I think that a captains log would be a fun piece to add to the ships.
It will register (for example)
- The Island you passed
- The Island you stopped
When you have stopped it will also register what you cargo bring on board, or off board.
The captains log can be read at the map table, or when the ship is destroyed it will float to the surface of the sea for a short time. It then can be destroyed by it’s own crew or picked up by the winning crew.
I for example stash booty somewhere out of sight when I am starting on my own, so when my buddies come online they can get the loot and experience. And when I get attacked when I am alone and I lose the fight, probably, I don’t lose all the treasure. When the crew that sunk me finds out that I stashed treasure they can go on a treasure hunt of a different kind.
There are probably more things you can do with a captains log, but this is what came to mind