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Can shipwrecked men survive if they drink sea water?
Bombard’s voyage was a truly remarkable exhibition of fortitude and an impressive demonstration of the capacity of the human body to withstand abuse. However, several shipwreck survivors, less well prepared than Dr. Bombard, have made longer drifts.
The longest drift on record is that of Poon Lim, a native of Hong Kong, who spent 133 days on a raft in the South Atlantic after his ship, the S.S. Ben Lomond, was torpedoed in 1942.
Poon Lim spent the first hour after the torpedoing floating in his life jacket. Then he had the good fortune to reach an unoccupied raft. The raft had food and water for 50 days—but the last 83 days of his drift he subsisted on rain water and fish. Brazilian fishermen picked him up, still in good physical condition after 133 days on his own.
Has the survivor no choice but to rely on rain water as Poon Lim did, or take a chance on sea-water poisoning as Bombard did? Fortunately, most survivors of ditchings or shipwreck will not be limited to these alternatives. Two devices developed during World War II give today’s survivor a margin of safety—the desalting kit and the solar still.
The desalting kit provides a method of converting salt water to fresh in practically any weather, but it can be used only once. The solar still functions only when the sun is shining or under a light cloud cover, but it can be used indefinitely.
The desalting kit precipitates dissolved salts in sea water so that they can be filtered out. Each desalting kit contains a number of briquettes of silver aluminum silicate and a plastic processing bag. Each briquette will desalt about a pint of water. The kit will produce six or seven times as much water as could be carried if the same space were used to carry canned water.
In use, the processing bag is filled with sea water up to a marked line and the briquette dropped in. The bag is kneaded and agitated gently for an hour, allowing the briquette to break up and the chemical reaction to take place. Desalted water is drawn off through a filter in the bottom of the bag, from which it can be drunk directly or squeezed into a storage bag.
The solar still is a spherical plastic envelope that can be inflated either by mouth or by using the pump carried on most life rafts. Inside the sphere is stretched a black cloth, upon which sea water drips from a reservoir. The sun heats the moist black cloth, and from it the water evaporates—fresh. The evaporated fresh water condenses on the inner surface of the plastic sphere in small drops, which run down to the fresh-water trap at the bottom of the still. The salt stays in the black cloth.