To build on the above, in 2006 I wrote the following for our local paddle club.
It's lengthy but may convince someone not to go "out there" to begin with when knowing the water temperature is below 60*F. Also, note trying to swim, even
w/PFD, and close to shore may be futile.
Oh, if you think C-Dory owners, or any other boat owner, should ignore this
because they don't think they are paddlers, think again...
Aye.
_____________________________________
COLD SHOCK - INFORMATION TO HELP KEEP PADDLERS SAFE
Martin Strand III (aka Foggy)
March 22, 2006
The American Canoe Association (ACA) says, “The keys to managing any risk are knowledge and skill.” (1) The former is the purpose of this paper; to caution and inform, not frighten. Keep in mind, venturing out on the water to have fun or exercise is optional. Returning home is mandatory.
Before giving in to the temptation of going for that long awaited first, or subsequent, Spring paddle this year on a beautiful warm sunny 70* F day, consider the following, even if you remember to think about the cold water and know about hypothermia.
* In northern latitudes during March, April and May the highest percentage of deaths occur from people going out on dangerously cold water. (2)
* Immersion in cold water kills more paddlers than any other hazard in the sport. (3)
* Cold water itself is the single most serious threat to the survival of a paddler; the colder the water, the more likely cold shock may take you. (4)
* Cold shock kills and occurs long before hypothermia can set in. (5)
* The most common fatal error for paddlers is wearing clothing inappropriate for the cold. (6)
DEFINITIONS
COLD WATER has a number of definitions. In Alaska and British Columbia some sources say it is water below 77* F (25* C) (7) (8) or it is water below 70* F (21* C) (9). Others report it is below 60* F (15* C) (1) (6) (10). USCG data shows about 3/4 of all canoe and kayak fatalities occurred in water < 65* F (18* C). (6) Still others call the temperature at which water can be considered cold is “variable”. (11) The important concept for paddlers to recognize is the colder the water, the higher the risks with inadvertent cold water immersion.
COLD SHOCK describes a series of rapid, linked, involuntary and detrimental physiological events in the inadequately protected human body characterized by immediate loss of breathing control, incapacitation and high risk of drowning or sudden death when suddenly immersed in cold water. Most of these immediate body responses are increasingly fatal as the water temperature decreases.
HYPOTHERMIA is a process where the body loses heat to the environment (water or air) faster than it can produce heat. This lowers the body’s core (brain, heart and lungs) temperature with accompanying decrease in bodily functions critical for survival in proportion to the extent of the lowered core temperature. Hypothermia takes time; the rate at which it occurs is proportional to the coldness of the water and the victim’s lack of insulation.
New thinking and research over the past decade has given birth to the concept of cold shock from sudden cold water immersion. This now explains why some experienced paddlers have been found dead in their overturned boats with their paddle still in their hands apparently without having made an attempt to wet exit or why observers of fatal cold water accidents have reported “He just tipped over and never resurfaced” or ”He was a good swimmer and so close to shore but it looked like he was just flailing around and then just went under.” And why, in the most blunt message, 9 elite Marines in March 1968, trained as water safety instructors but wearing only sweat suits paddling the Potomac River on water that was 36* F, after their war canoe capsized, none could swim 100 yards to shore. None survived. (12) This signals that a physically fit person, who is a good swimmer in warmer water, has no guarantee of survival from the adverse effects of cold water unless they have prepared to be immersed. (1)
It is now understood cold water kills by cold shock, drowning and advanced hypothermia. (13) Unless death occurs at any point, this occurs in three continuous phases: an initial cold shock response, a short term immersion and loss of performance phase and long term immersion with onset of hypothermia. (11) This writing addresses the first two since much has been written about hypothermia.
PHASE I: INITIAL COLD SHOCK RESPONSE (1 - 4 minutes)
First, the extremely unpleasant sensation of sudden cold water on skin triggers a cluster of breathing and heart responses; their severity depending on the extent and rate of skin cooling. This immediate neuromuscular reaction can cause a series of huge uncontrollable gasps for air called the INVOLUNTARY GASP REFLEX. If your head is underwater, you immediately drown. It also causes the INABILITY TO HOLD YOUR BREATH while under water from a preimmersion mean of 45 seconds to a mean of 9.5 seconds (one subject averaged less than a second) in 41* F water. (14) Imagine the implication for an unprepared kayaker trying to set up for a roll or wet exit!
However, if you manage to rapidly resurface, you may then have either your lungs full of cold water and can’t breath or you will immediately begin to HYPERVENTILATE, which usually follows the gasp reflex and is characterized by rapid and deep in/out breaths equal to 600-1000% greater than normal breathing (16). The triad of hyperventilation, involuntary gasping for air and LACK OF BREATHING CONTROL makes it easy to inhale water and drown. Also, as higher than normal blood levels of carbon dioxide are being quickly exhaled while gasping and hyperventilating, blood pH rises (respiratory alkalosis) which can cause cardiac arrhythmias, cramps from muscle tetanus, and cerebral vasoconstriction which starves the brain of oxygen resulting in disorientation, confusion and LOSS OF CONSCIOUSNESS.
