Currently have Lowrance 15mt. Considering new sonar and looking at pics such as those on page 51 of the main Lowrance Postings. It just seems the down view and the side view are of the same objects between the boat and the lake bottom. The side view/both sides left and right appear of the same down view picture under the boat and just rotated 90 degrees. Is that the way it is, where is the advantage, I was expecting more? Like a side view left and right of the boat/that being between the boat and the shore.

Down view is a just a downward view below the boat. On side view, you'll see a line in the center with black on both sides, that is the water column below your boat (down view). The thicker that is, the deeper the water. Everything to the left and right of that is the side view. That is everything that is out of the down view beam.

The width of your downview is dictated by the depth of the water. The side view is set by the user to how far out you want to see. Typical setting is 75-80' for better picture but you can set it up to 300' to either side. Distance may vary depending on unit. SO, say you are running at a depth that allows 10' wide down imaging. In side imaging you would be looking at 150' width (or whatever you set it at). You can also eliminate the water column in side view as well as just view right, left or both.

With DI you would have to drive over the top of something just like 2d to see what is below. With SI, you can keep a distance and not spook the fish and look for fish and structure. There is actually a huge difference between the two.






In this picture, I have both DI running on left and SI running on the right in split screen. On the right side of the screen you see a large object. That was picked up to the right of my boat. If you look closely at the left edge of it, the corner is just crossing into the water column below the boat and is all that I would see in DI. I had passed this thing 100 times and never saw it until because I had never passed directly over it. It took the SI to show me that it was to the right of my boat. If you look at the left side (di) just above the 4.1 MPH covering the DI screen, you'll see a little bump. That was how much of the object was in the DI beam and all you would have seen without SI, given the boat position.

Youtube SI videos and you will get a good understanding on how it works. It is amazing. I've found sunken boats and underwater bridges with amazing details with mine.

Bobby, in your picture you are saying in the down image you passed over the object as a little bump but did not know on which side of the boat it really was until it appeared on your right side image? Your left side is clear except for a slight bump right at the bottom of the water column but then clear on out to the left side because the object really is below and to the right side. In your two side views, the water column(dark) on both sides are very near the same view? I can see in your picture what you are saying. However when looking at the referred page 51 picture, the same object appears in all three views. Is that just because the object is really large and therefore shows all across the bottom and in all views?
Maybe too many questions here!
So in the side views, past the dark water column that is the same down image, I assume you are seeing the bottom of the lake on out to the side. If so then you can see objects on the bottom of the lake out to the side of the boat. What about fish on out to the side, how do they show, can you discern a suspended fish from an object on the bottom?
Thanks for your reply.

You can only see objects in DI that are directly below your boat. Anything to the side can only be seen with SI. The object may be large enough to be seen by both but it would be different parts of the object.

Yes you can see the lake floor but also anything up higher. You can tell the height by the shadow that it casts behind it. Fish will be sort of a hot bright dot or line usually with a shadow behind.

SI is a very useful tool. It takes practice to find fish but very easy to read contours, find trees, grass or anything else. You need to ask to meet someone who has it to have it explained or go to bass pro and ask questions. From your initial post it does what you were expecting it to. You just arent fully understanding how it works