About this, is this something you need to seek help with, with your own bank maybe before you go?
As most people are aware, that currency on the ship is $$.
I'm from Belgium, when I went to America (twice), I had to go to my bank, and they had to activate my VISA for being used in America, otherwise I either couldn't use it, or probably like you are saying, it would have gotten blocked with so many $$ transactions instead of €€.
When I moved to the UK, my VISA company was picking up lots of ££ transactions, but this time, my bank hadn't told me I needed to do something specific with that as it is in Europe (and European Union at the time), but still my VISA company blocked my card due to all the ££ transactions.