Most people get confused by the two different phenomenon that will kill you when falling in cold water:
- the thing people have in mind is hypothermia (or more accurately, if you don't have a life jacket drowning because your body can't stay afloat because hypothermia paralyzes your muscles), but as your link point out, it's a pretty slow process: it will depend on water temperature and body composition (the slimmer the worse) but it will still always take at least 15-20 minutes in the least favorable case.
- the second factor, which is much faster to kill, is Cold shock response: basically if you fall into cold water, you're very likely to have incontrollable breathing while underwater, and will drown near instantly. That's why more than half the people falling in cold water will be dead in less than a minute. But if you survived this first phase (very likely if you have a life jacket) then you'll be fine for tens of minutes afterwards.
Always wear a life jacket when on a boat even if you're an Olympic swimmer.
- the thing people have in mind is hypothermia (or more accurately, if you don't have a life jacket drowning because your body can't stay afloat because hypothermia paralyzes your muscles), but as your link point out, it's a pretty slow process: it will depend on water temperature and body composition (the slimmer the worse) but it will still always take at least 15-20 minutes in the least favorable case.
- the second factor, which is much faster to kill, is Cold shock response: basically if you fall into cold water, you're very likely to have incontrollable breathing while underwater, and will drown near instantly. That's why more than half the people falling in cold water will be dead in less than a minute. But if you survived this first phase (very likely if you have a life jacket) then you'll be fine for tens of minutes afterwards.
Always wear a life jacket when on a boat even if you're an Olympic swimmer.