The captain’s bed is about the details. A captain’s bed would often have a raised lip along the front edge although would never built as a bunk bed. Twin captains bed with storage includes drawers at the bottom of the bed frame. That storage can used for clothing or other storage. They are from in a series of wood finishes and often come with shelves built into the headboard.
Which will act the way a seagull on an upper body makes the captain from being thrown out of bed suddenly throw with the ship. You do not have to make a high lip or even run the full length of the twin captains bed with storage. A common modern fit of this idea adds a short raised apron on both the head and foot of the bed leaving the middle of the side lower for easy in and expedition.
Use brass hardware on drawers. Maybe some brass angle pieces in the corners to resemble reinforcements on a treasure chest. And surround the bed with furniture that has a nautical theme-a bedside table that looks like a treasure chest, for example. A twin captains bed with storage is an alternative that would endure. So, the end.