I was going over the Wormwood's layout in preperation for starting the S&S campaign. I noticed that the only two stairs to the main deck from the lower levels are either through the officers' quarters or the captain's quarters, and both areas are pretty clearly off limits to not only the PCs but most NPCs. Not being a sailor by any means myself, how is the crew then supposed get to the main deck of the ship??
This appears to have been an oversight in the original artwork - if you look through the "GM Reference" thread for the Wormwood Mutiny module you should find several references to this.
In my case I added another companionway stair set into one of the main deck cargo hatches that connected to the lower decks and called it good. Having the entire crew have to troop through officers' country to get to work each day just makes no sense at all.
Good luck with the AP - it's a lot of fun! I'd suggest reading all the "GM Reference" threads before you begin, as the campaign can be quite deadly at first to unprepared players and a number of folks have suggested ways to improve, add to or modify the basic storyline that are quite creative.