Captain Yak wrote:
What type of depth do you fish and do you typically mark fish? I haven't marked a fish unless it's right below my kayak.
I fish freshwater at depths down to about 150'. The water in the winter is often very muddy.
I am a bit confused by the statement of only marking fish right under the kayak. I am probably misinterpreting what you wrote, but want to respond in case I am not.
Any time you see an arch you are seeing the fish from the time it enters the cone until the time it leaves the cone. In 100' the 25 degree cone of the 2D sonar covers a circle with a radius of 100*tan(12.5) ~= 22.2 feet (diameter of 44'). Thus you can start to see fish on the bottom that are in a 44' diameter circle (start of the arch). That is a fair bit more than directly under the kayak.
Fish tremble when they hear my name
A ship in harbor is safe -- but that is not what ships are built for.
--John A. Shedd, Salt from My Attic, 1928