From Skeletons on the Zahara: A True Story of Survival, by Dean King (Little, Brown, 2004), Kindle pp. 77-78:
It is said that to a thirsty man in a boat, sea spray is a constant torment. It taunts him in its plentitude. It beads on his brow and runs down into his mouth, only to make him thirstier. Inevitably, some of the crew began to crack. A couple of them indulged their increasing fascination with death by leaning over the gunwale and submerging their heads, claiming that they wished to taste what was sure to be their fate.
The stages of dehydration would be categorized a century later by W. J. McGee, a notable amateur thirst-researcher and director of the St. Louis Public Museum. His portrait of the process of human dehydration, which has become the sine qua non of the field, shows five distinct phases: clamorous, cotton-mouth, swollen-tongue, shriveled-tongue, and blood-sweat, each roughly equivalent to a 5 percent decrease in body weight. The Commerces [sailors from the shipwrecked Commerce] had long since grown clamorous: uncomfortable, irritable, feverish. Their stale throats cracked when they spoke. Their fat, sore tongues restricted conversation to terse phrases, and they slurred or lost words. Their hearing had grown muffled, due to loss of moisture in the inner ear. In the cotton-mouth stage, the mind increasingly distorts reality and desires. Sufferers rashly toss off clothes or possessions or, in the case of the Commerces, become obsessed with how it would feel to die in the sea. It is normal for spells of feverish dreams to focus on the urge to drink, and the Commerces, parched beyond imagination and penetrated by salt, extolled the lush banks of the Connecticut River and craved a cup—or a barrel—of the delicious mineral water from the freshets that filled it. In his head, Riley built and rebuilt the stately spa he had dreamed of.
That afternoon, Riley gave up any hope of a rescue at sea. To continue on meant certain death, roasting on the woeful collection of planks that formed their boat, now an inhuman prison cell that confined their bodies in cramped agony. They might fight on another handful of days, but they did not have enough food and water to maintain their strength. They would soon lose the power to affect their fate.