Topic: 998 won't maintain bottom reading

[wasteman]

I recently purchased a 998 unit (about a month ago) and have not been able to maintain a steady bottom reading.  The bottom readings jump from 4 feet to 80 feet.  I am running the Susquehanna River which is shallow and rocky and until today was pretty muddy.  I was thinking maybe the dirty water was contributing to the issue or a possible mounting height issue.  I was able to get out today and make multiple adjustments with no success.  The area I was in had bot shallow and deep water and I was not able to hold a steady bottom reading.

The side imaging is working.....Do I have a bad transducer?  I tried surface clutter as well as restore factory defaults.

Thanks

Waste

[newkid4si]

When I originally installed my 998, I would lose bottom reading as I increased speed. I was able to correct that by lowering the back end of the
transducer about 1/4". My guess is that your transducer is OK as you have SI. Probably a location or adjustment issue.
Sonar is not normally affected by off color water. If there are a lot of particles in the water, that can cause some strange readings.

       Mike

[Trout Bum]

I had a similar problem, especially on rapidly changing bottom depths.

Bird CS said to set the max depth at a depth a little over what I expected to be fishing in. By doing this the unit will not be looking from 0 ro it's max limits for the bottom.

This solved the problem for me, now I hardly ever loose the bottom.

If your fishing in say a max of 100 feet, set the bottom for 120 or 150.

To make this setting go to the Sonar Menu Tab/Max Depth and change from Auto to somewhat over your max depth. Actually I had mine set around 300' for most of last year without any problems. I'm usually fishing in depths anywhere form 10 to 250' deep.

[wasteman]

I'll give the depth setting a try.  I am fishing hard rock bottom which is typically shallow (rarely over 15').  Most of the river is 2-6'.  Does the boat being aluminum cause any issues?  I've rigged up many Fishfinders and am confident my transducer set-up is correct.  I did adjust the angle pointing down and up a little as well as flat.....

Thanks for your insights, I really do not want to return the unit, it is a PIA to run all the wires and what not

Waste

[rnvinc]

Can you post pix of your xducer installation...both from the sides and the rear..(and at xducer level)...??

Is there a shoot thru xducer and AS SIDB Y cable in this setup...??

Rickie

[newkid4si]

   "Does the boat being aluminum cause any issues? "
 
    Mine is aluminum also and after I got the correct adjustment, I've been good to go.

          Mike

[Humminbird_Greg]

Waste,
Do you get good bottom depth readings at any time or is this only when running at XXmph or faster?

[wasteman]

I went out again today and this is what I am experiencing:

At slow speeds <10 MPH I am getting and maintaining bottom.  If I anchor the bottom reading fluctuates.  When anchored in 3 feet of water I was fluctuating from 2 to 8 feet.  In deeper water the fluctuation was more dramatic.

I could maintain bottom up until 16 MPH (pretty much when I got on plane).

I adjusted the angle of the transducer (reaching down and angling the unit more up & down) and did not see any appreciable differences. 

Attached are a few pictures of the display.  One question is there is a line that appears to be a temperature line at the top of the screen, is there a setting to get rid of this?

I am speculating I need to adjust the unit down to get the bottom reading when on plane BUT I really fear that lowering it will put it in harms way.  I am a irritated that I cannot hold bottom when I am anchored, I cannot imagine that the position should impact that.  One other twist, my boat is a jet with pods.  The Pods angle slightly up from the bottom of the boat.

The side imaging appears to be working but I really can't tell what I am looking at to tell for sure

Thanks for all of the help....I am bordering on taking this off and returning it for a "simpler" unit but have really wanted a quality FF for a long time....I've mounted a lot of transducers and have never had an issue like this.  She is actually mounted in the same spot as my previous Humminbird unit....

Waste

[wasteman]

Trying to post pictures....I'm thinking I should have no technology....

[wasteman]

Ok, I've got this down...(uploading pictures....)

Attached are shots of transducer and the readings I saw today.

Thanks for your insights

Waste

[newkid4si]

"One question is there is a line that appears to be a temperature line at the top of the screen, is there a setting to get rid of this?"

  This is probably the Temperature Graft.
  From the main menu--- select Sonar---tab down to Temperature Graft (near bottom)--- default is "on"--- turn to "off".

