Did you know that drinking while driving a boat is worse than drinking and driving a car? According the U.S. Coast Guard, "alchohol is more hazardous on water than on land." Whether or not you are the driver of the boat, boating under the influence is a bad idea.
Drinking and Boating Don't Mix

Photo courtesy U.S. Coast GuardI have seen this first hand as a former U.S. Coast Guard Coxswain and boarding team member during boating while intoxicated (BWI) boardings. The effects of being on a boat, including continual motion and vibration, sun, and engine noise, all collaborate to increase impairment more so than when a person is on land. The result is a sharply increased chance of boating accidents for both drivers and passengers.
The Coast Guard estimates that in over half the boating deaths involving alcohol, the victims fell overboard or capsized their boat. An intoxicated person in the water faces a double danger - being unaware of the onset of hypothermia and increased disorientation resulting from inner ear disturbances.
Boating While Intoxicated is Illegal

Photo courtesy U.S. Coast GuardAs with drinking and driving, boating while intoxicated is illegal. Both the Coast Guard and individual states enforce BWI laws, and violators face substantial fines, losing their operator privileges, and jail time. The Coast Guard and state law enforcement agencies have concurrent jurisdiction,meaning they can both enforce BWI laws. If the Coast Guard determines a person is boating while intoxicated, they will terminate the voyage and escort the boat to the nearest mooring. They can arrest the person, detain them until they sober up, or turn them over to state or local authorities. In my experience, most boaters determined to be under the influence were turned over to state or local authorities.
Don't Drink and Boat - Period
It's always best to plan to boat without alcohol. If you do drink, though, don't get in the boat while intoxicated - either behind the helm or as a passenger - always wait an hour per drink before operating the boat.