Interference on fish finder

[FishinDinks]

I have a Garmin Striker 4 and I have it mounted to my Minn Kota Endura Max 55.  I am using the trolling motor as my primary motor on a Sun Dolphin sportsman 8.  This is a new boat and trolling motor I previously had the Garmin on my kayak and didn't have this issue.  Now the problem I have is any speed other then max speed i get this distortion on my Garmin.  I have the transducer mounted very secure with a hose clamp.  I am attaching an image of what it looks like.  I am assuming it has something to do with vibration.

 

Thanks in advance

[Jig Man]

It may be rf interference from the trolling motor.  Using a second battery for the Garmin will tell if it is or not.

[12poundbass]

I’d say it needs it’s own battery too. That’s what my stepdad’s screen looked like before he gave his Echomap it’s own battery. 

[FishinDinks]

It’s on its own battery

[12poundbass]

Interesting. Are the power wires together? If they are try and separate them. 

[FishinDinks]

The battery and wiring is the same one I used in my kayak. 

[MickD]

5 minutes ago, FishinDinks said:

The battery and wiring is the same one I used in my kayak. 

But the trolling motor is not the same.  I don't think it is vibration, but as others have said, electrical interference.  I don't know the electrical draw of your depth finder, but I used to take an old Eagle to Canada and powered it with one of those very compact batteries, like used in security systems, and it would last all day just powering the depth finder.  

[FishinDinks]

2 minutes ago, MickD said:

But the trolling motor is not the same.  I don't think it is vibration, but as others have said, electrical interference.  I don't know the electrical draw of your depth finder, but I used to take an old Eagle to Canada and powered it with one of those very compact batteries, like used in security systems, and it would last all day just powering the depth finder.  

That is what I am using. A 12v 7ah battery for just the fish finder. 

[Fishingmickey]

Does the interference go away when you turn off the trolling motor? Does the trolling motor come with a built in transducer? How close is the motor barrel to your transducer? Maybe try un-wiring the trolling motor and see if it goes away.

Good luck!

FM

[FishinDinks]

If it’s off or max speed it’s fine. It’s most of the speeds in between. 

[redmexican5081]

Is the TM grounded, not just connected to the negative side of the battery, but to an actual ground?  On bigger boats the ground is typically the engine block. I made sure all my batteries had a wire going back to the motor and my interference went away. I'm not sure what the ground point would be on a Sun Dolphin.