All tourists will get a ship card when they board the ship. The ship card is not only the identification of the ship (the passport was taken away), but also the key to the room (similar to a hotel) and the personal account for the ship's consumption.
If an individual does not have a dual-currency credit card, he/she needs to charge cash into the personal account of the ship card as the stored value (also called deposit) for your consumption on the ship. Anyone who needs to pay can swipe the ship card to deposit in the consumption account and settle the account before disembarking. The cash withdrawn is only USD cash.
If you have a dual-currency credit card, you can directly associate (bind) the credit card with the ship card, and swiping the ship card is equivalent to swiping the credit card. There will be bills to check before disembarking. No problem to sign. Compared with the previous cash stored value form, it is more convenient and faster to check out without one party.