Long time reader first time poster. I am praying you guys can help. I have been working with several other people on a couple of different forums for about a month now trying to trouble shoot my 798 hdsi. I have about $1300 invested in a single 798 head unit with separate transducers at the TM and the transom/console. I am begging for a solution to several different issues. I am ready to give up on Humminbird if something does not give. It should not be this difficult.

1. I have the transom mounted ducer installed per directions with no obstructions in the way. When traveling at low speeds (UP to 3 mph) I always get a "white cloud" in the top 3 feet of the left side column and most times I lose some the outer image of the right edge. This cloud and missing gets bigger and occurs on both sides of the column at speeds above 3 mph and the whole screen goes static. This happens regardless of whether the TM or the engine propels the boats See pics.
Low speed

Shield placement. I have since even removed the livewell screen just in case

High Speed creates static

I put the ducer on a stick deeper in the water and saw this at low speed.COuld not keep it steady at high speed.

I put the whole system on separate shielded wires and on separate dedicated batteries away from all other electrical sources thing bad grounds or interference/noise was causing the problem but it still does it. Notice in the pic below how you can see where I back on and off the throttle to make the screen static in and out and white clouds get big and little. IT affects the Di and @D as well.


2. The list of similar problems I am having at the TM are too numerous to mention. I will address them if and when I can address the issues above.

3. I borrowed another 798 that works and tested on my system but same probs occurred. We noticed that when running my 798 on transom and borrowed one on TM caused repeating patterns of alternating black and white lines on both screens which went away when one is turned off. CRAZY

Please help. I have tried it all but maybe some one can help. I have a 20 foot express hd aluminum boat.