Topic: Cold Water Dangers Posted: 21 Dec 2008 at 2:18pm
From the ACA: http://www.americancanoe.org/safety/coldwater.lasso
Often the best paddling opportunities exist in the spring and fall,
when cooler weather and cold water increases the risks associated with
getting wet. ACA believes that all paddlers should take the necessary
precautions to be able to safely enjoy canoeing, kayaking and rafting
under these conditions. It is essential that you carefully read and
follow the advice below to increase your odds of survival should you
capsize or encounter bad weather.
Cold Shock is a dangerous, sometimes fatal, condition that
can result when a person is suddenly immersed in cold water, such as
would occur in a capsize. The sudden exposure of the head and chest to
cold water typically causes an involuntary gasp for air, sudden
increases in heart rate and blood pressure, disorientation and can
possibly cause cardiac arrest.
Hypothermia is a dangerous and often-fatal condition that
results when exposure to cold temperatures causes the body to no longer
be able to maintain its normal temperature in the core region (heart,
lungs, etc.). While this condition can occur through exposure to cold
air alone, its onset is much faster when the body is wet or immersed in
water. Paddlers must take special care to protect themselves from this
danger any time they paddle in cold water, rainy conditions, or cool
air temperatures.
To reduce the exposure to these hazards:
Dress in layers using synthetic fabrics such as polyester
fleece to prevent getting overheated or chilled from perspiration.
Avoid wearing cotton clothing when paddling in cool or cold
temperatures.
Carry a waterproof jacket designed for splash and/or rain protection.
You should always wear a wet suit or dry suit 1) if both the air
temperature and water temperature are below 60 degrees Fahrenheit, 2)
if you will be far from shore on cold water, or 3) anytime in cool or
mild weather when you expect be repeatedly exposed to cold water. Keep
in mind that the best type of wetsuit for paddling is the "Farmer john"
style, and that the warmth and comfort range of a dry suit can be
flexible based on the clothing worn underneath it.
Wear a warm hat that will stay on your head in the water. A fleece-lined skullcap is ideal.
Have spare dry clothing and store in a sealed dry bag while on the
water and, if wet, change into dry clothing at first signs of
shivering.
Test your protective clothing in a controlled cold water environment to understand the level of protection provided.
Know the water temperature before you set out. Please recognize that
dam released water can be significantly colder than expected.
Always wear your lifejacket (PFD).
Paddle near to shore and/or near others who can help you in the event of capsize.
Keep your body well fueled with high carbohydrate foods and lots of water.
In the event of a capsize in cold water:
Get out of the water and dry off as quickly as possible.
Once you are out of the water, put on dry clothes.
If you are unable to exit the water quickly, keep calm, remain with
your boat, conserve energy and get in the H.E.L.P. (heat escape
lessening posture) position - fold your arms against your chest, cross legs, and keep still until help arrives.
If 2 or more people are in the water, get into the "Huddle" posture - put your arms around one another, stay close together, and keep still.
Only attempt to swim to shore if 1) the is little or no chance of
rescue 2) you are in danger of floating into dangerous rapids or other
hazards, 3) you are absolutely certain you can make it.
Note:Any decision to swim for shore should not be entered
into lightly. Physical activity such as swimming, or other struggling
in the water increases heat loss. Survival time can be reduced to
minutes. Strong swimmers have died before swimming 100 yards in cold
water. In water under 40 degrees farenheit, victims have died before
swimming 100 feet. Also keep in mind that judging distance accurately
on the water is difficult.
The Symptoms of Hypothermia
The most typical symptoms of hypothermia are listed below in the general order of onset.
Shivering
Impaired Judgment
Clumsiness
Loss of Manual Dexterity
Slurred Speech
Inward Behavior, Withdrawal
Shivering Stops
Muscle Rigidity
Unconsciousness
Treatment of Hypothermia
Mild hypothermia (victim shivering but coherent):
Move victim to place of warmth. Remove wet clothes, give warm, sweet
drinks; no alcohol or caffeine. Keep victim warm for several hours.
Moderate hypothermia (shivering may decrease
or stop): Victim may seem irrational with deteriorating coordination.
Same as above but no drinks. Victim should be kept lying down with
torso, thighs, head and neck covered with dry clothes, coats or
blankets to stop further heat loss. Seek medical attention immediately.
