I steady maps on mine on the boat in regular mode. It works fine, I have had it lockup in simulator. I can add waypoints and everything from there. I imagine it is running through its simulation routine and not starting over. So far no problems on the water and mine has been on several trips since Feb. I have had it on 5 tournaments where I worked many new waypoints over a 3 or 4 day trip. Though, I don`t use the simulator.