As i said in the cruise thread, I just got off one when i saw the news...
In my pocket almost all the time, the only time not was while I was in the pool and then it was in my bag by my chair was my Mission Wallet
http://www.bladeart.com/catalog/KnifeDisplay.aspx?MakerID=363 . In it was a few hundred cash, work ID ,CC,DL, health care card. In the outside slots were Fenix AAA led, Attwood Prybaby, Space Pen.
Clipped to me 100% of the time a Spyderco H1 serrated Drangonfly.
Not that big a knife but I had no idea what size they would allow so I went small and yellow,went through xray each day returning to the ship never an issue at all.
I was safer on that ship then at work, driving my car and so forth I felt prepaired and still would with same gear.
The biggest factors I feel are your conditioning , mind set, how you react under stress and so forth. I train hard almost daily,and preform well as a Lt on the FD 42 hours a week .
Edit. Deck plans are all over the ship ! Mine was 11 floors, all 11 floors were each on the posters showing all you'd need to know as far as I could tell.
Cruises are a safe vactions, safer then most of mine,white water canoeing in the Yukon a couple hundred miles from roads..... back pack hunting in 6 degree temps....
The biggest risk is to your bank account !!