine Combat Water Survival of the U.S. Marine Corps specifies the following rules for sailors stranded at sea:
Definitely worth remembering as you check your life raft and survival gear.
Scott E. McDowell has a doctorate degree in ocean physics, is a licensed captain and author of Marinas: a Complete Guide, available at www.scottemcdowell.com. Comments are welcome at firstname.lastname@example.org.