On a cruise ship, isn't the cheap walkie talkies still a thing? Or did those die with cell phones?
For me the cell phone without internet is almost useless, not much I can do on it, might as well sue a purpose built device. They're also very cheap.
Even better if Nextel still worked on phones (but without service).
The boat could do a captive portal and provide it's own LAN?
> For me the cell phone without internet is almost useless
Projects like this one are a step towards fixing that. Personally I choose to keep both street and topographical maps of the entire continent locally on my phone. There are plenty of uses for a computer without a WAN connection.