I have one of the smaller Humminbird down imaging units transducer mounted on my trolling motor.  Lately I will loose the signal when turning up the motor's speed. It never did this before. I thought it might be turbulence from the prop causing it, but the transducer is mounted forward of the prop.  Could it still be from turbulence? If so, is there anything adjustment wise I can do to the unit?  I checked the owners manual and the problem isn't addressed in it.

Unless you can run the motor in reverse, prop turbulence would not be an issue.

Typical RFI from the trolling motor. If you did not have it when first installed and are just getting it, there are several things that will cause the change:

Some are, worn brushes in the motor, bent prop shaft, out of balance prop, water in the motor due to seal compromised by fishing line, issues with the motor power connection, and damaged transducer cable.

Did you install the proper DI transducer for a trolling motor application? The transom version is not it. There are two DI trolling motor pucks that have extra internal shielding to help with possible RFI issues that the transom version does not have. Your unit model would determine which one is suitable.

Thanks Wayne.  I'm suspecting the prop as it's gotten beat up this season more than normal. I have the correct transducer including the protector. I had eliminated prop turbulence  for the reason you mentioned. I think I'll remove the prop and run the motor at 75% to see if it may be a harmonics or possibly the shaft.  

3 minutes ago, papajoe222 said:

Thanks Wayne.  I'm suspecting the prop as it's gotten beat up this season more than normal. I have the correct transducer including the protector. I had eliminated prop turbulence  for the reason you mentioned. I think I'll remove the prop and run the motor at 75% to see if it may be a harmonics or possibly the shaft.  

What kind of "protector" do you have?

The correct transducer is shaped like the larger one in this picture:

 

 

 

There are two of them on this motor: