Hummingbird's Side Imaging Technology
June 20, 2008
In 2004, Humminbird introduced the Side Imaging feature in their 987SI unit that forever changed the electronic fishing instrument industry as we know it. Side Imagining is the newest craze and it is the biggest phenomenon since we graduated from the flasher units to the pixel sonar back in the 70’s.
Humminbird's side imaging was first incorporated in their 987SI unit in 2004, and then in early 2007 it was replaced with the upgraded 997SI. There are currently only two Humminbird units that feature the Side Imaging Technology. The largest and most powerful unit is the 997SI and the smaller more compact unit that features the side imaging technology is the 797C2. The 997SI has a full size 8 inch diagonal screen while the 797C2 SI has a 5 inch diagonal screen. More specific specifications and information on these units can be viewed at www.humminbird.com. Video details on how the Side Imaging works can be viewed at www.sideimaging.com.
Side Imaging vs. Traditional Sonar
Side Imaging provides picture-like images of the bottom, structure and fish, covers an enormous area at one time, and offers the following advantages over a traditional sonar unit that does not have the side imaging technology:
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A picture-like view of the bottom to both the left and right sides of the boat
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Up to 480 feet of side-to-side bottom coverage at one time (saves time)
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Total 180° coverage for spotting bait and fish in open water
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Ability to pinpoint the location of fish, cover and structure below, to the left or right of the boat
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Ability to mark the GPS location with incredible accuracy of structure up to 240ft on either side of the boat without actually running over the structure with your boat (hence scaring the fish off the structure)
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Split screen viewing options to show traditional down-looking and Side Imaging sonar simultaneously.
At first, the side imaging part of the unit takes some time to get used to and to interpret. With traditional sonar your information goes from right to left. But with the side imaging the information goes from top to bottom. The information at the top is the most recent data and the information at the bottom is your oldest data. Having the information displayed like this makes it easier, as anything that you see to the right of the boat is displayed on the right of the screen and everything on the left is displayed on the left. You know exactly where to direct your boat for whatever you are trying to find i.e. structure, brush, fish, etc.
Side Imaging Advantage
In my two years of experience with Side Imaging Technology I have found countless advantages in terms of fishing applications and how they can help you become a better and more efficient angler.
As a pre-fishing tool, Side Imaging lets you cover more area in less time. Since Side Imaging lets you cover up to 240 feet on either side of the boat it is a HUGE time saving feature, especially if you are a tournament angler under time constraints. With traditional sonar you will need to zigzag for hours on end to get a firm grasp of what is under the water.
The Side Imaging lets you see to both the left and right simultaneously, so when you spot structure you’ll know which side of the boat it’s on. Now you can cast towards the structure, or if it’s further out just use the sonar cursor to mark the structure’s location and motor to it using GPS coordinates.
I have found that once I have spotted bottom structure on Side Imaging, I have a better understanding of its orientation on the bottom so I can develop the best strategy to fish it. Traditional sonar is only one dimensional, but Side Imaging offers a “top down” topographic style presentation that virtually maps how the structure lies on the bottom. Often times I use the sonar cursor and mark capability to save the GPS location of both ends of a sunken tree on the bottom, then just fish between those two marks. This enables me to fish the tree at a 90 degree angle or parallel by looking at my two GPS points located at either end of the sunken tree or cover.
Side Imaging provides a great picture of bottom hardness – hard bottoms, especially rocks, provide a stronger return and typically appear as lighter shades than the surrounding softer bottom. This makes it very easy to find road beds that don’t have any contour change on either side but they do have a harder bottom.
One of the coolest features of the 997SI unit aside from the Side Imaging is the ability to mark waypoints up to 240 feet off the side of the boat. You can mark bait, cover and structure off the side of the boat WITHOUT actually disturbing the area with your outboard. This allows you to ease in on the area and fish it undetected.
One last feature that I enjoy with the 997SI unit is the ability to take pictures or recordings for uploading onto your computer. The pictures are great training tools to teach anglers how to read what they are seeing on their unit and to help them gain more confidence in what their unit is showing them.
Actual Side Imaging Pictures
It is very difficult to write an article about side imaging without actually submitting some pictures to show the reader what the Side Imaging can. There are literally thousands of examples of pictures that I can show that are unique to the Side Imaging Technology. Below are a few pictures with some information to help describe what the image shows (*click on pics for larger views).
This image is of an old iron bridge that was left in place when they flooded this lake back in the 50’s. In the picture you can clearly see the bulk heads which are made of rip rap type rocks the bridge sets on. You can also clearly tell where the channel is where the bridge 
actually spans across. The shadows that are emitted from the iron beams also show up on the lake bottom give you an idea of the height of these beams as well as their thickness. The interesting thing about this bridge is that it doesn’t show up very well on any sonar that I have seen. So the side imaging really gives a clear image of how everything is laid out.
Let’s say you find a small meandering ditch on your sonar like the one pictured above. It would take you many passes to find the steepest part of this ditch. The fish can be ANYWHERE in this long ditch. More than likely they are going to be on the steepest break within the ditch and more power to you if there is cover on this ditch (which there is not in
this picture).
With the SI you can find and mark the steepest part of the ditch in only one pass over the area AND mark it with your GPS cursor (see cursor in photo) up to 360 feet to the side of the boat without ever going directly over the ditch itself. You prevent spooking the fish so you can fish it instantly especially if your unit on the front of your boat is communicating with your unit at the console - when you put the trolling motor down you can pull up your map and make your way toward the GPS waypoint you just made. In this picture my cursor is approximately 52.4 feet off the right side of the boat (See insert at top of picture for this information)
Just to the right of my cursor you can see the shadow that the lip of the ditch is casting. This represents height or steep drop off in this instance. It is the same thing that if you took a flashlight and shined it at your hand and it would cast a shadow on the surface behind your hand.
This picture here is a pretty easy one. This is a giant tree submerged on a channel ledge. In this particular image I am scanning my Side Imaging beams to the RIGHT side of my boat so that I can get a full close up picture of the tree. Obviously you can tell that this 
tree has a lot of limbs due to the shadows that it emits on the lake bottom. This tree was out in 40ft of water it would be very difficult to find in open water. However, with the Side Imaging it would only take a matter of minutes once you got close enough to it. Once you found it you could GPS both sides of the tree on your mapping to insure you were consistently casting in the vicinity of the tree.
This would be especially helpful in the summer when the fish were suspended above the tree. If you ran over this particular cover you risk the chance of spooking the fish out of the area. Just to give you an idea, this tree is approximately 20ft tall and 60ft long.
This picture shows a group of suspended fish and a group of fish near the bottom in the same picture. The key here is to look at the distance between the schools of fish vs. their shadow emitted onto the bottom of the lake. Typically the further the shadow is away
from the fish the more they are suspended and vise versa. Kinda like putting your hand in front of a flashlight and the shadow emitted onto the wall and varying the distance of your hand which is the same concept. By knowing this kind of information you can control the depth of your lure based on what the side imaging picture is telling you.
This article doesn’t even begin to scratch the surface of how valuable and informative the Side Imaging Technology is to anglers. The above is just a select few examples of the newest technology that is available to anglers through Humminbird. There are so many situations and advantages that are unique to the Side Imaging Technology that it would be impossible to demonstrate entirely in an article format. In my two years of using this technology I have increased not only the knowledge of the layout of my home lake but I have also greatly increased my sonar knowledge.