The Coast Guard's annual report “Recreational Boating Statistics” shows that a boat operator or passenger with a blood-alcohol concentration above the legal limit runs a significantly increased risk of being involved in a boating accident.
This is why:
1. Sun, wind, noise, vibration and motion – “stressors” common to the boating environment – intensify the effects of alcohol, drugs and some medications by causing fatigue, which in turn impairs a boater's balance, coordination and reaction time.
2. As blood-alcohol concentration goes up, the ability to process information, assess dangerous situations and exercise sound judgment becomes increasingly difficult. Peripheral vision, depth perception, night vision, focus and the ability to distinguish colors (particularly red and green) are reduced.
3. Finally, alcohol reduces inhibitions and brings on a false sensation of physical warmth, which could cause a person to enter and/or remain in cold water until hypothermia sets in. With these impairments, accidents are more likely and more deadly for both passengers and boat operators. Alcohol is a factor in nearly one in five recreational boating fatalities; U.S. Coast Guard data show that in more than half of these cases the victims capsized their boats or simply fell overboard.