Post reveals how much you should tip cruise ship porters (it's more than you think)
While on your cruise ship, the only acceptable form of payment for drinks, souvenirs in the shops, specialty restaurants, etc., is your cruise card. At the end of the sailing, your onboard account will be settled using the payment method you provided at check-in.
Plus, with cruisers having the option to pre-pay their gratuities before sailing or automatically charge them to their onboard account, new sailors often wonder how much cash they should bring.