Cold Water Shock
Recent research identified the fact that many people don't wear their lifejackets because they think that falling in the water is an occurrence that they could relatively easily get through because they believe themselves to be strong swimmers, or that their crew will rapidly get them from the water.
However established science renders those beliefs questionable.
COLD WATER SHOCK is a leading cause of death that many people fail to appreciate. Many deaths recorded by coroners are mistakenly attributed to either hypothermia, or drowning, when in fact the cause of death, or cause leading up to the death, is something different. One of the authors of the seminal work "Essentials of Sea Survival", Professor Mike Tipton, is quoted as saying "if you are lucky enough to survive long enough to die of hypothermia, you have done very well; most die in the first minute of immersion". It is cold water shock that tends to kill people around our shores.
What is cold water shock?
It is the body's short term involuntary response to being suddenly immersed in cold water. The waters around the UK are officially cold (10 - 15°) and when the body enters this cold environment there are a number of physiological responses. The sudden lowering of skin temperature is one of the most profound stimuli that the body can encounter. The responses tend to be short lived, but threaten survival.
The responses are...
First of all, closure of the blood vessels in the skin which results in increased resistance to blood flow. The heart then has to work harder and blood pressure increases. At the same time there is a "gasp" response which can result in water being breathed rather than air. Concurrently the breathing rate changes dramatically, it can increase by as much as tenfold. All these responses contribute to a feeling of panic, and are more difficult to manage if no lifejacket is worn and the casualty is struggling to stay afloat. After a while the body gains control of itself and much of the excessive reaction reduces. However coping with cold water shock certainly takes its toll in terms of long-term survivability. Unsurprisingly one effect of cold water shock is to induce a heart attack, even in the relatively healthy and relatively young - hence the possibility of wrong inquest verdicts because it is water in the lungs that is thought to be the cause of death (or sometimes even hypothermia) when it is in fact heart failure that has caused the water to enter the lungs. Wearing a lifejacket allows you to weather the Cold Water Shock and prolong your survival long enough for you to be recovered, either by your own boat or by the rescue services.