Easterly has the right idea. Social drinking in a marina is wonderful. I only had one bad experience when a guest had a snootful and took exception to a black sailor coming aboard my boat. People can completely change with a few drinks in them. But that was a once in a life time exception to a series of warm and welcoming evenings.
Now the other side of the coin. Drinking at sea is not to be winked at. Cruising is a team sport and the safety of everyone is dependent on the capabilities of each. So, as a rule, no alchohol consumption when under way. No illegal substances aboard at any time. Sorry to be a wet blanket. That's just the way it is on my boat.
Isn't it amazing how common sense seems to prevail when the penalty for being even a little tipsy could VERY likely be costly or tragic. This reflects the challenge involved in operating a boat and is what makes it such a great thing to do. You know you need to be firing on all cylinders all the time. Even the prospect of trying to set sail the next day with a hangover is enough to dissuade me from popping too many.
We make our own alcohol on board.
Sugar and water plus yeast, leave it a week and run it through a reflux still. (our alternative water maker?)
Then run it through activated charcoal 3 times and no hangover (honest) your legs won't work, but you won't have a hangover.
We mix our with orange juice or coconut juice, plenty of ice, never before 3 pm and not while underway.
Cost $1.00 a 1 liter bottle.
Works for me.