So, a) how long could she go without drinking something, and b) what would be the results beyond the obvious of her only liquid being alcoholic for a couple of days?
I tried googling "drinking alcohol as only liquid," but didn't come up with a whole lot, and I'm having a hard time phrasing a good query for this one.
ETA: To clarify, I did research at least some of the myriad mostly decrepit ships that were put into service to ferry the thousands of gold seekers at short notice, and it's entirely plausible that she's in a ship where the cargo area is divided into sections that can be closed off, and she's trapped in one where there isn't any water. No, she doesn't have access to salt water, either, or the means to distill it. And for all she knows she may end up being stuck there until they reach Skagway and the ship is unloaded (a trip that can take up to a week).
And, yeah, I've taken into consideration the, er, sanitary (or not) facilities [g]. And she's definitely getting a bit battered by her surroundings.
She's not used to alcohol herself, although she does know about its effects, but I think one drink is probably going to prove to her that it's not helping.