First this unit is mounted on a pontoon boat the motor is clear of trans..
I just mounted this unit and I see it needs some adjusting I set it to shoot 1 or 2 degrees forward and level side to side with my boat..
I assume it's possible when I set in the boat it is lower on the right side and signal could be hitting the surface of the lake and not retuning correctly. It Blacks out about 1/2 of the side imaging distance no matter what range I set it at..

I see it's picking up my bilge pump which is mounted on other pontoon but I don't that could cause the wavy black shadow.
The right side image looks great.




I appreciate your advice.

Post a picture of your transducer installation and the whole back end of the boat.

Thx for responding Wayne I'm downloading pics now...

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The signal is hitting air and causing that. Most likely due to the prop exaust and wash.

that's what i was thinking. try to put your transducer on the front.

It looks like you were close to shore on the left side. The clearance across the back of the motor looks good in the picture.
Do you trim out some when running on the water?
Having the SI range set to 125' means you were around 60' from shore with the shore on the left side.

It cannot be the exhaust or "wash" as they will reflect sonar pulses and be displayed as a blurry line in the water column.
You have two close object echos on the left side of the centerline.
One of those is the left pontoon and the other may be the outboard.

Next time on the water, set the SI range to 3 times the depth so you can get a better idea of what the close object echos are.
You can also see those lines on the DI view and get a better measurement of the distance from the transducer.

Thx Guys.
I'm still working on it I'll snap more pics next time out...
I do see the lines near the surface that could be thrust from my motor or possibly even the other pontoon but the black line is well away from the boat.
I should have added a little more info...
On my pontoon I always run motor completely trimmed down/in unless I happen into shallow water..
Yes, I thought it looked like a false shoreline or bottom but actually it's on the side towards deeper open water but no matter which side is deeper the wavy black shadow stays on the left side of the SI that's why I thought it may be bouncing off the surface , also the right side bottom seems stronger or brighter with more detail than the the left wavy side. I will try changing the SI distance and try some diff water depths,I don't utilize the DI much but I will study it as well. I haven't had a chance to use the unit much yet.

I noticed while running back and forth under a bridge in 20 fow that the pillars didn't look right either it just didn't have the detail I have seen b4 that the 898's can draw, I assume the 899 should be at least as good with the HD trans. I up graded to. I ran by boat docks and you could easily count every post on the right side but the left didn't have the same detail.
I need to drop it a 1/4 inch because I loose or get a weak bottom readings at around 15 mph also I thought I could try and tilt it slightly..
Also it maybe crazy but I thought I may take a bubble level out next time and find what angle and pitch of my boat operates at while graphing at 3 mph...

I hope to get out again soon as weather cooperates, thank you again for any advice.

Does your pontoons have the angled V shaped "runners" welded to the bottom of them?
If so, you will have to lower the transducer about another 6" or more to get below the disturbed water that it causes.
The transducer installation instructions describe what to avoid to get good depth performance?

No they don't the pontoons are large so boat planes easily but they are smooth and rounded.