WiFi sniffing is one of the least productive methods for hackers to compromise your account. First, they have to be almost in the same room (WiFi doesn't travel that far,) have some software that would seem curious in an internet cafe, and be able to spend quite a bit of time hanging out waiting for the person logging into their bank account or business account.
While you say it may be one of the least productive methods, it is still very easy to do from any car parked right outside of a cafe or boat just outside of a marina lounge.
Far more productive is to sit on the wired side of the connection (i.e. the connection from the cafe to the rest of the internet.) Using the same tools that are used to debug Ethernet connections they can read 100% of the traffic.
Yes, this is a reason why I am particularly worried for cruisers who pick up wifi somewhere on the icw or in some anchorage and just go ahead and use it to log into their email. You have no idea who is hosting that wifi signal and they may be data logging. Just lose your email account first, then then it can be a slippery slope to your other personal information. I use a VPN all the time now. It's a hassle, but *much less* of a hassle than losing my identity!
So far I've seen these specific recommendations presented for increasing your security while online while cruising:
Use HTTPS as often as possible
Use a cellphone based internet connection rather than wifi
Use a VPN
Using virtual card numbers and credit cards rather than debit cards are very good ideas. thanks.
Let me just say that keyloggers scare me, and I never use anyone else's computers to check my accounts any more! A key logger can be as simple as a small usb thumb/flash drive plugged into the back of someone's computer like at the library or that open terminal at the marina!