Ardurover Initalizing

Hello to everyone.
I have a boat with Ardurover 4.0 installed. When I start the boat in a fixed place on the shore, it works normally. But, when I put the boat in rough water and try to start it, “Beginning INS calibration. Do not move vehicle” gives a warning and it is always waiting in ‘Initializing’ mode and the card does not start. How can I overcome this problem?