We use 2 cards while cruising. As someone else said, "If one is blocked use the other one until it's resolved." Both cards being a combo ATM/credit card from two different banks.

Keep enough cash aboard to get you through a couple of months of misc. expenses and use the cash. ( hide in more than one place on the boat). When you need to exchange currencies go to a place that will exchange the one you have for something local and again use cash. If you try to live by ATM's you're always looking for one. Not fun.

Work with a bank that has really good online banking. I really like Wells Fargo's online system. Pay all the bills through them with no cost. We've set up most important accounts to send us emails when a bill is due. When we get an email notice I go to the bank site, tell them to send a check and when to do it. Wells Fargo actually sends an envelope with a check inside on the day you tell them to. (cool and free). There's so much you can do online it's incredible.

You have to remember that all the hassle of blocking cards is for your own benefit. Hmmm? actually for the banks benefit as you have the right to dispute it as fraudulent and not be responsible.

RE the cash,,,, There are a lot of small safes that look like ordinary cans, some are even rusty when you buy them and are weighted to feel normal. I've seen an Ajax can like below that even has Ajax in the top part. They work great for keeping impt. stuff.