I lay some pre-made grids over the storyboard panel and adjust them with Photoshop's perspective tool. I eyeball it this time instead of using vanishing points.
The horizon line (dark blue) is near the top of the frame so we look down into the room.
Then using the storyboard as a guide, I rough in the architecture and major elements.
Though I used reference for the pirate ship, it's a theater stage, not a seafaring vessel, so I cheated a lot of the logistics of a ship.