# What am I looking at and where is it???



## Opsman (May 30, 2012)

Figured that title would get someone to look! I asked this question on another forum and really didn't get an answer so I will throw it out to you experts.
When I am drift fishing with my eagle depth/fish finder images, (whether fish or structure) appear at the right side of the screen and migrate towards the left.
My question, as I sit at the wheel of my boat drifting, where exactly are those objects in relationship to me? Say I want to anchor on that object Is it directly below? Off the stern or what?
Guy on another forum tried to tell me that you really couldn't pinpoint it, it just lets you know that it is in the area. I don't believe that.
Since my transducer is stern mounted as I drift am I seeing a conical area of water off the stern, reading from the port side to the starboard?


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## Bimmer (Aug 12, 2011)

This may help, explains better than I can.

http://www.hightechfishing.com/pdf/chart_tutorial_HIGHTECH FISHING.pdf


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## M.Magis (Apr 5, 2004)

The other guys are correct.


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## crappiedude (Mar 12, 2006)

M.Magis said:


> The other guys are correct.


I agree too.
Picture your transducer signal as an upside down ice cream cone. An object will appear on the screen no matter where it enters that cone. Usually though it only takes a few casts to locate an object once it's marked.


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## Opsman (May 30, 2012)

ok So in about ten feet of water I'm looking at about a 10ft circle of the lake. Fish that are shallow and close to the service will appear and disapear quickly, while I assume deeper object would remain on the screen longer because of the width of the cone?
Also, I understand that the transducer picks up the depth by looking straight down, no cone involved. 
I guess the only thing I'm trying to figure out is if there is a relationship as to where the object enters the screen? Does it necessarily mean It is something that I just drifted over, or could it be something approaching from the left or the right?
I understand what you are saying about figuring it out by making a few casts, but when you are drifting with live baits, you aren't really casting around that much.
Thanks,


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## M.Magis (Apr 5, 2004)

Opsman said:


> ok So in about ten feet of water I'm looking at about a 10ft circle of the lake. *Fish that are shallow and close to the service will appear and disapear quickly, while I assume deeper object would remain on the screen longer because of the width of the cone?
> *Also, I understand that the transducer picks up the depth by looking straight down, no cone involved.
> I guess the only thing I'm trying to figure out is if there is a relationship as to where the object enters the screen? Does it necessarily mean It is something that I just drifted over, or could it be something approaching from the left or the right?
> I understand what you are saying about figuring it out by making a few casts, but when you are drifting with live baits, you aren't really casting around that much.
> Thanks,


No, they would appear as smaller marks.

The marks simply show that something has entered the theoretical cone, and where at in the water column. How long it stays on the screen is just a setting with then unit.


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## crappiedude (Mar 12, 2006)

There really is no way to determine exactly where in the cone an object is located. 

Also keep in mind if the sonar shows an object at 10' deep it could only be 9'deep if its off to the side of the sonar or 10' deep if it's directly under the sonar. Imagine holding the end of a tape measure on the tranducer, now swing the tape and mark an arch at the 10' mark. An object that is located anywhere along that arch is 10' from the transducer will read as 10' deep.

I hope this helps.


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## crappiedude (Mar 12, 2006)

This link is a little long to read but it explains 2d sonar really well.

http://www.hightechfishing.com/pdf/proscorner_decifersonar.pdf


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## sherman51 (Apr 12, 2011)

one thing that might help. if your only in 10 ft of water your cone isnt going to be 10 ft wide at the bottom. the cone should be much smaller than 10 ft in only 10 ft of water. but this is just my opinion. so in 10 ft of water whatever your seeing is going to be very close to the back of your boat. now when your in say 50 ft of water the cone will be much larger at the bottom.
sherman


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## leeabu (Apr 10, 2004)

You also need to know the frequency of the transducer. Higher frequency = smaller cone. Some have two frequencies that is selected on the head unit.


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## Opsman (May 30, 2012)

Thanks for all the info guys


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