Simultaneously, cold water on body skin causes constriction of capillaries under the skin. This INCREASES HEART RATE, CARDIAC OUTPUT AND BLOOD PRESSURE. These changes alone may be tolerated by a young healthy person but can be dangerous for older paddlers with hypertension or other underlying heart disease. Other sequellae challenging the immersed paddler for survival in cold water include pain, claustrophobia and disorientation which causes PANIC. This stimulates release of adrenaline in the body (“fight or flight” response) which, normally, is our way of automatically protecting ourselves from harm. Paradoxically here however, it adds dramatically to existing cardiac changes from capillary constriction. These conditions, along with a huge volume of cold water in the lungs cooling the heart with accompanying blood chemistry changes, can precipitate CARDIAC ARREST and sudden death.
PHASE II: SHORT TERM IMMERSION AND LOSS OF PERFORMANCE (1/2 hour)
If cold shock is survived but immersion continues, body cooling proceeds rapidly. Called "cold incapacitation", in minutes this leads to decreased extremity neuromuscular activity and blood flow causing finger stiffness, poor coordination of motor activity and considerable loss of strength. (16) The loss of motor control makes it difficult, or impossible, to perform survival procedures like rolling, reentry, blowing your whistle and signaling for help or grasping a rescue line. Along with disorientation and panic, it can easily account for the reports of apparent “flailing about” of good swimmers in their death throws of cold water immersion. In these critical minutes, amplified by not wearing a PFD, the cold water victim, by inhaling too much water or by inability to maintain survival skills of staying afloat, swimming or grasping a line, ultimately drowns (16).
PHASE III: LONG TERM IMMERSION WITH ONSET OF HYPOTHERMIA
The reader is referred to multiple other sources.
PREVENTION OF COLD SHOCK
1. Do not go out on cold water if capsize is likely; paddle only on warm water. This is not realistic for most.
2. Take the temperature of the water before venturing out on it. Know what you are dealing with.
3. Wear a PFD that will keep your nose, mouth and head out of the water or you can drown without immediate assistance from someone else. Many Class III and V PFD’s worn by paddlers will not right you if you cannot right yourself or are unconscious. (4) Without a PFD in cold water, you can drown without ever coming back to the surface. No second chances here.
4. Wear protective clothing. The critical areas are the torso, head and neck. Dress to balance clothing for water and surface conditions (7) but keep in mind it is the water temperature that deserves most attention for cold shock protection. The colder the water, the more you need protective clothing designed to keep the cold water off your skin which means seals at the neck, wrists, waist and ankles along with a neoprene head and neck hood. Judgment and common sense can help. If you are inexperienced, get advice from an experienced paddler.
Dry suits and neoprene wet suits are uncomfortable and often too warm, many claim, on a nice day but they will protect your torso from the immediate effects of cold water and decrease the chance of cold shock. One source states that without insulative protection underneath, a dry suit is not protection from cold shock. (3)
Polartec 2000, a new high tech tight fitting material with a fuzzy comfortable inner layer and windproof and near waterproof double outer stretchy layers, prevents the rapid movement of cold water to the skin. (15) It acts like a wetsuit and is rated to 2.5 mm neoprene. Different shapes for the corresponding body parts (feet, hands, head and neck, torso) are available. It has promise to decrease cold water mortalities since more boaters may wear it (it’s reportedly comfortable), it insulates and slows water ingress to skin.
ACA (American Canoe Association) Recommendation for Paddling in Cold Water (1)
* When the water temperature is < 60* F, wear “specialized insulating clothing”
* Always wear a wet suit or dry suit
If combined air/water temperature is < 120 * F
If you plan to paddle far from shore in cold water
In milder weather when you expect repeated exposures to cold water
Recommended Layers for Cold Water Paddling (if no full dry/wet suit) (4) (7) (14)
Neoprene head and neck hood (**) or
Fleece/wool neck warmer and skullcap (**)
Poly pro long johns (**)
Hydroskin farmer john (**)
Wind/rain/paddle pants
Neoprene booties (**)
Poly pro top (**)
Hydroskin top (**)
Fleece/wool top or sweater
Paddle jacket (best: dry with neck, wrist and waist seals)
Pogies or paddle gloves (**)
(**) Could be replaced by Polartec 2000
5. Never paddle alone on cold water.
6. Some recommend practicing voluntary cold water exposure (progressively colder showers before practice cold submersion) in order to build up your tolerance to cold water. (3) This, however, along with jumping in cold water to test your choice of protective clothing, is inherently dangerous.
