BOATsmart! Canada
Knowledge Base

Module 07 - Emergency Preparedness

Cold Shock

Cold shock occurs when a person is unexpectedly immersed into water that is 15°C or below and results in more fatalities than hypothermia as it can instantly cause:

Muscle spasms,
A rise in heart rate; and
Increased blood pressure

Additionally, cold shock will cause a person to instantly gasp for breath, and involuntarily inhale water, which can easily result in drowning. Plus, the sudden rise in heart rate and blood pressure can cause a heart attack or stroke.

Cold water can paralyze your muscles instantly, making it extremely difficult to put on a life jacket or PFD in the water. This is why you should wear your life jacket at all times! It won’t work if it’s still sitting on your boat when you fall in the water.

Remember: Cold shock can occur throughout the year, even during warm summer months when water temperatures can remain lower than outside air temperatures.

1-10-1

1-10-1 is an easy way to remember the phases of cold water immersion, and the approximate time that each phase lasts.

1- Cold shock: A sudden deep gasp for breath, followed by hyperventilation and a rise in heart rate. Cold shock will last for about one minute. During this time, it’s important to remember not to panic. Try to focus on getting control of your breathing. Wearing a lifejacket during this phase is critical to ensure you can stay afloat!

10 - Cold incapacitation: For approximately the next ten minutes, you will begin to lose the use of your fingers, arms and legs, and will likely lose your ability to swim. If you are in the water without a lifejacket, you will likely drown.

1- Hypothermia: Even in ice water, it can take up to one hour before hypothermia can set in, and you become unconscious. To increase your chances of survival during this phase, it’s important to understand the methods for how to delay hypothermia, self-rescue techniques, and how to signal your need for help.