How long a person can survive in cold water depends on many factors, including water temperature, body size and composition, clothing, and water movement. When exposed to very cold water, the body undergoes profound physiological changes that can result in hypothermia, unconsciousness, and even death if not treated promptly. However, with the proper preparation, training, and equipment, it is possible to survive for extended periods in cold water. This article will examine the key factors that impact cold water survival times and provide tips for maximizing your chances.
What Happens to the Body in Cold Water
Within the first minute of cold water immersion, the body automatically gasps uncontrollably as a response to the sudden temperature change. This is extremely dangerous, as water can be involuntarily inhaled, increasing the risk of drowning. After this initial shock response, the body will begin to direct blood flow away from the extremities and towards the core organs in an attempt to conserve heat, a process known as peripheral vasoconstriction. Shivering soon follows as the body tries to generate extra heat through muscle contractions. While shivering does produce heat, it also leads to faster breathing and increased heart rate, using up limited energy reserves.
After about 30 minutes in cold water, the body’s shivering response becomes much less effective. Small muscle groups may become paralyzed as nerve transmission becomes interrupted. Larger muscles soon follow. When the body core temperature drops below 95°F, amnesia and loss of judgement can occur as brain function becomes impaired. Victims may become disoriented and unable to keep their airway clear of water. As core temperature continues to drop, unconsciousness and cardiac arrest eventually result. Death can occur as quickly as one hour after initial immersion in extremely cold water.
Key Factors That Affect Cold Water Survival
Water Temperature
Water temperature is the most significant factor impacting survival time in cold water immersion incidents. Even moderate decreases in water temperature lead to markedly faster cooling and hypothermia onset. Some general survival time estimates based on water temperature are:
| Water Temperature | Likely Survival Time |
| Below 32°F (0°C) | Under 15 minutes |
| 32-40°F (0-4°C) | 15 – 30 minutes |
| 40-50°F (4-10°C) | 30 – 60 minutes |
| 50-60°F (10-15°C) | 1 – 2 hours |
| 60-70°F (15-21°C) | 2 – 7 hours |
| Over 70°F (21°C) | Indefinite |
In water colder than 50°F, hypothermia will eventually set in, although survival times can vary drastically based on other factors. Water colder than 32°F leads to a complete incapacitation of muscles in most individuals within 15 minutes. However,prepare documentation and very fit swimmers have survived over an hour in water as cold as 28.5°F wearing special protective clothing. Normal body temperature drops 2-4 times faster in cold water versus cold air exposure.
Body Size and Composition
People with more body fat and insulation tend to fare better in cold water survival situations. Women generally have a higher percentage of body fat compared to men and thus survive cold water immersion longer on average. Obese individuals and children cool more slowly due to their greater fat layer insulation. Very muscular or thin individuals with little body fat cool rapidly and are at high risk for life-threatening hypothermia. Survival times are markedly decreased for underweight individuals.
Clothing Insulation
The type of clothing worn in cold water significantly affects heat loss and survival time. Even routine clothing like jeans, sweaters, and light jackets can provide enough insulation when submerged in cold water to extend survival by up to 20-30 minutes. Wetsuits trap a thin layer of water between the suit and body. Since the thermal conductivity of water is 25 times greater than air, this thin trapped layer provides significant insulation. With heavy-duty drysuits or survival suits, designed to keep the wearer completely dry, survival times of several hours in near-freezing water are possible. However, clothing that fits tightly against the skin provides minimal insulation when wet. Any air trapped in clothing is soon lost after submersion.
Water Movement
Heat is lost much more rapidly in moving water compared to still water due to greater convection cooling. Wind chill does not apply in the water, but movement against currents or waves dramatically accelerates heat loss. Treading water or swimming increases heat production through muscular activity which temporarily raises body temperature, but this effect is trivial compared to the increased cooling. Floating as motionless as possible maximizes cold water survival time.
