Topic: Seeing interferance in the water colum

[Jeffray]

I just mounted my 1198 SI and cant get a clear water column on the motor side? It looks to have plenty clearance from the motor and Jack plate? I just moved my 798 from the rear to the front, it had the same issue and now that it is on the trolling motor it has the best images it ever had..not distortion in the motor side water column.  Any ideas or suggestions on my mount set up?
Thanks

[Humminbird_Greg]

Jeffray,
Is there anything else on the transom to the left side of the motor?
If not, than it sounds like you may be picking up a sonar reflection from the jackplate. Try and lower the transducer to counter this.

Post a Screen Snapshot of what you are seeing on the left Si sonar.  Include one with the SI Range set to 20 feet.

[Jeffray]

Thanks for the reply Greg! I am including another picture from the left side, as you can see it shows nothing else there? You suggested lowering it a bit, my question to that is this...I had it a little higher first trip out and it was losing bottom at 9 mph, lowered it approx 3/16 to 1/4 inch and now it keeps contact but throws water up the side of the motor? Would lowering help that problem also?
As far as the screen shot i will get that tomorrow, planning on being on the water so i will post that as soon as i can.


THANKS for your help already

[Jeffray]

another view

[Jeffray]

One more...tried to add these to one but they were to large.

[Humminbird_Greg]

It looks clear to the left side of the transducer except for what looks to be a metal shed… I’m guessing that you don’t take that with you on the water!

You must be getting sonar reflections from the left side of the jackplate then.

This is not a good location for any sort of high speed depth readings.  You should look into getting an XP-9-20 inside-the-hull DualBeam transducer and an AS-Si-DB-Y transducer splitter cable for that.

Looking at your pics again, I am wondering if moving the transducer over closer to the jackplate would help with the left Si sonar reflections.  The farther away from the transducer you get the higher the Si beams gets, so moving closer could possibly put the left Si beam below the level of the jackplate plus there are some near-field filters that would be able to help with this (internal programming stuff that you cannot adjust).  Get any marine grade double-sided tape to test this with at low speed?

[Jeffray]

You guesses right the metal shield stay's with the trailer  I looked it over this evening to see how much i could move it toward the jack plate, right now its 5 inches from it. Also the water intake cover is in the middle of that 5 inches so that would prevent the move. To put it below it that would put the transducer 2+ inches below the boat.

Those near field filters you mentioned....are they down loadable ? Would it be an option to mount it in the middle of the jack plate? I could make a bracket to get it down lower? That would get it in the middle and shoot both sides but would it work there with the cut out in the boat ( pict 1 )?

Thanks again for the help, I appreciate any idea's you have!

[Humminbird_Greg]

Those near-field filters are a part of the software code that we can’t get to.  It would be nice if we could as it would possibly (I’m guessing here) allow someone in your situation to adjust the sonar returns of the jackplate out.

Are you sure that there is not enough room between that water intake screen and the jackplate for the transducer?

Not sure how well it would work if mounted in the middle of the jackplate with it being lowered.  At some point it could start interfering with the water flow to the intake of the motor or to the propeller – neither are good things for your boat.  If the jackplate were longer it would work in the middle of it but right now I don’t think that it will fit right there (just slid over from where it is at now) without being hit by the motor when you tuck it in to blast off.