This is a photo of the safe I had in my stateroom onboard the Carnival Glory last year. Since the Carnival Conquest is the sister ship of the the Glory, the safe you will have in your room on the Conquest should be the same.
It operates by swiping a plastic card (with a magnetic strip on back) in the diagonal slot you see on the door of the safe. That will cause the door to lock. Later on, you would then swipe the exact same card again in that slot. That would cause the door to unlock, opening the safe. As you can see in the photo, you have about a shoebox amount of volume in the safe to store your valuables.
You can use almost any plastic card with a magnetic strip on back(credit card, driver's license,ATMcard, gift card, etc.). You could even use your Sail&Sign card, but they warn you not to use it. They say that it will damage the magnetic information on the strip rendering it useless (NOT TRUE, I learned first hand). Rumor has it the main reason not to use your Sail&Sign card to lock your safe is that it would make the safe vulnerable to a dishonest cabin steward who could use their master Sail&Sign card to gain acess to the safe. I don't know how true that rumor is.
They use this master Sail&Sign card on the job to open every stateroom door, in order to clean the rooms.
Anyway, I found that cards with wider magnetic strips on back work better with the safe. I first used my Kinko's Photocopy card on the safe (it has a narrow magnetic strip on back).I kept getting a "Card Read Error" message unless I swiped the card just right. I then used my Florida's Drivers License (which has a wide magnetic strip on the back). My Driver's License worked every time with no problems.
I had no problems with the safe during my cruise, and the valuable contents inside remained safe. Even when I naively used my Sail&Sign Card to lock the safe (before reading the warning not to do so). I also used the room safes on the two other Carnival ships I was on in past cruises, all with no problem as well.
I hope this was some help to you. Have a good time on your cruise.
My preference is a safe that you enter your own 4 digit number....with the card, you have to keep track of it...I've never had a problem with keeping things in the safe....and have never run into a dishonest room steward...Last cruise I had $200 in 20's fall out of the safe before I closed it...they fell behind the TV and I didn't notice it...I came back and there was a neatly stacked pile of my 20's....I gave one of them to our room steward when I saw her the next time....Have a Happy Cruise...
Outstanding response Frase. Everything you said is true. The Conquest (and all the Carnival ships I have been on use a magnetic strip reader. RCCL used a "pick a number" type safe and I can't remember for sure but I think NCL used a numbered safe also.
BUT, whichever the type, you can be sure that it is safe enough for most of your valuables. If you for some reason are carry a small fortune with you on your cruise, by all means ask the pursure's desk to store it in the ships safe.
I have always used my sign and sail card. I have never had it cause a problem with the card, but the drawback of doing so makes the safe only accessible by the S&S card used to lock it. So if I lock the safe and go have a drink, the wife can't get in to get her jewelry before meeting me. So, I have heard people using some old card (a used gift card works) and then hiding the card in the cabin somewhere.
Frase, I hope you don't mind but I am going to copy your answer for my FAQ section in the general cruise chat section...
Yes, Frase, most excellent answer. And great pic as always. I think one reason for not using the sail & sign card in the past was that it had your cabin number on it. They stopped putting it on there in 2005. If you lost your card whoever found it could open your cabin door and your safe. People do lose them, I found 2 on my last cruise and turned them in. I lost 2 on the cruise before that. Another reason may be that when the Purser makes a new card they close the previous folio to prevent it's use and issue a new folio number on the new card. Then the new card won't open the safe. So if I would have used the lost sail & sign card to lock the safe, the main Purser Officer would have had to meet my Steward and myself in the cabin and open it. Not saying that happened to me.
I think the safest card to use would be a gift card that doesn't have a name on it. We used one the last time. We had thought we would outsmart the safe reader and bring 2 identical unused gift cards, so we each could have safe access. It didn't work, it knew it was a different card.
I don't know all the reasons for not wanting the sail & sign cards used. They probably don't want us to know.
The suggested reasons for Not using a S&S card seem reasonable to me. I used the S&S card for many cruises until I cruised the Liberty and the S&S card stopped opening up my room and then would not open the safe either after my wife opened the room. Consequently I believe the reason that it can mess up the sign and sail card. I now use an old card and hide it in the room. It's easy and works very well and that way my wife and I can get into it even if the other is not there.