Time for this old redneck to upgrade. Ive been looking at the Humminbird Helix models. Really interested in Helix 10. Noticed that some models have SI and the other DI ? What does this stand for ? The days of lining up towers and trees are over with - Any feedback on your preferences is appreciated. Like all things ,, I know there are pros and cons. Thanks, Rio

There are two types of sonar in recent history. The one that is like the "old days" is called 2D sonar and broadcasts a somewhat inverted cone shaped sound pulse.
The new kid on the block is Imaging. That has a very thin sound pulse front to back and wide to the sides sort of like a CAT scan that hospitals use. That thin pulse produces a somewhat picture like image if what is below.

Side Imaging has two sonar pulses, one broadcasts to the left and the other broadcasts to the right. That will produce what looks like this rock pile with lots of crappie around:



Down Imaging is more downward focused but is still Imaging and looks like this tree on the bottom:



This screen shot shows the difference between how 2D sonar and Down Imaging represents a brush pile:



Humminbird has Sonar models that are 2D sonar, DI models that have Down Imaging and 2D sonar, and SI models that have Side Imaging, Down Imaging and 2D sonar.
In the Helix 10 series, all of them have GPS/Mapping.
The version you choose includes a transducer that will produce the sonar technology/s that the unit is capable of.

Those images are what you can expect from a 10.
SI is a great tool at both the console and the bow.
This last weekend we were marking brush piles and rock piles. We would see them on side imaging then move the cursor over the object and press the "Mark" button to create a waypoint we can reference on the map.
With SI on the bow I can find it again then keep it with in casting range without having to troll over it to find it.
You will want one of the map chips. Make a list for f what lakes you fish most and see which map has high def maps of your lake. Lakemaster HD maps are great and there are extra features you can use with them. Navionics HD maps are good too but they don't have all of the Humminbird features the Lakemaster has.

The Helix 10 will have better images than those screenshots since it has a higher pixel density display. Those were with a 1198c SI Combo.

Thanks Wayne P. and Rickmb - Lots of good info. As you posted, I was told that the Helix 10 has higher pixel density display. Still learning about the maps ?? Rick mentioned the Lakemaster HD maps ? ?

Essentially two brands of map chips available. The Helix does come with some built in maps but they are nothing compared to Navionics or Lakemaster. Both offer great products however Lakemaster has additional feature on HBs. They allow you to adjust the lake map based on whether the lake is high or low and redraw the map and depths. Very important when running a place like Amistad or Canyon where ledges and rocks piles submerged at full pool are just waiting to grab you when the lake is low. This feature is not available on Navionics on HB. The Navionics mobile app does have this feature and I recommend it for your phone or tablet.

Lakemaster also has a highlighted range feature. You pick a depth and how many feet +/- and it will highlight that range in green all over the lake. Also by looking at the width of the green band you can easily spot flats, points, and drop offs.

Make a list of the lakes you fish most. See if they are on the Lakemaster list. Lakes that are HD have actually been scanned by Lakemaster and will be recent and accurate. Combined with the water level offset feature and highlighted range they are the best for lakes they cover with HD.
Navionics HD maps are excellent too. To account for small water level adjustments you can adjust the shaded depth. I usually highlight 3ft as my safety margin. If the lake is 2ft low I make the shaded depth 5ft. Anything over 10 ft gets difficult to see and the depth markers don't change.
I carry both chips just to make I'm covered. Some of my favorite lakes are not covered by Lakemaster but Navionics has excellent maps of them. Since they are constant level the water level offset isn't a factor.

The Helix 10 has over 5,500 more pixels per square inch than the 1100 series.

Great info, thanks!