Why StructureScan Side Imaging makes a difference in all types of fishing


To understand why StructureScan makes a difference in all types of fishing, let us first make sure we know the fundamentals of what we are looking at and the terminology being used.


StructureScan - the combination of Side Imaging and down imaging


Side (Scan) Image can be on the left side and/or the right side of the boat


Down (Scan) Image (DI) is the conventional Fish Finder like view which is presented in a cross section, but is scanned at 455 or 800khz, giving a more photo like display.


Sonar (Fishfinder) is the conventional Fishfinder view



Looking at this image, there are 3 panels. The left hand side of the screen is a left side image. The sea surface is in the middle of the screen above the letter e (in the word Range) and extends all the Way up to the top of the screen. The column of water is shown in the black expanse to the left of the surface and the sea bed is at 20 feet below the surface taking up the rest of the content in this panel.


The top right hand side of the panel is a down image. This shows the traditional Fish Finder cross sectional view, but because of the much higher Frequency, provides an almost photo realistic image of 2 divers walking on the bottom tethered together.


The bottom right hand image is the conventional sonar view. Notice the unfocused difference to the image above. There is something down there, but we have no idea what it is.




Looking at this image and comparing it with the one above we now see in panel 1 on the left hand side of the screen, both a left and rightside image.


Notice that the top right hand down image shows the two trees, but has no concept on which side of the vessel they are located.  Only by looking at the side image in the left hand panel did we learn that most recent tree was on the Starboard side and the earlier tree was on the Port side.


Again the sonar image knew that something was there but had no idea what is was.


Notice also that there is a shadow behind each tree. If you held your hand vertically and shone a torch on it you would get a shadow. Think of Side Imaging in this way




The image above is composed of: Left panel - down image, right panel - full side image. Note screen proportions have been manually adjusted to make side image panel use 66% of total screen space

This is our game fishing hero shot - if you are chasing Yellow Tail King Fish or Tuna pay attention! This time the screens are switched around with our down image in the left hand panel and we can see that there is a bait school underneath. With a conventional sounder or a Down Imaging unit, we have no idea where the bait school is. Only by looking at the side image panel on the right do we learn that the majority of the school is on the Starboard side and so we would turn to Starboard to go around them.


Note also that there is some man made structure on the Port side. With structure there is habitat. With habitat comes aggregation. Only by the triple use of side image, down image and Sonar image do we learn about what is happening and where.  A sonar view will amplify a Fish image so it is better to use this view to find individual Fish.



Here we can see a transition from sand to rock and weed.



We know we are on sand as we can see the ripples that the waves have created on the sea floor. Again the transition for sand to rock is clearly apparent.



In the top right hand side we can see our Sonar view of a large baitball being munched on by a predator (at 10 o'clock position). This is more apparent in the bottom right hand side, down image view.


So what have we learnt?


In our view, Down Imaging (DI) units are only providing half the story. To get the complete picture, buy a unit capable of all three - side imaging, down scanning and sonar.


These Lowrance models all have StructureScan abilities:


Simrad : NSS7, NSS8, NSS12 (require ESA702 LSS-2 Black Box & Transducer option)


Humminbird : 798cxi HD SI, 898c SI, 998 HD SI, 1198cx SI