Thermocline on structure scan

[21 Elite]

Is it possible to see a thermocline on side scan down scan? Or a cold under water spring will it show up on down scan as a foggy layer on the sonar? Hope this makes sense

[striperjohn]

I have never been able to do that, I think the narrow beam of the Ss,Ds prevents that. You can mark it easily with the 200khz Sonar.

[Yam]

Any changes in water density are detected by sonar. Whether or not you can see these changes on your screen is another story.

A very pronounced thermocline is easily seen on downscan if you maintain a constant speed in still water. Of course, it's easier to see it on 2d especially with your sensitivity adjusted up. However, I have seen it on downscan. Keep in mind that deeper water will be even tougher to interpret because the cline is just a small fraction of the water column. The deeper the water, the smaller things are on your screen unless you zoom into a particular area.

In terms of a spring, I would think it's possible. Think about boat wash. This water has been disturbed by turbulence and is very pronounced on both side scan and down scan. Thus, I would assume that if a spring creates a fair amount of turbulence that creates steep density gradients, you should be able to see it on your screen. I would also think that if the spring temp is substantially different from the main water body, these sudden density changes could be seen on your screen as well.

[striperjohn]

What you will find is on ds the thermocline looks similar to a school of fry moving along. Thats why I don't like relying on it. Lowrance has a good tutorial on this as well as fishdoctor. I pay little attention to it on ds simply because your sonar 200khz shows it so much better and on ds it requires a great deal of interpretation. There have been pages of discussion on thermocline on past threads here with a great deal of information based on fishing experience not theory. You should look those up as they will help a great deal.

[21 Elite]

Thanks for the input from all have researched on line a little. Really haven't come to a conclusion as to what I was seeing. If I make it back this weekend I'll take a few pics and post. I know a picture is worth a thousand words. And would be interesting to see if anyone else has seen it.

[mwardncsu]

I can clearly see the thermocline when it exist with downscan and usually regular sonar.

There are times of year (colder months) after a big rain where you can see a submerged layer of muddy water as well.