Not sure I understand the question. I thought the whole point of using GPS on land was to provide real-time information on where to turn next to get to your pre-selected destination? On a cruise ship now sure how GPS would be of any benefit and thought cell phone reception is very limited once you are away from shore. Other than being curious as to exactly where the ship is currently located, not sure why you would need to know that. In the days before GPS, you would print out a map prior to leaving home and use those directions while driving your car to reach your destination. You would manually track your progress while driving.