I should have said “ breathalize those that appear or smell to still be intoxicated from too much alcohol the night before”. Or maybe if they’re overheard bragging about getting wasted the night before and it raises some concerns. Rather than just kick someone off the boat or bench them for the trip, maybe a breath test might be more fair? Physical proof they are still too impaired to dive safely. Alcohol exacerbates narcosis.
I was on a multi day liveaboard on the Peace once and a guy had one small glass of wine with his dinner. The captain would not let him do the night dive after dinner, no matter how much arguing the answer was absolutely not! This went on for 15 minutes with the guy almost getting belligerent. It was awkward. They have a standing policy of no alcohol and diving period. You can have a beer but your diving is over for that day. I would also guess that if a group of divers decided to crack open a big bottle of Jack Daniels and get trashed one night, the captain could also make a judment call the next day if he want’s to let them go in the water.
So I have to ask what’s the difference, location only?