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Hypothermia.

With winter rapidly approaching it is time to start thinking about the dangers associated with hypothermia.

 

So What is hypothermia exactly? 

Hypothermia is the condition of having an abnormally low body temperature.  Boating during winter may pose a very real risk of someone on board becoming hypothermic by merely being exposed to the elements without adequate protection which may be as simple as clothing.  Obviously immersion in cold water is the greatest risk to a boater but exposure to temperatures between 0 and 10 °C may result in hypothermia. 

Hypothermia occurs when a persons core body temperature drops below 35 °C as opposed to our normal body temperature of 37 °C. 

There are various stages of hypothermia and your ability to recognise them and act accordingly just may be the difference between and safe or tragic day on the water. 

1 - Uncontrollable shivering.  How many of us have been in this position and actually realised that we were on the way to becoming hypothermic? 

2 - Lack of shivering.  As mild hypothermia turns into severe hypothermia, the body will actually stop shivering.  As the core body temperature drops below 32 °C there is a risk that the person will lose consciousness. 

3 - As the core body temperature continues to drop to about 30 °C, the hypothalamus fails to function and the body can no longer regulate it's own temperature.  Breathing and heart beat slows down significantly becoming almost undetectable.  As a result, the body is starved of oxygen with fatal consequences if not treated promptly. 

Hypothermia symptoms at various stages may include - feeling cold, pale skin, shivering uncontrollably, loss of concentration, loss of fine motor skills e.g. difficulty threading a fishing line or tying a knot, feeling lethargic or tired, confusion and irritability, feeling dizzy, having difficulty breathing, loss of gross motor skills, lack of shivering, difficulty talking, slow breathing, dilated pupils, unconsciousness, death.

 

How long can you survive in cold water? 

Here is a bit of an idea as to how long a person can survive in cold water.  Various factors such as weather e.g. wind, the amount and type of clothing worn and body position whilst in the water, physical fitness and/or attributes can have an effect on these times. 

 

TEMPERATURE  (°C)               EXPECTED TIME BEFORE EXHAUSTION             EXPECTED SURVIVAL TIME

                                                      OR UNCONSCIOUSNESS                                                

 

           0                                                < 15 MINUTES                                               45 MINUTES

         0-4                                              15-30 MINUTES                                            30-90 MINUTES

        4-10                                              30-60 MINUTES                                               1-3 HOURS

       10-16                                                1-2 HOURS                                                  1-6 HOURS

       16-21                                                2-7 HOURS                                                  2-40 HOURS

       12-27                                               3-12 HOURS                                            3HRS - INDEFINITE

        >27                                                 INDEFINITE                                                  INDEFINITE

 

 

But does our water get that cold?  

My word it does, particularly in the Alpine areas.  I have seen the water temperature at Sue City - Talbingo Reservoir as low as 4 degrees when water was being released straight off the mountains into the reservoir.  You can only imagine how much colder the water temperature gets as you keep travelling up the hill to places like 3 Mile Dam, Tantangara, Eucumbene and Jindabyne.  Don't discount how cold water being released from dams such as the Hume Weir is either, even in summer.  Remember that the water is being released from the bottom of the pond, not the top which is relatively warm and it is COLD!

Wearing a lifejacket is not going to stop you from getting hypothermia.  In reality all it is going to do is help keep your head out of the water for longer and help the rescue agencies locate you should the worst happen.  If you are wearing waders to keep your tootsies warm when getting in and out of the boat, you are effectively placing a bloody big anchor around your feet.  It is compulsory to wear a lifejacket if you are wearing waders in a vessel.  Personally I wouldn't wear anything less than a PFD type 1 with at least 150N.  To buy jackets with a rating over 150N will be expensive but - what price do you put on a life? 

Should you be in a position where you know that you are going to end up in the water, wear as many layers of clothes as possible and of course wear your lifejacket.  If it is an inflatable lifejacket, don't forget to inflate it.  It is quite common in the stress and confusion of entering the water that a person totally forgets to pull the rip cord.  At all costs protect three areas of your body from heat loss - these are your head, armpits and groin.  Adopt the Heat Escape Lessening Position (HELP) which entails crossing your arms in front of you, crossing your legs and if possible wearing a hat or beanie.  The multiple layers of clothes will also assist in trapping some of your body heat.

If you have the benefit of being in the water with another person or people, huddle together, link arms and legs.  It is amazing how everyone's body temperature will slightly increase the temperature of the water trapped in the middle of the huddle.  It will buy you extra time as well as keeping together and offering support to each other.

Upon entering the water, be very mindful of trying to keep your face up.  The cold water will take your breath away and your first reaction is to suck in a deep breath and breathe erratically.  This reaction has unfortunately been the cause of numerous drownings when the person has sucked in a lung full of water and not air.  Something like 20% of victims die within 2 minutes of entering the water due to cold water shock.  About 50% of people die within 15-30 minutes due to cold incapacitation where you become unable to control your fine and gross motor functions and lose the ability to grip on to objects and even swim.

I would strongly recommend NOT boating alone in remote areas, at any time, let alone during winter.  You can see from the estimates of survival time above that despite your best efforts, you may not have very long if you are fully immersed in the water.  Even if the alarm is raised, there may be a significant time delay in any attempt at a rescue simply because of travel time to get to you.

If possible, remain with your vessel and climb on top of it or back in it - try to get out of the cold water.  This will also help rescuers to locate you if you are with the boat.

 

Treating Hypothermia.

If you are treating someone with hypothermia, remember that they will more than likely have lost feeling in their limbs.  First of all, remove them from the cold environment if and where possible.  Do not put them on top of a fire or heater to alleviate the risk of them burning themselves.  Do not give them alcohol - their body is already functioning slowly and alcohol being a depressant will only exacerbate their issues.  Wrap them in dry clothing or blankets and give them a nice big cuddle.  If there isn't anything dry available, leave the wet clothing on them to aid in trapping any body heat - it is better than nothing.  Seek medical assistance if and where possible immediately.  Placing a heat pack or hot water bottle under the arm pits and in the groin area will also help if available. 

I sincerely hope you never have to worry about hypothermia but reality is that we will more than likely lose someone this winter to hypothermia, drowning or a combination of both in the Alpine Lake areas.  Please do everything in your power to ensure you return from a day on the water safe and sound.

  

NB – the preceding information should be based as a general guide only.  

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