What You Don't Know About Traditional (2D) Sonar Is Hurting Your Fishing: How to use Fish Finders
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- čas přidán 23. 03. 2020
- This is episode 2 in our series of how to understand the technology and science behind sonars and fish finders. Be sure to subscribe and hit the notification bell so you will receive updates of new videos .
www.onecastfishing.com
In this video we are focusing on traditional, or 2D, sonar technology. This technology seems old school since we now have a lot of new tools to play with such as Down Imaging, Side Imaging, Livescope, Humminbird 360, and Livesight. However, traditional sonar provides us anglers a wealth of information that may not be seen on other scanning images.
Traditional sonar uses a radio wave, like all other sonars, to generate the image you see on your sonar display. This wave is emitted at an angle beneath the transducer, and the signal expands the further it travels in the water column. Therefore, the coverage area of traditional sonar looks like a cone, and is called the cone of coverage. The sonar sees less of an area near the transducer and a lot larger area on the bottom of the lake.
The lower the frequency you use on your traditional sonar, the large the coverage area. Most manufacturers, such as Garmin, Humminbird, Lowrance, and Ray Marine, use between 77-83 khz as their lower frequency on traditional sonar. Additionally, they typically emit this signal from the transducer at 60 degrees. If you know the beam angle and depth you are fishing you can use this formula to determine how wide across the coverage area is at the bottom of the lake. 2 x Depth x tan(Beam Angle/2). However, the rule of thumb for a 60 degree angle is the coverage area equals the depth you are fishing. Therefore, if you are fishing in 30 feet of water, the base of the sonar cone will be 30 feet across. That means an object right off the bottom on your sonar screen could be 15 feet away from the transducer in any direction.
Higher frequency traditional sonar is usually emitted at a smaller angler, typically around 20 degrees. The formula still applies but the rough estimate is your coverage area if you are using a 200 khz traditional sonar is your sonar sees 1/3 of your depth. So again, if you are fishing in 30 feet of water, then you sonar only sees a 10 foot wide circle on the bottom of the lake.
The benefits of using a lower frequency with traditional sonar is you can see a lot more of the water column. Fishing in shallow water this might be preferred. However, if you are fishing deeper then your sonar isn't as precise. Using the 30 feet example again, if you see a rock on the bottom in 30 feet of water with the 80 khz traditional sonar, that rock could be anywhere within a roughly 900 square foot circle. You will have to make a lot more casts to find that target.
With that said, you can see that higher frequency traditional 2D sonars are more precise since you don't see as much. Additionally, higher frequency sonars allow for more target separation on your screen and you can see more detail.
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You can run both sonars at the same time. This can help unlock the advantages of both. If you see an object on the lower frequency but not the higher then you know that object is between the two cones of coverage. You can regraph the area until you see the object on both sonars. When that happens you know that that object is pretty close to that transducer.
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Fish arches are created when a fish enters the cone of coverage. At this point the fish is the furthers away from the transducer. As the fish swims through the cone that radio wave has less distance to travel back to the transducer to that fish appears to rise slightly on your screen. As the fish exits the cone of coverage it is again the furthest away from the transducer. - Sport
There are alot of good explainer videos out there. Having written that, you are the FIRST guy to explain why a fish creates an arch.
Well done!
Thank you very much. Try our best
This was really informative. I was having issues determining where the fish were on my Striker 4. This will be a huge help. Thanks
Thanks, great tips. Your explanation of why fish display as an arch was a revelation. Makes perfect sense. Just never heard it explained like that!
Man this is some straight matrix loading input in my head! Good video!!
this is what I needed, i was confused, but now it makes sense. Thanks for your time and making this
Straight forward,excellent information and well explained, many Thanks
Golden information! Thanks so much!!! Very clear explanation!!
Won't find a better video on explaining great job!!
Really well done video. One of the best I’ve seen on the basics. Thanks.
Thank you. Thanks for watching and glad you got something out of it.
Best explanation on youtube, Thank You !!
finally a good video that explains it well. thanks man
Thanks man, this is the stuff I have been missing out on.
good to see someone making the formulas easy to understand
Appreciate that. Thanks for watching. I’m finally dropping my side imaging video tomorrow
this is a fantastic video! I might even use this while im teaching high school and the practical applications of basic math/geometry and wave-frequencies!
This might be one of the best comments I have gotten! Thank you
Make a vid if you can to show before and after correct installed transducer, it will help a lot of folks! Cheers for a good vid!
Great info, easy to understand keep it coming
Thanks for watching. I’ll be posting another sonar video next week about down imaging
Dude you are fantastic at explaining 👍
Great video. Thanks
Great explanation, thanks brother!
Glad you found it useful
Last couple minutes are easily the most useful! Being able to do those quick calculations in your head sounds like the best way to unlock the true potential of fish finders
Can you address how best to utilize a trolling motor mounted unit/transducer? My bow mount unit and console unit seem to convey different information.
great video. I'm going to use the higher frequency for ice fishing where I'm fishing vertical, right below the hole. don't need to know what's going to far away because I fish dark/ stained water.
That would make a lot of sense. I’m glad you found something useful out of the video
Really well done thanks yes I need the "ping speed vs High CHIRP" and all that work together ? yes im totally confused LOL
I am wanting to use one of these for fishing my Traxxas Xmax off the bottom of the lake.Will it locate a 20lb 3 foot by 2 foot rc car?
