25 Apr Understanding Cold Water Immersion: Why Minutes Matter
Cold Water Kills Quickly: A Real-Life Reminder from Our Local Waters
Last winter, a local boater set out for an afternoon sail around Sidney, BC. He had not checked the marine weather forecast, and while at sea, rapidly developing winds caused his vessel to capsize. Wearing a PFD and carrying a portable VHF radio in his jacket, he was able to send out a distress call—an action that ultimately saved his life.
Our marine search and rescue crew was dispatched and arrived about 30 minutes later. We found the man clinging to his overturned boat, unable to pull himself aboard. The cold water had quickly robbed him of strength and coordination. He was already showing signs of hypothermia and was in no condition to assist in his own rescue.
We’ve seen this before—people who lasted only a couple of hours in “summer” waters at 9°C, slipping into severe hypothermia. Others have succumbed much faster, dying within minutes from the shock of cold water immersion.
I recently had a young man in one of my classes who had been a competitive swimmer. He shared a story about attempting to swim out to a buoy about 40 meters from shore in an early spring lake. Halfway there, his extremities went numb and he barely made it back. He was shocked at how fast the cold water shut down his ability to swim. This is the silent threat of cold water: it doesn’t give you time to adapt.
In the Pacific Northwest—including all around Vancouver, the Gulf Islands, and Vancouver Island—the water is always colder than it looks. Whether you’re a paddler, sailor, kayaker, or just a casual boater, it’s critical to understand how fast cold water can claim a life.
When someone unexpectedly enters cold water, the body reacts in three critical phases—explained in the 1-10-1 Rule, widely taught in cold water survival training:
- 1 minute to get your breathing under control. The initial cold shock causes gasping and hyperventilation, which can be deadly if your head is underwater. It can also trigger cardiac arrest in vulnerable individuals.
- 10 minutes of meaningful movement before cold incapacitation sets in. The body shunts blood away from the limbs to preserve core temperature, quickly weakening your ability to swim or use your hands. This is your small window for self-rescue or activating your emergency gear.
- 1 hour of consciousness before hypothermia begins to set in. As your core temperature drops below 35°C, brain and body function decline. Unconsciousness typically occurs when core temperature reaches 28–30°C. Without rescue and rewarming, cardiac arrest and death follow soon after—especially if you’re not wearing a lifejacket.
Even strong swimmers cannot outlast the effects of cold water. The right gear and preparation are your best defense. Always wear your lifejacket, carry a waterproof means of communication like a VHF radio or PLB, and check the weather and sea temperature before heading out.
Where Do People Drown? Know the Risks
According to data from the Lifesaving Society of Canada, about 70% of drownings in Canada happen in open water such as lakes, rivers, and coastal waters—including areas all across BC. Many of those who drown never intended to be in the water at all.
Additional stats worth noting:
- Nearly 80% of drowning victims are male.
- More than half were not wearing a lifejacket.
- Cold water is a factor in over 60% of boating-related fatalities in Canadian waters.
- Most drownings occur within 15 metres of safety—yet the shock and loss of motor control can make that short distance impossible to cover.
These aren’t just numbers. They reflect real lives lost—many of which could have been saved with better awareness, training, and gear.
Cold water doesn’t care how experienced you are. Preparedness is your only defense.
For more information, read “Survival in Cold Waters” (2003), Transport Canada.
About FMI Marine
FMI Marine provides Transport Canada recognized VHF, SVOP, and SDV-BS training. View our schedule of marine safety courses. Courses are taught in our North Saanich, BC classroom and we travel Western Canada providing training to organizations and groups. If you’d like FMI to provide training at your location, please contact us.