ON THIN ICE!
Surviving a plunge into frigid waters
In the winter, northern regions with lots of water features become vast fields of ice. Because the shortest distance between two points is a straight line, you might be tempted to cross that frozen lake rather than go around it. That’s fine if the ice is thick; but, if it’s not, there’s a risk of falling through the ice. If so, you’ll be in extremely cold water (and extremely big trouble). How thick must the ice be to sustain the average person’s weight? At least 4 inches for any reasonable activity such as walking or cross-country skiing. On a snowmobile or all-terrain vehicle, at least 5 to 6 inches would be required. Always stay off ice that’s thought to be 3 inches thick or less, especially on warmer days, when ice might be thawing. Note that sea ice is weaker and requires a greater thickness to support the same weight as fresh-water ice.
HOW YOUR BODY LOSES HEAT
Your body has various methods it uses to keep its internal core temperature at appropriate levels. The “body core“is composed of the major internal organ systems that are necessary to maintain life, such as your brain, heart, liver and others. A drop in the body’s core temperature of just 4 degrees (F) below normal might cause ill effects due to the cold—a condition known as “hypothermia.” In cold weather, your blood vessels constrict involuntarily to conserve heat. Muscles “shiver” as a method of heat production. As well, you can voluntarily increase heat with exertion; that’s why it’s recommended to “keep moving” in cold environments. When the body is exposed to severe cold, as in the case of a fall through the ice, it’s difficult to maintain a normal core temperature. Cold water, because it is denser than air, removes heat from the body via a process called “conduction.” Water “conducts” heat away from the body much faster (some say 32 times faster!) than air does. The higher the percentage of body surface area that is submerged, the faster it loses heat.
THE "1-10-1 PRINCIPLE"
The U.S. Coast Guard 1-10-1 Principle gives us a sobering glimpse regarding your prospects if you have to spend time in icy cold water: • 1 minute—you have one minute to gain control of your breathing. • 10 minutes—you have 10 minutes to realistically help in your own rescue. Cold temperatures will cause loss of sensation and motor control of muscles, leading to what is known as “swim failure.” After 10 minutes, victims without a life jacket will drown. • 1 hour—you have one hour, more or less, before hypothermia renders you unconscious. One major factor is, of course, the water temperature. Another variable in a person’s survival is the amount of body fat the victim has. Body fat helps conserve heat and might increase the time interval before the patient becomes hypothermic. Take the example of passengers on the Titanic. Unless there was an available seat on a lifeboat, they ended up in 40 degree (F) water. Within 10 minutes, they were likely unable to help themselves in any significant way.
THE TORSO REFLEX
When a person falls through the ice, they experience a physiological reaction known as the “torso reflex,” sometimes called the “inhalation response.” When the body is suddenly immersed in temperatures below 70 degrees (F), the torso reflex causes the victim to involuntarily gasp. This reaction is meant to increase oxygen intake into the lungs and increase metabolism to build internal warmth. When the head is below the surface, however, the sudden urge to breathe causes water to be inhaled instead of air. When this happens, airways can go into spasm, causing the disoriented victim to panic. Coupled with a massive release of adrenaline, as well as sudden
ALWAYS STAY OFF ICE THAT’S THOUGHT TO BE 3 INCHES THICK OR LESS, ESPECIALLY ON WARMER DAYS, WHEN ICE MIGHT BE THAWING. NOTE THAT SEA ICE IS WEAKER AND REQUIRES A GREATER THICKNESS TO SUPPORT THE SAME WEIGHT AS FRESHWATER ICE.
changes in heart rate and blood pressure, many lose the ability to perform the actions that might save their lives. Although some aspect of the torso reflex occurs in just about everyone who is immersed in cold water, the response seems to be variable among individuals. Immersions involving the face seem to be the most severe. Some outdoorsmen who regularly kayak in northern waters appear to be affected less often. This might be due to acclimation to the cold or experience with multiple “dunkings” over time.
FALLING THROUGH THE ICE
Certainly, a fall through lake ice can be life-threatening, but your chances of surviving are much greater if you know what to do. If you can keep it together mentally, a few simple steps might save your life. Stay calm: The shock of a sudden immersion in cold water makes it difficult to think, as well as breathe. In some circumstances, you might realize the ice is going to break under your weight. Faced with this, it’s important to brace yourself and try not to inhale water if you go under. This will be difficult, but it is more possible if you have some warning that a dunking is imminent.
