Because thats how deep it is.

Because it's shallow water.

Pardon my ignorance on the matter, but I have never dabbled in SI. Now I understand the width is 200', but the small size of the tire is what was throwing me off.

I just measeured the picture with a ruler on my computer it was 110MM on each side from eadge to centerline. The Single Tire I point at is a little over 3MM or roughly 3' in size. Which is about the size of a car/truck tire. The area of coverage you view will change the size of the objects. If I would reduce to 50' area of coverage the single tire would double or be close to 6mm in the image but still be 3' in real life. If I would increase the area of coverage I was viewing to 200' the data would be even smaller so the tire would be 1.5mm since I doubled the area of coverage but would still be 3' in real life. THe smaller the area of coverage the larger the objects but less area that is being viewed on the screen. Too large and it's hard to see the very small details like small branches, smaller fish, etc...that is why using the area of coverage which is user selectable in the XPres Menu (Hit Menu Once) will allow you to adjust the area of coverage to make it easier for you to view. I personally like 100' on the 1198c which is what captured this image and the 10.4" Screen. Small details are large enough to see but I get alot of coverage. Coverage is the NUMBER 1 Benefit of Side Imaging being able to scan a large area of water no matter the depth and see what is away from and under the boat in a single pass.

That makes sense I think. But why does the tire at the top of the screen look so small? Its closer to the boat, so you would think it would be more "lifesized"

It's the same size. 3MM as the single tire off the point. Looks the the tire on top right is not silted in as much. Or could be a wider tire...

Doug what would be your recomendations to set my 798SI Di? I have tinkered with it but haven't been able to fine tune? Any help would be greatly appreciated.

This video explains my setting recommendations: http://www.youtube.com/watch?v=YV-Rh8wXTY0

Doug,

Your youtube video is a great help. I have had my 798SI DI for well over a year and I felt the video was a great help. Also, with the 798 I have been using only one side on SI and running between 50 and 65 feet and feel that has helped me greatly. I'm just trying to make the images a little larger. I have also found that switching color pallets for the lighting conditions has helped certain objects stand out with more distinction. I test to see which settings give best contrast between bright objecs and shadows. That seems to help me with the overall view. I hope that makes sense.

Ron