choosing sonar

[tugboat80]

New to fishing, I like gadgets and have aquired a limited run of a down imaging unit. On further reading I find that it has limited choices of frequency, all high, no lower freqs for deep use, no dual cone application. Is this bad for fresh water? Is down imaging just for seeing bottom? I wanna see fish. Thing of trading it back.

 

[dingbat]

Re: choosing sonar

A lot of people bought into down imaging as a better fish finder w/o looking into the details. Now they are coming to realize that DI is good for taking picture of things on the bottom but has limited use when actually fishing. Not to mention they don't work well or at all in rough water. The high frequencies used to generate the "picture" are very sensitive to movement and you end up with nothing but a blur on the screen when it’s rough.

If you want to wow your friends with pictures of objects on the bottom get a DI machine. If you want to impress them with your catch, get a conventional sonar unit. If you want the best of both worlds, buy a conventional unit that you can add blackbox DI to it.

 

[mommicked]

Re: choosing sonar

I'm no expert but it seems to me you would need fairly deep water to get images of structure w DI?

 

[tugboat80]

Re: choosing sonar

Thanks for the experienced opinion, I was thinking the two technologies may not be best from the same box. It seem in my unit the di uses higher frequencies than the older sonar and the sonar side gives narrower beams 16/25 degs and less depth due to the higer freqs. I am thinking of "down grading" to a pre di box of 300 watts 0f 20/60 degrees.

 

[John_S]

Re: choosing sonar

DI gives a detailed view of the bottom using a higher freq narrow beam. It is not good at finding fish. Fish will show as small objects to relative scale. Higher frequencies get absorbed by the environment, more so than lower freq. DI doe not have the range of "normal" sonar.

Since you used HB terms (DI) vs DS, what model is this? As far as I know, all HB had 200kHz sonar as well. Use that for fish finding. Set the switchfire option to max, and increase sensitivity if you are not picking up fish. The HB DI units do not have the 83KHz beam. While mine has that capability, I turn it off. It slows the display speed down.

How deep are you try to spot fish?

 

[tugboat80]

Re: choosing sonar

Thanks, Admiral, for the learned advice. The unit was a 587ci hd di. 300 watts. I traded it recently for a 597 hd gps "normal" 500 watt unit with 20/60 degree cones 83/200 mhz. The other unit I could not get good effect from the di for either lack of experience or whatever. I hope to learn more from the wider cones and see more distinct arches. My depths will range from two feet to two hundred or beyond, if practical in north Idaho lakes.

 

[John_S]

Re: choosing sonar

Yea, no arches in DI. Set switchfire to max, if you like arches. Expierment with the 83khz. If it provides info you can use, leave it on for deeper waters. If not, I think you will see a display update improvement if you turn it off.