Got my set up ready to go. Next tuedays my trip on my kayak will have the fish finder working. My question is probably stupid but after watching every video on youtube almost o one says. Now when you are sitting still why does the image still scroll on the screen? What is is scrolling if your boat is sitting still? How can you tell where the fish on your fish finder is in the water?

Just now, Fred Allen said:

Now when you are sitting still why does the image still scroll on the screen? What is is scrolling if your boat is sitting still?

Finder can't tell if you're moving or not - so it just scrolls the screen at the same-set speed. You can adjust the speed of the scrolling on some models, but you can't stop it.

1 minute ago, Fred Allen said:

How can you tell where the fish on your fish finder is in the water?

Standard chirp sonar is sent and received in a cone - the deeper the water, the more area is covered. If you're sitting still and a fish swims into the cone and appears on the screen - it could be anywhere in that cone...in front, to the sides, behind, etc...no way to tell where it is other than it's in the cone.

If you sitting still you won’t get arches. You get straight lines. 

Whether you’re moving or not, your transducer is still pinging beams down and receiving new returns every second. So it’s receiving new information even tho you’re in the same spot, therefore your screen is still scrolling displaying the new information the transducer is receiving.