I'm completely new to using fish finders.  Before buying one last month, I had never used one in my life.  I understand their value is more in depth/bottoms/temp, etc ...

 

I have a Pelican 10E (10ft plastic boat) with a 55lb trolling motor.

 

I bought a cheaper unit - a Lowrance Elite-4x.  I've used it about 10 times so far.  I run it at 200kHz and I'm typically in 5-20ft of water, but occasionally cross the river channel where its 50-70ft.

 

However, I've never seen a fish "arc" - not one single time.  Not even anything that remotely resembles an arc.  All I see are random blobs.  I have no clue if they're fish, trees, etc.  

 

Question 1:  Is this normal for boats that only use a trolling motor?  I read somewhere that the "arc" is a result of passing over the fish at high speed.  Is this true?  Did I just buy a crappy unit or is mine defective?  Or am I expecting too much from it?

 

 

I have my transducer mounted to the bottom of the trolling motor using the bracket & zip that came with it.  However, when I turn the trolling motor on, my sonar display seems to display a lot of interference.

 

Question 2: Is the prop interfering with the ping?  Do I have this mounted like an idiot?  

 

 

Thanks for any feedback...

 

Your mounting is fine.  The slower you go the less arches you will see.  Really slow the fish can look like flat lines.  You also have to remember that if fairly shallow your boat may spook them before you can see them on your screen.

Thanks Jig Man.. that's all I was wondering.

To create the "arch" affect, that takes time and distance of a fish within the sonar pulse.

 

If you watch the sonar tutorial on the Lowrance web site, it will show you an illustration of it.