How does a transducer work when mounted on a trolling motor? I understand the transom mount because it's relatively stationary. But if the trolling motor is constantly moving  on axis, how do you get a side image or accurate down image? Or does it only work when the motor is still?

l don't think down image would be affected since it is not "directional" and its depth is constant, but not so for the side image.  I doubt if side image will work well for the reasons you state.  Not moving, rotating, etc.  

 

The Ulterra motor, with which I am familiar, carries a transducer doesn't support down or side imaging on my Helix 7.  I think you'd have to mount a separate transducer to the motor.  I have the choice of reading the motor's transducer and getting only regular sonar or using the mega transducer on the stern and then getting side and down data from the rear of the boat.

 

Perhaps an expert on this will chime in.

I'm no expert at all, but I've talked with Wayne P about SI on a trolling motor. He said he uses it and it works just fine. He also said that there is some distortion when you move your TM but quickly clears up. If you're constantly moving your TM around say on windy days or have it in "anchor mode" or "spot lock" and it's always moving you're going to be disappointed. If you're drifting, or cruising along on the same course with an occasional adjustment of the TM it's going to work just fine. 

 

Again I'm not expert, this is in a nutshell the conversation Wayne P and I had.

Thanks guys. That's kinda what I figured. I appreciate the reply.

There's plenty of guys using SI on the front.

The trolling motor is not constantly moving. It only moves when you move it. The biggest issue with a trolling motor mount transducer is RFI. Getting rid of it can be a bit frustrating. If you do choose to get SI and fish shallow water,  may I suggest you investing in a TSS transducer shield and saver.

Excellent advice ^^^

On 9/27/2017 at 8:04 AM, MickD said:

 I doubt if side image will work well for the reasons you state.

Side Imaging works fine on a trolling motor, I ran it that way for years.

 

Yes, it distorts when the motor pivots...but how often do you need to do that at the same time you'd be using SI anyway.

On 9/27/2017 at 11:49 AM, 12poundbass said:

I'm no expert at all, but I've talked with Wayne P about SI on a trolling motor. He said he uses it and it works just fine. He also said that there is some distortion when you move your TM but quickly clears up. If you're constantly moving your TM around say on windy days or have it in "anchor mode" or "spot lock" and it's always moving you're going to be disappointed. If you're drifting, or cruising along on the same course with an occasional adjustment of the TM it's going to work just fine. 

^^^^^This, exactly.^^^^^

 

As an interesting side bar, more than one person with trolling motor mounted SI used it as a sort of directional "360°" to scan ahead of the boat...

 

360° mounted to a trolling motor shaft does a much better job, but it wasn't available right way...

 

After running SI on my trolling motor for years...I decided I didn't really need two SI transducers on the same boat and when I re-rigged this spring, I went DI only at the front.  I don't miss it at all.

 

For me, SI is for searching for structure, and I'm fine doing that off the back of the boat.  When I'm fishing up front I usually already know what structure I'm on and I don't need it.

 

...in my case, if I decide I need it, I've got 360° to scan all the way around the boat, even if I'm stopped.