Down Imaging only units

Does anyone know if these units are very good for finding cover/structure? Not sure how wide the sonar beam at certain depths. Seems you would have to be fairly deep to show a fairly wide area.I am torn between one of these or a much more expensive side imaging. any thoughts?:rolleyes:

Dray81,
I am assuming (uh-oh) that you are meaning the Lowrance brand Down Imaging units here as the Humminbird DI units also have 2D sonar which would make it easier to find structure. I could provide you with numbers to figure the sonar area of coverage for the Humminbird units if you want it.

I have both and much prefer the humminbird. I have a 798, had a 997 and have a 1197. Of course bigger is always better but for the money the 898 is a great deal.

If you need 2d to make it easier then Down Scan to find structure, I'd recommend you buy the cheapest 2d unit possible, from any brand. The benefit of down scan or down imaging is that you see what's under the water, clearly. You don't have blobs like 2d provides.

Here's 2d and down scan side by side, tell me which is easier to find structure on?
http://i45.tinypic.com/2n1t3s6.jpg

Greg,

I have a new 596C HD DI, and would be interested in the beam width at different depths. I haven't had it on the water yet, waiting on trolling motor bracket.
Thanks,

bigminner

You are right mduncan. I was thinking about fishing the structure without being stationary over it and not finding it to begin with. DI sonar will make it easier to find the structure and far easier to see what it really is all due to the very wide (side-to-side) but narrow (front-to-rear) sonar beams. Our widest DI beam is over four times wider than a 20 degree 2D sonar beam, so you can see how that would allow you to cover more water faster.

As for seeing fish though I think that the 2D would be better due to the way it would display them.

bigminner,
I must have been typing when you made your reply. Here is what you are looking for:

2D (conventional) sonar:
16 degrees at 455kHz, area covered = 0.28 X water depth
25 degrees at 200kHz, area covered = 0.44 X water depth

DI sonar:
45 degrees at 800kHz, area covered = 0.83 X water depth
75 degrees at 455kHz, area covered = 1.53 X water depth

Thanks,
that is good info to know.

bigminner

Thanks for the info. If the HB has both 2D and Down Imaging I will definately go with HB. looks like there is greater coverage also with DI than the 2D sonar? Just seems that the DI would have greater value the deeper you are and SI may outshine it in shallow water.I f you are in 6 ft of water and the DI only shows what is under you, you have probably spooked any fish that may have been directly under you.Gona get one, that way I will know where the trash piles are and where fish SHOULD be... By the way I called HB customer service last week and was talking to a live human being within 5 minutes.

Quote:

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Originally Posted by Humminbird_Greg

bigminner,
I must have been typing when you made your reply. Here is what you are looking for:

2D (conventional) sonar:
16 degrees at 455kHz, area covered = 0.28 X water depth
25 degrees at 200kHz, area covered = 0.44 X water depth

DI sonar:
45 degrees at 800kHz, area covered = 0.83 X water depth
75 degrees at 455kHz, area covered = 1.53 X water depth

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Greg, I know here Understanding Side Imaging - From HB Manual there are acual visual pictures diagrams of the 455 and 800 beams for the SI sonar beams....

Do you know if customers have access to a similar diagram for the new DI units degree of coverage...??

A diagram might make it more easily understood for people to wrap their head around what the shape (and width) of the DI sonar beam is...

I'm not good enough in Paint to draw this myself...

Rickie