Have you set your keel offset?
Here is what you have to remember, the transducer is at the bottom of the hull....not at the waterline. So, typically, you have to program in an offset into the instruments to accurately reflect the depth under the waterline...otherwise your depth will be under-represented and you can have freak-out momemnts. The only way I was able to do this was to measure the distance from my hull where the transducer was to the water stain where my waterline was, then put that value into the instruments. I've also used a handheld depth sounder at surface then programmed in an offset using that vs what my instruments were reading.
Of course check all the connections and the transducer to make sure they're working...but my bet is that your offset is not established.
Last edited by night0wl; 12-02-2011 at 10:15 AM.