Topic: Is My SI Transducer Set Properly?

[MTBob]

Finally... I spent some focused time on the water using my new 998c SI.  And... I finally figured out how to take snapshots.  So, here is my opening question relating to positioning of my SI transducer.  These snapshots were taken after my initial transducer positioning.
One interesting aberration is the apparent squiggle line on the right side.  I believe that is the image of the prop from my 9.9 kicker.  Looking at my rear end (the boat that is), I have the transducers on the left (port), main engine, and the kicker on the right side (starboard).  Tomorrow I will set the 9.9 engine up a notch on the trim and see if the "squiggle" disapears.
Does this SI image look correct?


Here's another image:

and one more.


It appears to me that the right side has a lighter shade - but I'm not too sure if that is appropriate.  If not, should I adjust the transducer?
Thanks in advance,
Bob

[rnvinc]

If one will notice that the "squiggle line" (as you call it)... Displayed at the corresponding distance from the centerline (xducer) when the SI range was decreased from 95' to 31'....this is a clear indication that blockage is the issue ...and not RF or xducer malfunction...

Trimming the motors up should determine if it is blockage...

I think you will find, over time... that normal sonar echoes are rarely going to be that close to the centerline in the SI image anyway...and that "squiggle line" will not be in the way of your everyday sonar operation....and maybe just not pay attention to the "squiggle line"...

Also...the 1st image shows good equality in brightness left to right ....but the second image shows the right side as brighter...this could be just a difference in bottom inclination from xducer or bottom composition...more testing and screenshots will help determine if this "right side brighter" is a re-occurring factor of if it is just a variable in enviroment conditions...

I would not move xducer until more testing is done...

Rickie

[Humminbird_Greg]

It’s hard for me to tell from the screen snapshots you posted MTBob.  I can’t zoom in on them without losing resolution.  Post the next ones as an attachment and it will work better for us.  I would like to see a screen snapshot of that “squiggle line” with the Si Range set to 20 feet.  Try to get a screen snapshot in shallow water (less than 10 feet) that is in a flat area to help compare the left versus right side.  Try to notice if the boat is level when you are at these speeds while on the water.  Depending on the boat and the size of the backend (the driver, not the boat!) it may not be level and could help show one side brighter than the other.  You really need to get rid of the right Si sonar blockage first before comparing though.

[MTBob]

Thanks Richie / Greg for your comments, great help.  As Greg suggested I'm resending the snapshots as attachments for better resolution.  I am also sending several more snapshots for additional reference.  Surprisingly, it appears that the SI works at speeds up to about 25 MPH.
I will be traveling to a different lake today, likely without WiFi for a while. 
Based on the "squiggle" that I see in the SI view, I think I'll raise the 9.9 kicker one trim pin and see if that makes a difference.
Thanks for your replies, very helpful.
Bob

[rnvinc]

I have read reports from Jasen Halfen at  http://www.jasonhalfenoutdoors.com/ ....that he has been able to obtain SI readings up to 40 mph but not at good detail...

Xducer placement is key...

Rickie

[MTBob]

Here are some additional SI shots after moving my 9.9 kicker up one trim pin notch.  This appears to have helped minimized the "squiggle", apparently from the motor's prop, but hasn't eliminated it completely.  At this point in my SI education I don't find this to be a problem.  If you recall my transducer mounting system http://forums.sideimagingsoft.com/index.php?topic=5286.msg33399#msg33399, I can raise or rotate the transducer to adjust it.  So, if I need to make some adjustment, I can.
I think the boat is sitting about as level as it can.  I've got the 9.9 kicker on the starboard side, so with my wife sitting on the port side (aka "ballast"), the boat is generally trimmed.
So, take a look at these shapshots and see what you think.

[rnvinc]

The first 3 shots are a little more dark on the outmost right side than the left...

Was the bottom falling off into deeper water to the right of the boat...

Also.. It would good to try and capture some structure in a few screenshots to give reference for diagnosing Chart Speed and other settings...

Also..it would be good to get some comparison shots of the 455kHz setting vs the 800kHz setting...

Rickie

[MTBob]

Thanks Rickie.  I hope to be fishing again next week in some unusual terrain.  I'll try to get various SI snapshots and see how they look.
Bob