Severe hypothermia (shivering may have
stopped): Victim may resist help or be semiconscious or unconscious).
Removed from water, victim must be kept prone, on back and immobile.
Victim must be handled gently. Cover torso, thighs, head and neck with
dry covers to stop further heat loss. Arms and legs must not be
stimulated in any manner. Cold blood in extremities that suddenly
returns to the core may induce cardiac arrest. Seek medical attention
immediately.
Victim appears dead (little or no breathing
or pulse, body rigid): Assume victim can still be revived. Look for
faint pulse or breathing for 2 minutes. If any trace is found, do not
give CPR. It can cause cardiac arrest. Medical help is imperative. If
pulse and breathing are totally absent, trained medical personnel
should start CPR.
Acknowledgments: This article was adapted from information
in the ACA video Cold, Wet and Alive, and from the article Off-Season
Boating, Cold Shock, and Hypothermia by Charles A. Sutherland, Ph.D.
Note:Any decision to swim for shore should not be entered
into lightly. Physical activity such as swimming, or other struggling
in the water increases heat loss. Survival time can be reduced to
minutes. Strong swimmers have died before swimming 100 yards in cold
water. In water under 40 degrees farenheit, victims have died before
swimming 100 feet. Also keep in mind that judging distance accurately
on the water is difficult.
Leif your Navy example has to do w/ computer generated report on coldwater effects on peoples body temps while wearing different types of layers including drysuits. The report does not say anything about the survival time of someone swimming or struggling in water.
"For each subject, water temperature, and clothing configuration, predicted Tre was computed and a predicted time to fatality was determined. According to THTM, fatality time represents the point at which the body is unable to generate sufficient internal metabolic heat for survival."
Also: "However, since it was not known what the “real” wave effect on head insulation value should be and it was not feasible to repeat or add trials, it was decided to present the data as they are, representing the uncontrollable nature of open-water turbulence."
I'd imagine someone in drysuit could "survive" for 30 minutes but how actively could they actually participate in their own survival, especially swimming in rapids?
It would be a pretty neat experiment to see just how well people could function wearing a drysuit in icy water. I'd be down to try it out if someone has a new drysuit I could use.
It's interesting that people w/ more fat have a longer survival rate than lean individuals...think I'll have another beer and call it "coldwater conditioning".
Wonder what the effects are on your brain of flipping over in cold water? Think if you got recircted in a hole for a while, swam, you wouldn't have any loss of brain function? Curious what sort of decreased functioning this creates, anyone know?
Also wearing a drysuit presents an entirely new danger:
"Submersion injury complicated by hyperthermia in a kayaker wearing a drysuit"
This is actually a pretty crazy story. Where a guy was paddling in cold water and ended up getting hyperthermia he was pinned and rescued in cold water. The doctors left the dry-suit on thinking it was keeping him warm and ended up his temp rose to over 107. Could be good to know if anyone ends up taking a paddling buddy to the hospital.
"The model does not predict for females who are known to lose more body heat than men, and also does not account for wave effects, fatigue, last mealtime, injuries, attitude, etc., which also compromise survivability."
When I went through SRT training they were saying that the environment inside a drysuit without extra layering will be 10% warmer than the outside air.
Thanks for putting that technical data out there, paul.
For the record each one of us essentially "complied" with each of those bullets you listed under the ACA's recommendations to "reduce exposure to these hazards" when we went out on saturday.
I was SO warmly dressed that I'm confident that under those specific conditions, in that specific place, I could have EASILY swam to shore before any major heat loss occured. My hands would have gotten VERY cold in the process though, I'm sure. I was only wearing pogies, which only keep my hands warm while I'm holding my paddle.
Granted, If I got pinned, or knocked unconcious, it may be a totally different story. That's why it's important to use more caution while you're out in such conditions.
On a river you know like the back of your hand, it's pretty feasable to stay out of trouble if you exorcise caution and pay attention. Maybe take easier lines than you would, give obstacles a wider birth than you normally would, maybe even paddle around whitewater features that are likely to splash you and get you wetter.
But one needs to know for certain they can navigate the stretch they are going to paddle without capsizing. It's common sense. Simple common sense. It can be very rewarding to paddle in winter conditions. Just be prepared and use good judgement.
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