Can you get both frequency on a lcx 28c hd
This was an EXCELLENT video. Thx for explaining the math behind it. So let's say the ping is at 150khz...roughly halfway between your examples frequencies...would the cone diameter be roughly in the middle of 1x (80khz) and 1/3x (200khz) the depth...2/3 the depth?
It's logarithmic.
What does the sonar show as the depth? Since it gets returns from a large cone, is there some inaccuracies potentially if it is reading the far side of the cone, or can it always read the shortest distance somehow, thereby giving an accurate depth? Also, would be nice if they would represent the cone widths at various depth, but I guess with 2d screens it gets difficult to represent.
My man. I have the same question. I literally cannot find the answer. Like what if the cone is straddling a drop off, the cone has 100 feet depth on the left, and 500 foot abrupt drop off on the right. What is the depth reading? Average? What shows on the sonar screen??
Sonar uses "Radio" waves?
Nice explanation! Thank you for taking the time to make this video. Now the kicker is how to know where or when to cast when that fish comes across the fish finder. I’ll look to see if you made a video of this. Not sure how to use the “waypoint” you was talking about. I’m trying to find a good fish finder but it’s been very difficult to find the right combination of sonar angles(transducer). It seems a lot of the finders I’m finding are 200khz plus even 400! What is a good fish finder model for a kayak or one in general? I fish in SC lakes and I would love to try fish intercoastal waters.
Kali, that is the hard part. If you are only using traditional sonar that fish could be anywhere in the cone. If you have a graph that can run both down imaging and side imaging it can help you narrow down where you need to cast since the down imaging is only looking down and to the left and right of transducer. As for good fish finders. I run Garmins and Humminbirds. Humminbirds have a little better picture but the Garmins are more user friendly, typically a little cheaper, and you can adjust the traditional sonar cone more.
OneCast Fishing thanks. I know I ask some difficult questions haha but you’ve answered them well. So what do you mean by adjust the traditional sonar more? So you’re saying it’s good to have low frequency, high frequency, side imagine and down imagine? It’s hard to do that on a 4 inch screen. What’s a good Garmin I can research and read up on?
No worries! I’m glad to help. On my garmin, though I do have the 126sv echomap ultra, I can go into sonar settings and adjust the frequency and beam angle. On my old garmin I could adjust the frequency but based on that and the owners manual I could determine the beam angle and coverage area. Ideally you want to run traditional, down imaging, and side imaging all at once, but that almost impossible to do on a 4 inch screen. You won’t see much. In that case I would only use traditional and down imaging and maybe only one at a time. If you’re looking for a garmin look at the echomap series. Garmin just introduced the new version so you can get the slightly older ones for some really good prices right now. Those would be the Echomap 93sv or the Echomap73sv. Both of those are outstanding units.
OneCast Fishing so I just looked them up. Amazing units. Very nice and also a little pricey. I see the 93 is touch screen. I assume the 73 is too?! So question on down imaging....what is that dark line in center...I think it’s called water column? Do you actually see fish on the down imaging? I really like these units. I’ve been finding the UHD and PLUS. Not sure what the differences are? Sorry for all the questions and thank you for your patience and help.
OneCast Fishing so I just looked them up. Amazing units. Very nice and also a little pricey. I see the 93 is touch screen. I assume the 73 is too?! So question on down imaging....what is that dark line in center...I think it’s called water column? Do you actually see fish on the down imaging? I really like these units. I’ve been finding the UHD and PLUS. Not sure what the differences are? How do the echomap differ from the striker models? And some say echomap 74cv instead of 73sv. Sorry for all the questions and thank you for your patience and help.
How does the cone read 2 fish swimming side by side at the same depth? Would only 1 arc show on the screen?
Potentially. Depends on size of fish, how far apart they are. It could look like a blob too, kinda like when multiple baitfish or perch are grouped up together.
I did find you'd video till today 2023 July.
Could you send me the name of a brand and model of two of the best fish finder/sonder that reach deph of 800 feed and still give me clearly good image.
So it must have A very low fequency.
Hope to hear from you soon
what mic are you using
Rhode wireless
@@OneCastFishing Thank you
Hello, thank you for the video. I just don't understand the math formula to calculate the sonar scanning area, could you please help me???
Area of a circle is Pi*r^2, so 3.14*(5*5) is about 78 square feet under a circle 10 feet in diameter.
The sonar doesn't use radio waves. It uses sound waves.
Right, that threw me off too….radar uses radio waves….not sonar
Not radio waves, “son-“ :sound waves.
Technically it is radio waves based on the electromagnetic spectrum
@@boyankartolov5342 Technically it is NOT the same. There is nothing electromagnetic about sonar. Sonar is purely a mechanical process. Radio is electromagnetic. Think lightning & thunder.
@@richardfs7814exactly….just like you can’t hear anything in space (not enough molecules/atoms to transmit sound) but electromagnetic waves can propagate fine
All you saying and explaining is depending on that the transducer is level with the surface when the boat is for example in idle-speed, otherwise you may not see 1 arch and think WTF is wrong with the stupid sonar..
Thanks. Yeah you’ve got to get it level. When you install it yourself that becomes the biggest pain.
Dude it’s using sound waves…..not radio waves. ….radar uses radio waves
When an engineer takes on fishing as a hobby….
1 guy still doesn’t know how to use sonar