Drinking and Diving: How Much Alcohol Is Too Much?

You’re having so much fun on your dive trip that after cocktails, you decide to have more wine with dinner, and a brandy as a nightcap. Should you really go on the first morning dive? It’s one thing to have wine with dinner, it’s another to drink until 2 a.m., then wake four hours later for the early-morning dive. And if you’re the sober dive buddy, what is your responsibility?

Divers Alert Network (DAN) states that alcohol will impair your physical performance, concentration and judgment underwater, plus mask symptoms of decompression sickness for many hours until your blood alcohol concentration (BAC) level reaches 0.0 percent. (The American Medical Association recommends the upper BAC limit for driving as 0.05 percent.) So the more partying you do, the higher your BAC goes, and the higher your risk for injury as a hungover diver.

Look at it another way: DAN estimates that alcohol metabolizes at an average of 0.3 ounces of pure alcohol per hour. So say you drink a 12-ounce can of Miller Lite. It contains 0.384 ounces of pure alcohol, so you’ll metabolize it in approximately 80 minutes. A domestic draft beer has 0.48 ounces, so it’ll take around 90 minutes. Drink four of those and it’ll take six hours for a respectable BAC. That’s okay if you stop before midnight, not so much if you’re drinking into the a.m. hours - - and if you drink more than that.

There’s scant research about alcohol’s impact on diving, but DAN won’t consider doing more, says senior research director Petar DeNoble. “First, excessive drinking is related to many health problems already, so conducting a separate study would make it look like DAN is trying to provide excuses for drinking and diving. Second, the effects of drinking on physiological functions are difficult to measure, especially because most effects may be dose dependent.”

Dive operators vary on their view of handling heavydrinking divers. We asked a few liveaboards for their take, and it ranged from crackdown to laissez-faire. Mike Ball Dive Expeditions in Australia is one of the strictest. Its procedures manual recommends lights-out at 11 p.m., requires parties to end at midnight and has a four-drink maximum over 24 hours. “Guests who wish to drink beyond that are advised they’ll need to skip the early-morning dive,” says operations manager Craig Stephen. Crew records the names and time of late-night drinkers in their log, and if those divers insist on doing the first dive, they must sign a “diver refusing advice” waiver.

On the other end is the Peter Hughes fleet, saying the “fit to dive” decision is entirely up to its guests. “We treat divers as responsible adults, capable of governing their own actions and diving within their limits,” says vice president Larry Speaker. “Our crews don’t have the expertise to diagnose or judge the ‘quality’ of each person’s decisions. But during our initial safety briefings, we do discuss responsible diving.”

The Aggressor Fleet is somewhere in between, with no written standards about heavy drinking, but president Wayne Hasson says, “Our on-board policy includes suspending diving for anyone who is in question of being a danger to themselves or another diver.” He says dive buddies should play a role in keeping hungover divers on deck. “They should inform the divemaster in such a case, but they should also advise the diver not to dive under those conditions.” Drinking and Diving: How Much Alcohol Is Too Much?