The best advice is let someone who is sober operate the boat. For your safety and the safety of others, you may wish to designate a sober operator. However, even passengers increase their risk of accident if they drink alcohol. The idea of designating a sober operator has its roots in automobile safety, where the possibility of drowning is not a factor, and may impart a false sense of safety if applied to boating. Persons drinking alcohol on a vessel and falling overboard face the further danger of hypothermia, a condition in which the body loses heat faster than it can produce it, causing a dangerous lowering of body temperature.
Death can result if the body temperature drops too low.
Alcohol greatly increases the effects of hypothermia, including disorientation, hyperventilation and involuntary taking of water into the lungs, heart attack, and numbness and the resulting loss of the ability to self-rescue. Boating and Waterways recommends that neither boat operators nor passengers drink alcoholic beverages while boating.