How to read a fish finder?

[rob123p]

Ok, here's my question and I do apologize in advance if it is a stupid one. How do you read a fish finder? So... the transducer is on the transom so the cone of the radar reads whats behind your boat. That I get. But the image on your screen keeps moving although your boat is still. How can the sonar read ahead of your boat if you are not moving. Am I totally off on this one? If it is showing a fish at 8 feet it looks like the fish is moving. So is the fish still there, and the same goes for structure. Have you passed over it or it is still under your boat if you are not moving? The answer to that should be obvious. Anyways it seems hard for me to read the screen when my boat is still but the image just keeps moving.

Any advice is highly appreciated

 

[fhhuber]

The fish finder is scrolling in time, not distance.

The complete answer will depend on the fish finder...

But pretty much any fish finder under $300. Scrolling in time is all you need.

 

[Chris1956]

As was said, fish finders scroll in time, although it appears to be motion. So, if you were to remain motionless over a structure (hard to do unless anchored bow and stern), that structure should stay on the screen. Fish swimming thru the sonar cone, would move in the same direction, regardless of their real direction.

The sonar cone gets wider as the water deepens, but is a vertical cone under the transducer, on most models. Some high end sonars can project forward.

Sonars tend to refresh at the same rate, so their readings are distorted a high speed boat. Some sonars do not read well at high speed. This can be caused by bubbles near the transducer, and possibly by sonar design.

 

[rob123p]

Ok so if the sonar moves through time, again the same question if 10 seconds have passed and it doesn't show the fish does that mean the fish has moved away. I am working with a Lowrance Hook 7 with CHIRP

 

[dingbat]

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[dingbat]

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[airshot]

Keep in mind the cone is not a very big diameter. On my unit the cone is approx. 1/3 the depth so in 20 ft of water the cone is 6+ feet in diameter at the bottom! Now come up 5' from the bottom and the cone is probably only 4' in diameter so you are not seeing much area. As it scrolls across the screen, consider individual pictures that keep flashing every couple seconds. That scrolling is a number of pictures showing where that fish is in that small dia with every new flash. The fish will not stay in that cone for very long! Not sure if this helps or not...but yes they do take some practice on reading them with any degree of accuracy. The less expensive they are the more difficult they are to read.

 

[ondarvr]

The leading edge of the screen shows real time, the rest of it is history. You can set it so it shows only real time, but that can be confusing, hard to read, and you must look at it 100% of the time to know what's going on. There are applications where this works well though..

 

[Teamster]

Some good free stuff on sonar here,......

 

[Teamster]

And here as well,...

 

[82rude]

Most mfg of depth finders have a tutorial section that can be helpful in learning about your unit.Personally I never use mine as a fish finder.Just depth and structure .Ive caught more fish when its showing nothing as compared to the other way around most likely as explained by airshot.Of course where you fish,how you fish could change the story completely.

 

[Silvertip]

Consider "time" and "scrolling" as someone painting a picture of the sonar image at any moment in time. Then one second later a new image appears, and one second later another and another and so on. The image at the side of the screen needs to get out of the way for the next image. Remember, this is not a camera. The electronics in the locator has to receive the sonar data, assemble the picture, display it and then work on the next frame or image.

 

[rob123p]

Very useful info guys. Thanks a lot, I'm beginning to understand more about sonar. And of course as the boating season starts practice practice practice. Here's another one, so I have a good lowrance piece with Navionics and CHIRP sonar about 7 display, I have a second fish finder that is not so good, it's pretty much a portable. Which one would you guys use at the trolling motor, the piece with the maps and all or the portable?

 

[airshot]

Most mfg of depth finders have a tutorial section that can be helpful in learning about your unit.Personally I never use mine as a fish finder.Just depth and structure .Ive caught more fish when its showing nothing as compared to the other way around most likely as explained by airshot.Of course where you fish,how you fish could change the story completely.

I have the same situation with catching fish when nothing shows on the screen, just to embarrassed to mention it here. There are times when the screen is full of fish and we catch nothing as well. Like you said it is a tool for marking bottom structure and depth primarily.

 

[Silvertip]

Folks need to understand that everything that shows up on the screen as a fish symbol is not a fish. It may be debris. A screen that shows almost black with fish symbols likely has the sensitivity set too high. Catching fish when none are shown means the sensitivity is set too low. One setting is not best for all depths and water conditions. You need to tune as you go. I want the best locator up front because that's where I'm fishing from. I also set the locator so I'm looking at fish "arches" rather than symbols. Before you even get on the water you should research the body of water so you don't waste time fishing in spots where there likely are no fish. You then don't need to drive around looking at the locator -- except to identify structure where fish are likely to be. Then use the bow locator to stay on that structure. In fact if you do that you really could care less if the locator shows fish or not. They are either there or they are not. If a few casts don't produce you move around.

 

[82rude]

rob 123p I just bought a new fish finder yesterday .Nothing fancy ,garmin spark4 ? so I will be in the same boat as you (no pun intended).Has chirp,gps and a bunch of other stuff also and is 4 times cheaper than the piece of junk I use now.Boy have they come a long way from the 90,s .At least now I will see fish I don't catch in color,lol.

 

[redneck joe]

least now I will see fish I don't catch in color,lol.

Now thats funny.....

 

[82rude]

edit striker4 not spark 4.

 

[dwco5051]

Very useful info guys. Thanks a lot, I'm beginning to understand more about sonar. And of course as the boating season starts practice practice practice. Here's another one, so I have a good lowrance piece with Navionics and CHIRP sonar about 7 display, I have a second fish finder that is not so good, it's pretty much a portable. Which one would you guys use at the trolling motor, the piece with the maps and all or the portable?

I would mount the old one on the trolling motor or the front. In my case I fish on the same lake most of the time and have been fishing it for fifty years now. Since it is only 1700 acres I know it pretty well. I basically only use the front fishfinder when I am working along the edges of the old stream beds, stone walls that used to be on farm field edges, drop offs, and other structure. That way I know exactly where I am and where to cast. Most of the time I don?t even turn on the one at the console. The exception is when I am fishing with my 11 year old granddaughter and I use it as a teaching tool. I leave it on when fishing as she can see it from the rear pedestal seat and she can see pretty much what I am seeing except that transducer is 20? farther back.

In your case I think the same would apply. Keep the new one on at the helm for general navigation purpose to find the spot you want to fish and keep you from running aground and use the one by the trolling motor while actually fishing.

 

[rob123p]

I'm thinking of using my phone since I have Navionics on it already to navigate the lake and the old fish finder on the console. This way I can see the lake and also check for changes in depth on my crappy fish finder. Put the nice CHIRP on the trolling motor that way when I'm ready to stop and work an area I can focus from the front of the boat.