There is actually a way to get a little warmth when immersed in cold water. Loosely termed the huddle technique, it consists of a number of people staying together in a huddle - forming a very close ring. One at a time, a member of the 'ring' gets into the middle and the rest huddle close to that person. In that way, body heat is shared.
Unfortunately a wet body looses heat quicker than a dry one.
The worse thing you can do is to swim about - it uses up precious energy and you will tire very quickly.
The typical change in core or deep body temperature for an average individual fully clothed and immersed in salt water at a temperature of 50F (10C) is as follows:
Body temp at start.. 98.4F.. body enters cold water - shock causes panic and incapacitation.
during first hour, the pulse rate quietens but the shivering starts.
At one hour, the core temperature is down a degree. You now feel very cold and shiver like heck. Your hands become useless.
After 2 hours, your body temperature falls to about 94F. If there's no sign of help, you start to loose interest. You have problems with your breathing.
Between 2 and 4 hours, you are in danger of death from drowning - you get amnesia, your heart beat becomes irregular, your arms and legs get stiff and you may lose consciousness.
The danger point - the point where the chance of revival is very slim comes just after 3.5 hours for an average person. Hypothermia will set in rapidly, resulting in death.
The foregoing is from human physiology notes I took during survival training - what we termed 'water sports'. Actually Joughin did exactly what modern knowledge predicts. In fact, he had an even better chance. One of the most important things effecting survival under such conditions is the will to live. Joughlin had the comfort of knowing others were nearby therefore he always had a chance to survive. What the facts point to is a higher sea temperature.
Much has been placed on the evidence of the sea temperature found at the time. Sea temperature was taken at regular intervals for weather forecasting purposes- not to indicate the presence of ice. The method of taking it was to lower a canvas bucket into the sea forward of all over board discharges and just fill it with surface water. it was then hoisted quickly on deck. The thermometer was then placed in the water and stirred round while being read. The big mistake made by many mariners was to lift the thermometer out of the bucket to read it thus getting the air rather than the sea temperature.
Historically, the surface temperature in the area during January averages about 40 to 50 F. In April it can get as high as 60F. Any freezing water was probably from nearby ice and would only be a few inches on the surface. The freezing temperature was that of the air - not the water.
What is indisputable is that at a sea temperature of 32F, a human being wearing ordinary clothing will not be alive after an hour.
I suggest that the survival time of Jouglin is a good indication as to what the sea temperature just below the surface really was!