lowrance problems

[jpeff31787]

Alright guys, I tried not to post on here about this, but figured it would help me fix this problem faster. I have a gps/sonar that always turns off as soon as I hit a wave. If its calm and not wavy or bumpy, its fine. I already took the wires connecting to the battery off and sanded them down. No luck. To check to see if it was a short, I've fiddled with the wires on the back of the unit and I've shaken the battery up to see if that would cause it to turn off, and neither made it turn off. I really don't know how to check for a short in the wire, since it only turns off as I hit a wave. I don't want to be 20 miles offshore with no gps either, so I kind of need this fixed and fast.

I'm kind of at a loss, the only thing I can think of is it may be a fuse somewhere?