How Long Can a Person Survive at Sea Without Water?

Lifeboats can help people flee sinking or burning ships but they are no guarantee of survival.

Survival at sea is one of the most traumatic and taxing experiences a person could undergo. The most critical issue is finding sources of water, because seawater has negative effects on the human body. Without fresh water to stay hydrated, a human being can last about 24 hours without suffering severe physical symptoms, with death almost certainly ensuing between 24 and 72 hours without a source of water.

Survival

There are three usual options for survival at sea without water: drinking recycled water in urine, ingesting water and moisture by consuming fish and other sea-life and drinking rainwater. Fresh, non-saline rainwater is the most desirable source of water if there are no other options.

Heat

Heat is perhaps the biggest factor that affects dehydration and causes the lack of water to be more acutely felt. In the open ocean, there is no shielding from the elements other than the cloud cover, and the constant heat from the sun means that a person would need more water than normal to stay hydrated.

Saltwater

Saltwater is undrinkable by human beings and, in large enough quantities, can exacerbate dehydration due to salt content. At the very worst, saltwater can cause renal (kidney) failure, due to overloading the organ with impurities and toxins that it is meant to filter. This is a particularly painful death, when untreated.

Physiological Effects

Dehydration has a powerful effect on the body, as the lack of water will damage the mucous membranes, increase your heart rate, sap your energy, cause vomiting and diarrhea. Eventually, it can cause auditory and visual hallucinations as well as severe headaches, due to the shrinking of the brain.

References

• Guardian UK: How long can someone survive without water?
• Survival Topics: How Long Can You Survive Without Water?