Dehydration is a lack of water in the body's tissues, upsetting the balance of electrolytes in the blood. Mild dehydration is relatively common and not serious, but severe or chronic dehydration can be a life-threatening problem. Lack of water can damage the kidneys, for example.

Symptoms of mild dehydration are increased thirst and dry mouth - symptoms common with many other ailments. The skin may wrinkle due to the lack of water. As dehydration gets more severe, blood pressure decreases, episodes of confusion or coma may occur, and urination may be infrequent or not occur at all.

Dehydration can result from diarrhea, excessive sweating, or simply by ignoring thirst and not drinking sufficient water (especially when coupled with hard or prolonged exertion or exposure to the elements).

Bottom line for sailors: dehydration can be serious, but you can treat it yourself. If you're thirsty, drink! Especially during a blow, watch your fluid intake.