           Mike

[sfw1960]

Why did you upload PDFs instead of JPGs??
  LOL!!!

Looks like the whole XDCR is a bit LOW (move it up at least 3/16-1/4") and you need to drop the tail end down about a quarter inch or so from what I see - Rickie??
What ya think???

Robert

[rnvinc]

Definitely don't give up...most issues can be worked thru...

I'm thinking that the hard rock bottom is causing the pulse to reflect several times from the rock bottom to the surface and back down again..and may be confusing the unit...

Try setting the "Beam Select" menu under the Sonar tab to 200kHz only...
Set the Switchfire to "Clear"...(if it's not already)...
Then exit out of the main menu...
Then open the Xpress menu (while viewing the Sonar view)..
Start backing off the sensitivity to see if the depth stabilizes....

I realize this is not the optimal way you would normally want to use the unit in your waters...but it may give us an indication that the issue is just the extra hard bottom causing double reflections...

BTW....what software version is in the 998...?? (Some of my older 1197 versions had trouble with shallow water depth that was fixed in a later software version)...

Also...you might think about an additional XTM 9 20 Dual beam and the AS SIDB Y cable in order to keep that expensive HDSI xducer up a little higher on the boat for protection...

Rickie

[newkid4si]

Rickie has a great suggestion in the backing down on the sensitivity. In that shallow water/hard bottom situation, I think that will go a long way
toward solving the problem.

          Mike

[sfw1960]

no opinion on the actual mounting Rickie>

[Humminbird_Greg]

That transducer does look low Robert but it may need to be that way due to the sloping pod it is mounted on.   Would have to be there seeing it run through the water to be sure.

Let’s back up a bit though:
Waste you stated “If I anchor the bottom reading fluctuates.  When anchored in 3 feet of water I was fluctuating from 2 to 8 feet.  In deeper water the fluctuation was more dramatic.”.
If we can’t get the unit to read while anchored or drifting, it will not read correctly while at any speed.  So let’s concentrate our efforts there first.  With everything else on the boat turned off; reset the unit to the factory defaults and see if it will read the bottom correctly.  If not, try setting the Surface Clutter menu to a lower numerical setting (filtering out more of the Surface Clutter).  If that does not help try also setting the Water Type menu to the “Salt (deep)” setting (I know, this sounds weird).

If that does not help, see if you can find someone else that is running a non-DI model Humminbird unit and test their unit on your power and transducer and your unit on their power and transducer.  This does not have to be another 998c HD Si unit as most models use the same 200/83kHz 2D sonar.

[sfw1960]

Great advice, as always Greg!

[rnvinc]

no opinion on the actual mounting Rickie>

I've not seen very many pod mounted xducers....

I'm still thinking an additional XNT 9 20 and the AS SIDB Y cable would better protect the HDSI xducer and allow the XNT 9 20 to get the 2d readings...

But...If Greg's suggestions work...wasteman might be just fine....

Rickie

[wasteman]

I purchased and installed the high speed transducer and Y cable.  Reset the unit to factory defaults and tried the different suggestions with no luck.  Interestingly it seems I can hold bottom if I am moving slowly, once I get on plain (15 MPH) I'm losing it.  Interestingly when I change the water type to Salt Water Deep the unit reads much deeper than the water I am in.  Example I'm in 3 feet and when I change the water type it jumps to 20 feet.  It also seemed that playing with the surface clutter the depth reading would fluctuate.

I unhooked the side imaging transducer so I was only seeing the new "high speed" transducer and the results were the same....

Unfortunately I do not know anyone with the same or similar unit to test the actual head....any thoughts...is it time to give up?  I believe I have 90 days to return before I am stuck.....

Thanks

Waste

[sfw1960]

If this is a new unit - let HB fix it for you....
If used, I would say return it - not knowing what you paid - I know a new one can be had for under $1200

[Humminbird_Greg]

Waste,
Changing the Water Type and/or Surface Clutter menus affects how the unit filters the sonar returns that are at the surface or near the surface.  It helps in some locations but not all.

If you are only losing the correct bottom reading when the boat is in motion than it is either a transducer installation issue or it is a noise issue.  You can check for boat motor interference by revving the motor while it is out of gear.  The sonar should not change and if it does that may indicate motor noise is the cause of the problem.