Can I bring alcohol on board?
Usually yes in moderation, and it is the captain's call. Some trips include beer, others are happy for you to bring your own, and offshore fishing days are not the place for heavy drinking.
Plenty of captains here are relaxed about a cooler of beer, and sunset and sailing trips often include drinks outright. Ask first — it is their boat and their call.
No glass on deck, and a captain can end a trip early if a group's drinking makes the boat unsafe. That is a safety decision and it is not refundable.