Fish Finder Training – Screenshots & Interpretations

[J-Doc]

You are correct. The 455khz signal is better for shallow AND......downscan also requires the boat to be moving a little to get the best picture. At least .7-1mph I believe. I forget the exact number.

It amazes me how much stronger and clearer the sonar screen is on the Gen2 HDS models vs. a standard "sonar only" model. That's probably because the HDS units have more power (more watts of power, much like an amplifier) and you also have the module that the units connect to which also cleans up the signals I believe.

I have a small Lowrance color graph on the bow and it's nothing like your screen shots. Yours look WAY better. Same transducer, just more power and better quality unit. You DO get what you pay for.

[Bass Ivy]

I read through this thread and I didnt recall seeing in Down Scan images beside a sonar image so I thought it might be helpful to some folks. To add some screen shots. I had some really good shots from Avoca Hollow of some timber and structure and fish but I lost them i guess. Im no pro at operating these units but Ive had Lowrances or Eagles since 1996. I figured I was ready to try out a decent unit. I have a Eagle Fishmark 320 on the bow of my boat and I can set right on top of fish with it and watch my bait and see fish come up and hit my bait right on the screen. Ive had that Fishmark 320 for a long time. They are a pretty good cheaper unit. I need to mount my 8 on a ram mount so I can see it up front. Or get me a smaller gen 1 lowrance and put up front. I can network another Lowrance up front and it will show the same view as the unit in the rear, but I want the transducer right underneath me. I like to fish for bass, crappie, whites, and I catfish too, but I also fish for stripers. It takes a unit up front and one at the console to do all that. The only fish I troll for is stripers. I got a smaller boat, but I will troll 10 to 12 lines at once. Run 6 planer boards 3 out each side and 2 down lines and 3 or 4 balloons out the back.

[J-Doc]

I may be throwing people off by using a white background. Yep, there are some downscans in there that I've posted previously.

I have an Elite 5dsi (Gen 1 unit, not HDS) and it's using 455/800khz but I use the "white background setting" because with sun glare on a small screen and my failing eyes, it's easier to spot fish with color on a white background vs. a black background and a tan, red, green, or orange "blip" on the screen.

Here's a down scan image from mine where I break down what you're seeing. (white background)

Here's one with the factory "sepia" background and before I knew I could do screenshots thru the unit!

And one of my favorites using color. To me, this is clearly a school of crappie on a tree (in Esculapia Hollow)

Feathers and Fins uses a white or offwhite background on his HDS8 unit and it works well.

Thanks again for sharing your screenshots and your interpretations. THAT is what this thread is about!

[J-Doc]

After looking at yours and comparing to mine..........

You can clearly see the level of detail that HDS units have over the lower-cost Elite units.

[zarraspook]

Just before the 16lb striper hit..

[J-Doc]

Here is an interpretive image below to help explain what we are seeing in zaraspook's image above.

To understand this, you truly need to know the fundamental differences between traditional low frequency sonar, structure scan (hi frequency sonar) and side imaging (or side scan) which is hi frequency sonar looking outwards at an angle away from the boat. There are lots of quick Youtube videos on this. Also the link I shared above provides some breakdown on screenshots and understanding what you are looking at.

Here is an image where I have provided a rough interpretation.

[J-Doc]

Here is an extremely helpful article explaining critical sonar concepts.

You can skim over it or read all of it. You will learn something either way.

http://doctorsonar.com/blogs/educational-articles/12380345-lowrance-pros-corner-by-luke-morris

[John Hopkins]

Thanks for this. I'm debating if I need a single or dual beam Humminbird for my kayak. I have availability to both either a Pirhanamax 143 or a 153, only a $10 difference between the two. I'm leaning toward the 153, just because they're getting hard to find.

[J-Doc]

I assume you will be shallow most of the time using a kayak. So dual beam really won't make a difference for you. Dual beam is best for deeper water applications

[J-Doc]

Here is a good image showing the difference in cone angles between downscan and structure scan. Traditional sonar uses a circular cone angle to dispearse the sonar signal in a sound wave. Structure scan uses an oval shape to dispearse the sound wave.

Think off the cone angle as a flashlight beam......if the fish is inside the light, you can see it. If it's outside the line (cone angle), you can't see the fish.

Hope this explains things better and makes it easier to understand.