Body Position
The position of the body in cold water significantly affects heat loss. Heat is conducted away from the body about 25 times faster when the body is submerged up the neck versus just the legs due to the head’s high surface area to volume ratio. The most heat is lost through the head, neck, armpits, chest, and groin. Adopting a position that exposes the least amount of these critical areas, such as the Heat Escape Lessening Posture (HELP), can extend survival time. In this hunched position, arms are kept folded across the chest and thighs are pressed together.
Age
Children cool more slowly than adults in cold water due to their favorable surface area to body mass ratio. However, infants have minimal insulating fat and experience rapid heat loss. Older adults also have lower muscle mass and reduced shivering response leading to quicker hypothermia onset. Middle-aged, healthy adults tend to have the best cold water survival rates. However, cases of extreme cold water survival have occurred across the age spectrum.
Body Fat Percentage
Individuals with greater amounts of body fat fare better in cold water due to the excellent insulating properties of adipose tissue.Women, who naturally have a higher percentage of body fat compared to men, can survive approximately 30 minutes longer on average in cold water when wearing minimal clothing. However, lean muscular individuals with little body fat cool rapidly and are at high risk of early hypothermia and drowning. Even modest fat layers provide useful insulation and buoyancy.
Activity Level Before Immersion
Engaging in physical activity immediately before cold water immersion leads to faster cooling and reduced survival time. Exercise elevates metabolic rate and increases blood circulation to muscles. This means more blood flow is directed to the periphery, away from the core, when first immersed. Resistance to hypothermia is reduced after physical exertion. However, moderate activity before immersion may help raise body temperature slightly.
Body Type
Individuals with a tall, slender body type cool faster than those with a short, stocky build. A high surface area to volume ratio allows for greater heat loss. Shorter limbs like those seen in some ethnicities also reduce surface area and improve cold water survival potential. A compact, stocky body build helps slow heat loss. However, muscle mass does not impact heat loss nearly as much as the thickness of the insulating fat layer.
Maximizing Cold Water Survival
To maximize your survival time during unexpected cold water immersion, follow these key tips:
– Wear layered, insulating clothing made of wool or synthetics. Bring extra clothing in case primary layers get wet.
– Put on a head covering to protect your high heat loss head and neck area.
– Avoid swimming or unnecessary movement in the water which increases convective heat loss. Float as still as possible.
– Adopt a body position that reduces exposure of high heat loss areas like the neck, armpits and groin. Use the Heat Escape Lessening Posture (HELP).
– Get as much of your body out of the water as possible. Climb on top of floating debris or tread with your arms.
– Huddle together with others in the water to reduce exposed surface area. Avoid splashing which speeds heat loss.
– Keep a positive attitude and remain calm. Panic leads to fast breathing and increased heat loss.
– If wearing a lifejacket, do not overinflate it as this can compress the body core and increase heat loss.
– Get out of the water as soon as possible, even if feeling hypothermic. You can rewarm much faster out of the water.
– If experiencing hypothermia, handle very gently and get emergency medical treatment.
Special Considerations for Cold Water Survival
Rescue Breathing
Performing mouth-to-mouth rescue breathing in cold water is difficult and provides minimal insufflation. Instead, provide stimulation by rubbing the victim’s chest and gently slapping their face while retrieving them from the water as soon as possible. CPR should be started once on shore.
Cold Water Boot
After hypothermic drowning victims are rescued from cold water, some may experience a gasping “return to life” known as the cold water boot. Handle these victims very gently and immediately begin full CPR resuscitation. The cold water boot does not indicate full recovery from hypothermia.
Swim Failure
Within minutes of cold water immersion, muscular strength and coordination dramatically decline. Attempting to swim risks drowning through swim failure. Floating while wearing a lifejacket maximizes survival. Treading water should only be attempted if flotation is immediately available.
Conclusion
Surviving prolonged cold water immersion requires preparation, insulation, flotation, and an understanding of body heat loss. While individual physiology affects tolerance, proper clothing and body positioning can extend survival time by over an hour in near-freezing water. However, emergency assistance should still be summoned immediately in any cold water scenario. By anticipating and preparing for the profound effects of cold water exposure, the likelihood of surviving a cold water accident can be dramatically increased. The key is maintaining body heat for as long as possible until rescued.