Sonar and Double Echo

[CarlWBL]

Can anyone speak a bit about sonar and how to read the transition from soft to hard bottom? What I gather is that a double echo indicates that the bottom is soft, or sandy, and the bottom echo is where the hard rock lies. So when there isn't a double echo, the bottom is a hard bottom. Please let me know if I'm on the right track.

Thanks

Carl

[Deitz Dittrich]

When you are getting a double echo that is hard bottom. Soft bottom will usually only give you a single bottom reading.. HOWEVER, if you have your unit on auto mode, it often times will increase and or decrease the senistivity without letting you know, which can give you false readings.. also if you have it in auto mode, it will not have enough room at the bottom of the screen for a double echo.. when in auto mode I dont pay a ton of attention to double echos as many times they are false readings do to the auto settings.

[Ray Esboldt]

And it is one of those things that differs a bit from brand to brand and even model to model within a brand. You really need to find the correct manual setting to gain a level of assurance in what you are looking at. I can get a triple echo out of loose sand if I crank the gain high enough.

A short cut to fine tuning your unit, use it with an underwater camera some time. That way you know what you are looking at and how your unit interprets it.

[fishcast]

The way I heard is that the harder the bottom the stronger the signal it returns. Therefore more echos is generally a harder bottom. I have only used a flasher. If there are any echos they will be at twice or if you have an even harder bottom twice and three times the depth.

I use a flasher and its extremely obvious when botttom type is changing. I've been getting better reading the signals and can usually have an idea of whether its silt, sand, gravel, rock etc. I usually kind of guess at what it is then confirm what the change is with a bottom dragging presentation and feeling what it is.

[Ray Esboldt]

fishcast,

Yep. You are exactly right. More echos you get the harder the bottom content. However, if you turn the gain up high enough on a flasher or graph, you can create hard bottom looking returns where there is not any. I too am a flasher die hard. I can't fish without a flasher on the bow.

[CarlWBL]

Thanks for the help guys. For some reason I had my thoughts completely bassackwards. I do have an underwater camera and I think I'm going to take the suggestion to drop it down to view what I'm seeing on my graph. I think that will help a lot too. Frankly, I'm sick of using my graph as a depth only tool, and I think being proficient in sonar readings will help out my fishing a great deal.

I appreciate all the help.

Carl