DI question

I know that the cone on DI is wide(side to side) but narrow front to back. The question is how do you tell if what is displayed on screen is directly under you or off to one side?

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Originally Posted by Sovran

I know that the cone on DI is wide(side to side) but narrow front to back. The question is how do you tell if what is displayed on screen is directly under you or off to one side?

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On a DI ... you pretty much don't. :Doh:

Best guess scenario is to know how wide a spread (angle) your DI beam is, according to whether you're using 455kHz or 800kHz, and understand that whatever is showing on your screen just went through the beam, somewhere.
800kHz = 45deg total angle .... @ 0.8 x water depth
455kHz = 75deg total angle .... @ 1.5 x water depth

I use 800kHz most all the time, and approximate that if I'm in 20ft of water ... then my DI beam is 16ft wide ... or 8ft wide to either side of the transducer. That's why I run 14' rods out in front of me, and shorter rods (8-10') out to the sides. That keeps most of my baits within the confines of the DI beam. I also know that whatever shows on the screen HAS TO be inside that beam, but I can only approximate its location within the width of it.

... cp :kewl

Thanks CP. I guess I was on the right track of tossing a weighted line out each side and dragging for the structure.

If your DI is on the TM, you can turn the motor 90 degrees if the object disappears you have it narrowed to 2 90 degree areas. If it stays visible on FF it is directly under TD.

Redge, go back to work. :biggrin

Also,u can use your 200khz (2d sonar)

If u have side imaging,u also could use that to reference the location

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Originally Posted by kosmo

Also,u can use your 200khz (2d sonar)

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How would that help indicate which side of the tdx the cover object is on ??

... cp :kewl

I think what kosmo is saying is that would help you determine if the cover is under the boat. HB 2d sonar cone at 200khz is only 1/3 depth of water at the bottom or only a 6.67 ft circle in 20 feet of water (3.335' each side of transducer). So if you where using 2d/DI you would at least know the cover is under the transducer or to one side. Is your FF a SI unit or a DI only unit?

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Originally Posted by rdjj71m

I think what kosmo is saying is that would help you determine if the cover is under the boat. HB 2d sonar cone at 200khz is only 1/3 depth of water at the bottom or only a 6.67 ft circle in 20 feet of water (3.335' each side of transducer). So if you where using 2d/DI you would at least know the cover is under the transducer or to one side. Is your FF a SI unit or a DI only unit?

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Your making my head work!