Howdy All:
Good discussion. I think that we would all agree that it is not wise to dive when significantly impaired. Obviously, diving with alcohol in your system would impair a diver, but so would the after effects of overindulgence.
I've covered the diuretic properties of caffeine elsewhere (see:
http://www.scubaboard.com/showthread.php?s=&threadid=12197 ), but let's talk about alcohol for a minute. The alcohol content of different drinks varies
widely, so for simplicity's sake I'll stick with the USDA's definition of a "standard serving" of alcohol of 14 grams. That would be roughly 360ml (12 oz.) of US beer, 150-180ml (5-6 oz.) of wine, or 45ml (1½ oz.) of spirits.
Alcohol is indeed a diuretic. You will excrete about an extra 10ml of urine for each gram of alcohol you consume (10ml/g). In order to become "dehydrated" you must lose more water than you take in. Do the math on the above drinks. If you drink a 360ml beer, you will urinate 140ml due to the alcohol- for a net
gain of 220ml of fluid. If you drink a 150ml of wine, you will urinate 140ml of that due to the alcohol- for a net gain of 10ml. If you drink a 45ml shot of tequila without any chaser, you will lose 140ml due to the alcohol for a net loss of 95ml, but if you drink 45ml of rum in a 360ml rum and Coke (with caffeine free Coke ;-) you are back to a net gain of 220ml of fluid.
So (like coffee) no alcoholic drinks will hydrate you
as well as drinks without any diuretic effect, but only some
dehydrate you. If you continue to drink non-diuretic drinks in the volumes you normally would on a dive trip in addition to any moderate use of alcohol, you are unlikely to become dehydrated. The idea to drink a couple of glasses of water for each alcoholic drink is maybe just a tad overboard, but it's hard for a healthy diver to drink too much water so it's basically good advice.
HTH,
Bill
. never close to when i dive.
