Cold water immersion

Emergencies · Power & sail

Falling into cold water can kill within minutes through gasping and loss of muscle control, long before hypothermia sets in. Wear a life jacket, dress for the water temperature, and know what to expect and what to do in the first minutes.

What happens in cold water

• Cold shock: an involuntary gasp followed by rapid, uncontrolled breathing. If your face is under water at that moment, you breathe water in. The National Center for Cold Water Safety (NCCWS) says it can kill within seconds to a couple of minutes.
• Cold incapacitation: over the following minutes your fingers, arms and legs stop working and swimming fails. Without a life jacket, drowning usually follows.
• Hypothermia (a core temperature below 95°F [35°C]) comes later. It is usually not what kills people in the first minutes.

The 1-10-1 principle and its critics

• Physiologist Dr. Gordon Giesbrecht coined '1-10-1' (Cold Water Boot Camp): about 1 minute to get breathing under control after cold shock, roughly 10 minutes of meaningful movement, and about 1 hour before unconsciousness from hypothermia, even in ice water.
• The NCCWS calls 1-10-1 a myth. It says breathing can't simply be controlled, strength declines steadily from the first minute instead of lasting a set 10, and the phrase gives false confidence. It cites Giesbrecht's own writing that incapacitation takes 2 to 30 minutes.
• Both treat the first minutes as the most dangerous. Giesbrecht's program stresses wearing a life jacket; the NCCWS agrees a life jacket keeps you afloat but says only thermal protection such as a wetsuit or drysuit guards against cold shock and incapacitation.

How cold is cold?

• The NCCWS says to treat any water below 70°F (21°C) with caution and to consider thermal protection below that. It puts the most intense cold shock at 50 to 60°F (10 to 15.5°C).
• The RYA warns of a cold water shock risk in water of 15°C (59°F) or less. Check the water temperature, not just the air temperature, before you go.

If you go in

• Through the gasp, focus on keeping your airway clear and slowing your breathing; avoid panic.
• Use the first minutes, while your hands still work, to get back aboard or onto anything that floats.
• Don't swim for help; swimming fails quickly in cold water. Stay with the boat or something that floats.
• Slow heat loss: keep clothes on and buttoned, and use the HELP position (knees drawn to chest, arms crossed) alone, or huddle with others with children in the middle.

Life jackets

• In 2024, where the cause was known, 76% of people who died in U.S. recreational boating incidents drowned, and 87% of drowning victims with known life jacket use were not wearing one.
• A life jacket only helps if it is on. Put it on before you could need it: in cold water you won't have the time or the hands to do it.

Sources disagree on Timings in the 1-10-1 principle, Water temperature at which cold shock becomes a risk — left out rather than guessed. Check your local authority.

General guidance for recreational boaters, researched from the sources listed and written in our own words. Your equipment manuals, local knowledge, the Navigation Rules and a qualified instructor come first.