basson101,
There are several things that can cause this: interruption of power to the unit or low power are the main ones.
How is the unit connected to the battery, is this by direct wires or through the boat’s electrical wiring?
Is this happening along with some other event like when you hit a big wave or when you start the boat motor?
Some things to try and/or check:
Make sure that the power cable is correctly seated into the unit mount. When you press on the power connector with your finger it should not move downwards or around in its holder.
Check all electrical connections to be sure that none are loose or corroded. Be sure to check that the fuse is tight in its holder and is not corroded too.
Try very slightly bending the gold pins in the power cable away from each other. By slight here I mean so little that you cannot see the difference. This can add more or an interference fit between the pins of the power cable and the sockets of the unit.