Shipcard. Money is kept in your cabin's safe. Money is for shore, not used for daily, shipboard life. Except, maybe, the casino. It's conceivable, you'd only need money to tip the cabin boy when you arrive and when you depart.
And if you misplace/lose your card, hightail it down to the ship's office, and they will gladly replace (both) of your cards, disabling the lost one. This office is also the lost and found, which turns up a lot of stuff, sometimes a couple of days later, even. The courteous staff are very consistent with returning your card. Though sometimes it's hard to be handed your fresh drink, a card, and then sign your receipt. I usually have a camera dangling, too. I understand it's just me. But I'm gonna claim the Ship made me do it!
The Blues are the Facts of Life
The Home of the Blues is where you're playing it!