Fishfinder Display

[LDUBS]

Helix 7 sonar view. This is an old pre-CHIRP unit.

That clutter between about 25' & 40" was on the screen consistently no matter where I was on the lake. Also the less consistent one between 10' & 20'. I've not seen something like that before. I did a reset and it was still there. And, I was marking practically no fish in areas where I normally see them.

Any ideas what would cause this?

 

[Lost But Happy]

Thermocline?

 

[LDUBS]

Thanks. Could be the best explantation. I've just never seen this before. Consistently ranging from 25' to 40' seems like an awful "thick" thermocline.

 

[DaleH]

Wow, my Furuno deep water units would only show a thermocline as a white line. I think you might be best to sent that photo to Humminbird.

The only thing I can think of is that you might have your unit optimized, in it’s settings, for ‘shallow(er)’ water work. Can you change the transducer frequency/angle on that machine?

 

[Still Afloat]

Check for loose connections if you haven’t already done so. It could be as simple as a loose power or transducer connector.

 

[LDUBS]

Check for loose connections if you haven’t already done so. It could be as simple as a loose power or transducer connector.

I did disconnect t and reconnect the transducer and power cables at the back of the unit. I should probably check for any bent pins and make sure the power connections at the fuse and battery are secure.

 

[LDUBS]

Wow, my Furuno deep water units would only show a thermocline as a white line. I think you might be best to sent that photo to Humminbird.

Sending the pic to Humminbird is a good idea, thanks. I see they have a customer support form that allows attachments. This unit is far out of warranty so I hope it is some simple explanation.

I'll post back with what they say.

The only thing I can think of is that you might have your unit optimized, in it’s settings, for ‘shallow(er)’ water work. Can you change the transducer frequency/angle on that machine?

My HB owner's manual says thermoclines will show up as a band of many colors. In the sample display it is a narrow band (a few inches). Nothing like what I am seeing.

It isn't set for shallow water as far as I know. This was occurring in depths of anywhere from 60' to 200'. On standard sonar I can select 455 KHz or 200 KHz. I'm pretty sure it is set at 200 KHz. I wish I had thought to try the other frequency. By the way, while I never use down imaging I did switch to that mode and the same wide band occurred there too.

 

[Lost But Happy]

I'll post back with what they say.

 

[LDUBS]

I heard back from Humminbird customer support. A quick response and they provided a toll free phone number should I want to call them next time I'm out on the water. They also suggest a thermocline and provided a link with more info. It will be interesting to see if I get a similar display next time I'm out on the lake.

Below is a copy of the verbiage and some thermocline images from Humminbird:

SEEING THERMOCLINE​

Updated 6 months ago

Ensure the unit is in Sonar Mode. Increase the sensitivity to view a weaker sonar reflection from the thermocline. The temperature difference has to be great enough and changed quickly enough vertically to display as a thermocline or it will not reflect the sonar signals. Since the density of the water changes with it's temperature, the sonar signal will reflect off the change in water density. The change in water density creates thermocline. Examples below show what thermocline might look like.

 

[Lost But Happy]

Well Ill be.