Titanic survival, ice cold water?

Question

When the RMS Titanic sank, there were not enough life boats, many hundreds of people went into the cold water and many died from hypothermia.

The water temperature in the area where Titanic sank, which was well below normal, ... The coldness of the water was a critical factor, often causing death within minutes for many of those in the water. Source

A few apparently survived for several hours in the water

A small number of passengers and crew were able to make their way to the two unlaunched collapsible boats, surviving for several hours (some still clinging to the overturned Collapsible B) Source

What made it possible for those few to survive hours in water reported to be 28 °F (−2 °C)?

If I know my ship is sinking and I may be in cold water for several hours, what choices (type of clothing?) can I make that increase my chances of survival?

Related: How dangerous is swimming fully dressed in cotton/denim clothes?

Answer 1

The US Coast Guard has done a number of studies too try and predict this and it looks like survival times can are highly dependent on the person and what they are wearing when all of the other factors are the same.

ST was reduced to 5.3 hours if the body fat level of the victim changed to “very lean,” and increased to 8.5 hours if the fat level changed to “very fat.” ST increased to 25.1 hours when the victim with medium body fat wore “Dry Suit, Double Pile, & Vest.” As noted above, clothing insulation increases ST significantly, thus, it is critical to pay attention to what clothing the victim might be wearing. ...

Individual differences in survival times are high. Even under similar conditions, some people survive only for a few hours, while other victims survive much longer. One factor affecting ST is body build, i.e., height, weight, and body fat percentage

...

Predicted STs demonstrated significant variance in the probability of survival. About 50% of the test population should survive hypothermia for 2.8, 5.0, 7.4, and 12.6 hours at water temperatures of 0°, 5°, 10°, and 15°C, respectively. At 0°C, ST varied from 1.2 to 3.8 hours. That range of predicted ST values appeared to be consistent with events during the Titanic shipwreck, where water temperature was near 0°C and virtually no survivors were present after 2 hours (29).

PROBABILITY OF SURVIVAL DECISION AID (PSDA)

From the same study, it also matters how much of the body is immersed with more immersion leading to shorter survival times.

Now, as one can't change their height, weight or body fat percentage at a moments notice, then all that leaves is getting more insulating clothes. In fact, there are drysuits designed specifically to keep a person from getting hypothermia.

An immersion suit, or survival suit (or more specifically an immersion survival suit) is a special type of waterproof dry suit that protects the wearer from hypothermia from immersion in cold water, after abandoning a sinking or capsized vessel, especially in the open ocean. They usually have built-on feet (boots), and a hood, and either built-on gloves or watertight wrist seals.

Source

If you don't have a immersion suit, do note that on page 20 of these recommendations for the Coast Guard, that any clothes are better than none and that only being partially immersed leads to much longer survival times.

Answer 2

Any amount of insulation helps.

There are 3 main areas of heat loss. Head, sides of chest, and groin area.

Any form of fabric will work. Yes, even cotton. (Cotton's problem is when it's in the air.)

As an exercise try this:

While wearing a life jacket in the water, remove your belt, then put it under your knees and around your neck so that your your knees are held close to your chest. Do this in a way that allows you to duck out of it without having to fumble with the buckle. Clamp your arms to your sides. This doesn't work well if you have short belt (small waist) compared to your height.

Float like this for several minutes.

Undo the belt and move. You will notice a rush of cold, as you dissipate the warm water near your body.

Note: I did this experiment using a horse collar type life jacket, not the more modern vest type. Initial experiments should start with just hugging your knees to your chest to see that you float stably in that position.

If you find your self on a Titanic replay, look for a garbage bag. Dress as warmly as you can, then bite holes in the two bottom corners and the middle of the bottom, and pull it over your head over the top of your life jacket.

The holes will stretch open, but will be snug. Use your belt to fasten the bottom edge of the bag close to you, or tuck into your pants. If you can, tie the corners between your legs. Ideally drop your pants, tie between your legs, and pull your pants up.

This slows the water exchange between your clothes and the sea. The water warms up some, and your survival time lengthens.

A woollen hat with a bread bag over it also helps.

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A garbage bag is a good piece of survival gear if you are in the mountains for the same reason. Test: On a winter day go outside with a bucket of water, dressed in a t-shirt. Get someone to pour the bucket over you. In a very short time you will be quite cold.

Put on your garbage bag. Instantly you feel warmer:

• You've blocked the evaporation that was taking place from your wet clothing.
• You've blocked the chimney effect of warm air next to your body rising away.
• You've blocked the breeze.

Now this is not a panacea: A dry parka is certainly a better bet. But you can put a spare garbage bag in the bottom of every daypack you own.