For everyones' information, the water temperature that night was 28 degrees Fahrenheit.

They know this because the bridge watch has someone take the temperature every two hours and has it recorded into the ship's log.

Just to clear the matter, it usually takes longer than 3-4 minutes to die in that cold of water from hypothermia. Hypothermia in that temperature takes a little longer (anywhere from 30 minutes to an hour, but not much more).

But another reason that some people may have died sooner is not from hypothermia, but actual suffication. When people are in an environment as cold as that water, they tend not to take normal deep breaths.

Sometimes, if a person gets so cold that they takes shallow breaths, they are not getting enough oxygen and therefore they pass out and die.