WHEN THE BODY IS EXPOSED TO SEVERE COLD, AS IN THE CASE OF A FALL THROUGH THE ICE, IT’S DIFFICULT TO MAINTAIN A NORMAL CORE TEMPERATURE ... THE HIGHER THE PERCENTAGE OF BODY SURFACE AREA THAT IS SUBMERGED, THE FASTER IT LOSES HEAT.
Torso reflex might be prevented by covering your mouth and nose with your hands before getting immersed. If you can establish the “seal” as you enter the water, you’ll have a better chance of not drowning. This procedure should be taught to everyone spending time in proximity to cold water and should be maintained until the head is above the surface. Make every effort to keep calm. You have a few minutes to get out before you succumb to the effects of the cold. Panic is your enemy. Get your head out of the water: This is best accomplished by breathing in and bending backward as soon as you get your head out of the water. If there are others nearby, shout that you’re
in need of emergency aid.
Get rid of heavy objects that weigh you down: The more you weigh, the harder it will be to get your body out of the water. Tread water and turn: Treading water by kicking with your legs will help raise you farther out of the water. Quickly turn your body in the direction you came from—you know the ice was strong enough to hold you there. Try to lift up out of the ice: Place your arms on the ice and spread them widely apart in front of you. Kick with your feet to give you some forward momentum and try to get more of your body horizontal and out of the water. Lift a leg onto the ice, and then lift and roll out onto the firmer surface. Do not stand up: Keep rolling in the direction that you were walking before you fell through. This will spread your weight out instead of concentrating it on your feet. Then, crawl away until you’re sure you’re safe. Get warm as soon as possible: You’re out of the water—but you’re not out of the woods! Get to a warm place if possible. Hypothermia is highly likely, and soaking-wet clothing isn’t helping. Having spare clothes or a blanket available in a hiking partner’s backpack is an important consideration. So is having a way (or two or three) to start a fire if no heat source is at hand. Changing into dry clothing should be done immediately and before starting a fire: External heat sources aren’t very effective in penetrating wet clothing. It’s possible that you might have to change outdoors. If so, stay out
A DROP IN THE BODY’S CORE TEMPERATURE OF JUST 4 DEGREES (F) BELOW NORMAL MIGHT CAUSE ILL EFFECTS DUE TO THE COLD—A CONDITION KNOWN AS “HYPOTHERMIA.”
of the wind by standing behind a large tree or some other barrier. Once you have access to a heat source, get close enough to feel the warmth and bring your knees to your chest with your legs tightly together. This will help conserve body heat. Have others share body heat with you if possible.
Of course, an ounce of prevention is worth a pound of cure. Avoid situations where visibility might be reduced, such as traversing frozen lakes at night or during heavy snows. Even in conditions that afford good vision, stay clear of unfamiliar terrain. Any backcountry travel plans should be shared with others who can send for help if you don’t reach your destination or if your return is overdue. This is good policy in any season. Once you are on the ice, see if there are any cracks or abnormal surfaces. The strength of the ice is not the same everywhere on the same body of water. Beware of flowing water at the
edges, springs underneath and ice that has thawed and refrozen. Although by no means can ice safety be guaranteed on sight alone, the colors of the ice might give you a clue: Blue/clear Ice: This ice is thought to be the highest density, but it is only safe if it is 4 or more inches thick. White/opaque Ice: Snow freezes and forms a second layer above the main body of ice. This ice is often weak due to air pockets between layers. Snow can also act as an insulator and warm up the ice, thus weakening it. Mottled Ice: This ice is unsafe due to thawing and deteriorating at the center and base. Gray or Black Ice: This is low-density, melting ice. It is unsafe.
MAKE EVERY EFFORT TO KEEP CALM. YOU HAVE A FEW MINUTES TO GET OUT BEFORE YOU SUCCUMB TO THE EFFECTS OF THE COLD. PANIC IS YOUR ENEMY.
h Ice should be 8 to 10 inches thick for a car to safely drive on it.
i Right: Think twice before traversing a frozen lake, because that shortcut might be dangerous.
i Right: Mottled ice is unsafe to travel on due to thawing and deteriorating at the center and base.
h Left: Travel in the cold can induce hypothermia.
h Below, left: Once out of the water, work to get warm immediately. h Below, right: A victim can easily get disoriented and might not survive a fall through the ice.
h Above: After an immersion, change out of wet clothes as quickly as possible and drink something warm.
i Right: Full body immersion in cold water leads to sudden and possibly dangerous effects. While some people do it recreationally, they should never do this alone. i Bottom: A partner with a length of rope can save your life.
h Left: A capsized raft could mean death in cold waters. h Above: Transport the victim out of the cold as quickly as possible after their exposure to icy water.