I get asked many times about which is better. To me Down Imaging with it's limited coverage area is less attractive than Side Imaging...One reason: Coverage Area. And most importantly Coverage Area away from the boat.

Down Imaging has benefits and is a great step to transition from Traditional 2D Sonar to High Frequency Sonar but both 2D Sonar and Down Imaging lack the coverage area of Side Imaging.

2D - 200kHz Sonar is 20 Degrees or 1/3 of Depth
2D - 83kHz Sonar is 60 Degrees of about equal to Depth

DI has different coverage. DI from SI has three user adjustable widths: Narrow, Medium and Wide.

Narrow is close to the 200kHz or 1/3 of Depth
Medium is close to the 83kHz or Equal to Depth
Wide is wider than both and close to 1.5 times the Depth.

In Down Imaging/2D models the coverage area varies by frequency:
800kHz is approximately equal to Depth
455kHz is approximately 1.5 times the Depth.

With Side Imaging the user selects the amount of Area of Coverage in the Menu. So you can view how much bottom and to the side coverage out to 240' to each side for a total of 480' of coverage...no matter the depth. This is the power of Side Imaging.

Here are a couple examples of the exact same structure showing the additional data that DI does not provide.

Down Imaging:



Side Imaging:



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But Can DI tell you Direction? Just like 2D sonar you cannot tell which side of the transducer the data came from...



But Side Imaging I can tell which side of the transducer the data comes from...



This image is marked up to show where SI shows the blocks versus DI that has no ability to tell which side



Hope this helps understand the features and advantages and the differences.

Excellent information for a 58 year old rookie fish finder user. Currently saving for an 898 and have been getting great tips on settings and what to look for are what objects look like from your post.
Thanks

This is excellent information, especially the information about the information about the depth and relationship to depth. I learned something. Thank you.

Ron

I was questioned on another forum about the first images and where the data was in the Down Imaging compared to the Side Imaging so I marked them to show reference and the added coverage you get to the sides with side imaging. Hope it helps...

As always, you da man

My HB 1197 was instrumental in our championship win on Sam Rayburn.

Interview with Champions

Awesome Clip! And an Awesome Win! Amazing what can happen when you believe in the Technology!

Thanks Doug

Good stuff Doug

Doug, thanks for the pics, awesome stuff. I have a rookie question ,
With the Down Imaging I can see the ditch or creek with the fallen tree in it but with the Side imaging I can not tell that there is a ditch or creek in the pic. I can only see the fallen tree. How do you determine that it is a ditch or creek?

Thanks ,
Laine

Look at the Width of the water column that tells the depth real quick. When it's wider it's deeper narrower it's shallower.

kevinLL, this is a more pronounced creek channel with Side Imaging where you can see the depth change better:

ok , thanks Wayne.
Now I see it. great info. guys.

This video may help you too better understand the views: http://youtu.be/3xe6pLPdMKc

Would side imaging perform well on a kayak?

If you can minimize rocking side-to-side when paddling, yes it works great at very slow speeds with the right settings.
I regularly use SI at below 1 mph.
I was looking for shad schools in a creek channel using the trolling motor mounted setup in this screen shot--note GPS speed