Tried out my new 998c si today and am having problems with the depth readout and the water column in DI and 2D sonar. The depth reading will read right for a few seconds and then jump all over the place. The DI and 2D sonar are reading right for a few seconds and then the water column will go to 0. The SI seems to be working O.K., just the DI and 2D. The depth readout and water coumn jumping around don't happen at the same time if this makes any sense. My transducer is mounted on the jackplate and this happens at anywhere from 2 to 6 mph.
If anyone has any ideas that might help I would really appreciate it. If not I will call Humminbird in the morning.
Thanks,

bigminner