Startup Idea : Disallow a specific cellular network

I've seen plenty of phone data management apps out there but none have a feature that would allow your phone to remember NOT to connect to a specific cell network.Let me explain:When on a cruise ship if the ship is within 12 miles of land they supposedly turn off their cellular network, however, we've been on cruises where we're a bit further out than 12 miles and still get a good cell signal. Problem is that if the ship's cellular network is on and your phone is rebooted or turned off/on it will very likely auto connect to the ship cellular network. You might not realize it until it's too late and lots of $$ later! It would be nice to have a feature to disallow a cellular network connection in this case (ie: ship cellular network).