I created the map for the game fairly early into development, even before I had a solid idea what I wanted from each room. It ended up being a great way to ground myself, lay out clear goals, and plot the progression. I created this detailed map based off of the real schematics for the NOAA Ferrell, and that realism lent itself to some amazing worldbuilding. (I did, of course, also include a purely text-based description of the layout in-game.)
Creating this detailed map was a small part of my larger goal to create a detailed, realistic, fact-based setting. I feel that emphasizing the details of reality helps suspend disbelief. Mythology doesn't feel real if you fudge or cheap out on the details of the real world; to that effect, I included as many details from the real Ferrell as possible. I did simplify the engine system to facilitate clearer and more easily-achieved goals, I added the vents and the pass-through cabinet to assist with quicker travel and a few puzzles. Also, technically the Ferrell is decommissioned, but these tweaks can be interpreted as saying that this is perhaps a NOAA Ferrell II.
The emphasis on mirroring reality had the fantastic side-effect of creating a problem: Skeleton research crew are a bit of a sci-fi myth. Real-world research vessels are densely packed with rotating crew lists: too many people to possible include in any individually meaningful way. Which gave me the fantastic opportunity to include the "Silencing of the Sleepers" puzzle in the prologue. While its initial purpose was to pare the crew down to a manageable size, this scene also served to start with a heavy emphasis on the alien descriptions and the human-monster disconnect.
The most obvious gift of the map was its practical purpose. I am somewhat young in the IF community, and grew up with point-and-click adventure games (and other kinds of games that always included a mini-map, like FPS or MMO's). I never developed a great ability for mentally mapping text-based cardinal directions, and so I always found the inclusion or creation of a map to be necessary. I created and included this map for anyone else who might be more like me when it comes to spatial recognition. Furthermore, with the use of someone alien descriptions for some of the rooms, I wanted to be sure that players had the opportunity to orient themselves if necessary.