1-10-1 rule
Also: 1-10-1 principle
The 1-10-1 rule sums up what happens in cold water: 1 minute of cold shock, about 10 minutes of meaningful movement, about 1 hour until unconsciousness from hypothermia.
The rule comes from cold-water research (Cold Water Boot Camp) and is a memory aid, not an exact time. Wikipedia describes the same phases: cold shock in the first 2 to 3 minutes, then muscles and nerves cool down (swim failure), and after about 30 minutes hypothermia sets in. Shortly before, during or after rescue, circulatory collapse can occur.
- 1 minute: control your breathing, don't panic.
- 10 minutes: use the time to rescue yourself: into the boat, to the bank, secure your PFD.
- 1 hour: with a PFD there's time for rescue; without one you drown before that.
The times depend heavily on water temperature, clothing and body build. Wikipedia states that 10 °C water can kill an adult in about an hour, ice-cold water in 15 minutes.
Sources and further reading
Research as of 13 Nov 2026. We have marked manufacturer information as such.