Here's a thought. Fire is always a concern on a ship and dangerous things such as lanterns needed to be stored in a secure place, so that common sailors wouldn't use them carelessly while reading late at night in their hammocks or more likely gambling (before itty bitty reading lights). The door might have been reinforced with nails or merely pinned together with them as a plank door can be (with z-shaped planks on the back). Most nails I've encountered are dead, or at least mortally wounded. Any other thoughts?