CONCLUSION
The main objective in paddle sports is to stay safe. For the informed and responsible paddler on cold water, acceptance of the issues of cold shock means dressing appropriately, maintaining your skills and avoiding cold water immersion to keep from drowning in the short term and warding off hypothermia in the long term. Grandpa, an old Navy man, used to say, “Water (the sea) simply waits for the innocent but actually stalks the unprepared, the careless and the arrogant.”
ADDENDUM: ADDITIONAL COLD WATER AND ASSOCIATED INFORMATION
* Statistically, canoe or kayak capsize occurs equally on calm or rough water. (6)
* Cold water removes heat from the body 25 - 30 times faster than cold air - much from the head and neck. (1) (7) (8)
* Physical activity in cold water increases heat loss. (6)
* Alaska has 10 X the national boating fatality rate. (9)
* More than 50% of fatal boating accidents (PA) occur in cold water, often fair weather, close to shore. (6)
* The killing factor is often that first shock of cold water on the body. (8)
* Strong swimmers wearing a PFD have died before covering 100 yards in cold water. (14)
* In water < 40* F, a strong man can expire before swimming 100 feet. (14)
* An average person has a 50/50 chance of surviving a 50 yard swim in 50* F water. (13)
* A 50 year old person in 50* F water has a 50/50 chance of surviving 50 minutes. (13)
* An unclothed person in 34* F water will maintain core temperature for 20 - 30 minutes. (1)
* Of 130 drownings in Canada in 2004 (16)
- 60% drowned in water under 10* C (50* F)
- 34% drowned in water between 10* - 20* C (50* - 68* F)
- 48% were in a boat that capsized or was swamped
- 43% were less than 2 meters from shore/safety (shore, boat, dock, etc)
- 66% were less than 15 meters from shore/safety
- Only 12% were properly wearing a lifejacket
* Of 524 fatal boating accident drownings in the US in 2002 (17)
- Nearly 85% of the victims were not wearing a PFD meaning 440 lives could have been saved if boaters had worn a lifejacket
- Over 48% (254 of 524 total) drownings occurred in boats less than 16'
- Canoes/kayaks were the 2nd most common type of boat involved in drowning incidents (1st type was open motorboat)
* Of 710 boating related deaths in 2006, the USCG reports 9 out of 10 persons were not wearing a PFD (18)
* "Wear a Lifejacket" (19)
- People tend to drown in silence and without attracting attention.
- The struggle to breathe and stay afloat rarely enables them to wave their arms or call for help.
- 75% of boating fatalities could have been prevented if the victim were wearing a lifejacket.
* In Washington State, kayakers had the highest use (87%) of wearing a PFD, while motorboats had the lowest use (21%). (20)
* "In 2007, 107 fatalities were attributable to canoes, kayaks and rowboats. The use of properly fitted lifejackets could have prevented nearly all those fatalities." (21)
REFERENCES
(1) “Cold Water Survival”,
www.acanet.org/safety
(2) “Baby It’s Cold Outside (believe it or not)”, Pennsylvania Fish & Boat Commission, Apr 21, 2005,
www.sites.state.pa.us
(3)
www.atlantickayaktours.com/pages/expertcenter/cold water
(4) Sea Kayak Chesapeake Bay,
www.seakayak.ws
(5) “Cold - a Factor in Water Deaths”,
www.wainwrighth.army.mil/safety/winter
(6) “Critical Judgment II”, American Canoe Association, Understanding and Predicting Canoe and Kayak Fatalities 1996 - 2002, 2004.
(7) “Cold Water Immersion”, Alaska Sea Kayaking Symposium,
www.aksks.org
(8) Workers Compensation Board of BC, WS04-01,
www.worksafebc.com
(9) “Cold Injuries Guidelines”, Version 2003, State of Alaska,
www.chems.alaska.gov
(10)
www.americanboating.org/hypothermia
(11) “Immersion in Cold water and Hypothermia”, J Tsung, MD,
www.nykayak.com
(12) “Off Season Boating, Cold Shock and Hypothermia”,
www.enter.net/~skimmer/coldwater.html
(13) “Safety On (and in) the Water”,
www.capital.net/com/nckayak/nck_safety_p4.html
(14) “Hypothermia and Cold Shock”, P Siedel, USCG Aux,
www.auxguidanceskills.info/press/hypothermia.html
(15)
www.hendersonusa.com,
www.seattlefabrics.com
(16)
www.coldwaterbootcamp.com/pages/1_10_60v2.html
(17)
www.uscgboating.org/statistics/boating_ ... s_2002.pdf
(18)
www.cdc.gov/HomeandRecreationalSafety/W ... rinjuries- factsheet.htm
(19)
www.drowning-prevention.org/drowning_fact_sheet.pdf
(20)
www.drowning-prevention.org/pdf/obs_2000.pdf
(21)
www.commanderbob.com/canoes.html
Rev 03/06/09
