Many divers think it is fine to drink alcohol before, during, and after dives. This is simply not true. Alcohol has many effects on the body, none of which are conducive to diving safely. If you dive while under the influence of alcohol you will not only be putting your own life in danger, but that of your dive buddy too. Do really want that much responsibility on your shoulders? Of course not, so let's take a closer look at why diving and alcohol don't mix.
Alcohol is a depressant. It makes you feel as though you can do more and accomplish more, but it actually has the opposite effect. If you have had alcohol within 24 hours of a dive, then the following behaviors will be negatively affected:
- Concentration and attention span
- Reaction time
- Perception
- Ability to process information
- Ability to multitask
- Visual tracking performance
- Fine motor skills and psychomotor tasks
Even if an individual does not feel or appear impaired, the impairment is present and will affect the diver's ability to function properly during the dive. In fact, it has been proven that these behaviors will be negatively affected for many hours after the blood alcohol level has reached zero.
So aside from the effects on behavior and ability to perform underwater, does alcohol affect diving in any other way? The answer is a resounding yes because the consumption of alcohol too soon before a dive can increase the diver's risk of getting decompression sickness. This is because alcohol acts as a diuretic, which means that it dehydrates the body. It does this by inhibiting the kidneys from retaining water and consequently the blood volume is reduced. This will, in turn, make it more difficult for the gas bubbles to be eliminated on ascent and this means that decompression illness is far more likely to happen.
Alcohol has another effect on the body that has a large amount of significance when it comes to diving. Most often, when divers are in the water they are at high risk of losing heat from their bodies. They wear the appropriate suit for the temperature in which they are diving, but heat loss still occurs. This is because water is a medium that pulls heat from our bodies 25 times faster than air does. What does this have to do with alcohol? Well, there is a common misconception that alcohol warms our bodies. However, while it can actually help us feel warmer, this is actually what happens. Alcohol is considered a peripheral vasodilator, which means that it helps the blood vessels near the surface of the skin expand, which allows more blood to flow through them. While this does indeed feel warming, what is happening is that this extra blood at the surface is being taken from the core, which means that core heat is being lost. Alcohol also suppresses the shiver response of the body. All of this means that a diver who has been drinking alcohol prior to a dive is at greater risk of getting hypothermia and drinking after a dive will make it take longer for a diver to warm up.
In addition to the above, the increased peripheral circulation that alcohol causes, might also contribute to an increased risk of decompression illness because it might increase the nitrogen absorption by the blood. Alcohol also causes the blood vessels in the muscles to constrict and this raises blood pressure, which in turn can place a significant stress on the heart, which is already under stress from the physical strain of diving. Couple this with the fact that alcohol actually saps one's energy and you are left with an enormous amount of physical activity for someone to perform. If you were on dry land you could easily bow out and take a rest, but when you are underwater you don't have that option and it is believed that alcohol consumption might be a contributing factor in the number of dive accidents that are related to heart disease. Finally, drinking might cause vomiting to occur, which can cause asphyxiation during a dive.
There most certainly is a time and place for social alcohol consumption, but any diver worth their regulator should know that that time is not before the diving fun begins or even immediately after. If you are on a diving trip, save your drinking until the end of the trip after all the diving is done, a time when you can celebrate a few days of wonderful diving and the friends new and old that you were able to dive with during that time. Then you know that you will be diving as safely as possible and you can simply relax and enjoy your favorite sport.