The "Pour out" is the cracking of the "Docking bottle" a bit earlier than it should have been opened: the bottle of duty-free spirits a seaman had purchased under bond (tax-free) to take ashore, but had decided to drink with his shipmates the night before the crew paid off in the home port. I remember many fond farewells to shipmates after a pour-out, but not so fondly the next day hangovers, while travelling home.