When I start my boat my front sonar/gps shuts off. It's a real pain to have to turn it back on and have it re-search for satellites every time I start the boat.

The unit is a Lowrance 522c which I put on this year. The former unit was a Garmin 160, it never did that. It's running on the same power wire as the 160 was.

Any ideas????

Did you blow a fuse? :-?

You have a bad battery or bad connection at the battery.  The current required to start the motor is making to great of a voltage drop.  To check it, place the leads of a good DVM across the lead terminals of the battery crank the motor.  It should not drop below approx 11.5 volts max.  Now place the leads on the wire connectors on the battery and crank it again.  The voltage drop on the cables should be no more than the battery, if it is more, the connections are dirty/bad.  

Another thing that will cause this is using a deep cycle battery as a cranking battery.  They are not designed to deliver tha amps required to crank the motor and will cause too much voltage drop.

I had an a Lowrance 350A and it did the same thing all the time, un-till I had to put it on a different battery. Now my Humminbirds never had that problem

When you start your motor, monitor your battery voltage. I would bet it spikes to around 18v which is the overvoltage protection limit and the unit shuts itself off.

You have a bad battery or bad connection at the battery. The current required to start the motor is making to great of a voltage drop. To check it, place the leads of a good DVM across the lead terminals of the battery crank the motor. It should not drop below approx 11.5 volts max. Now place the leads on the wire connectors on the battery and crank it again. The voltage drop on the cables should be no more than the battery, if it is more, the connections are dirty/bad.

Another thing that will cause this is using a deep cycle battery as a cranking battery. They are not designed to deliver tha amps required to crank the motor and will cause too much voltage drop.

Here is your problem...........

Thanks.........

Prior to reading this I checked my terminals and found some corrosion. I cleaned up the terminals and connections. I also found the wing nut had worked itself kinda loose. After the clean up and tightening the nut I turned on the front unit, cranked the motor, the sonar/gps stayed on, problem solved I believe.

Yes, it has a fuse.