If you all have iPhones - the iMessage protocol will likely be functional through the ship's WiFi, even without internet plans, so you could message just as you would a group message on land.  My Android phone was also able to receive text messages on the Escape in March, even without being online on internet (I was connected to ship's WiFi, just not logged in for internet access outside the ship)   You could just plan meeting locations and times.    The in-app messaging in t