Side Image question - Bottom depth vs. side depth on the graph

[Spotshooter]

If the water is 20 feet deep, you won’t see the bottom until it’s at the 20 foot range line.

But if there is something “right next to the bottom” but not on the bottom - is it 20 + feet to the side or directly under you.

According to what I’ve seen if it’s in the dark water column area it’s under you, but if it shows up on the shaded bottom then its away from you...

This means the graph range is kind of screwy, because it cant’ be both 20 feet down on the bottom and 20ft to the side when it sits on the line where the bottom where the water column ends.

So so where is the “zero” for the to the right or left

[Wayne P.]

Stuff is recorded as the Slant Distance from the transducer, not horizontal distance. As close as you can get to the actual depth is where the water column meets the bottom.
You can only guess how deep a subject is that is not under the transducer and not on the bottom by seeing its shadow on the bottom.

[Spotshooter]

Hmmm...


That is what I was looking for - thanks.

[Bob B]

One of the key things to understand is the only thing the unit knows is how for an object is from the transducer. Where it decides to display that object may not always represent where it actually is.
As Wayne showed, fish shadows can be a major clue also.

Gotta let is soak in for a while if you are new to the slant range concept.

[d'Wayne]

One of the key things to understand is the only thing the unit knows is how for an object is from the transducer. Where it decides to display that object may not always represent where it actually is.
As Wayne showed, fish shadows can be a major clue also.

Gotta let is soak in for a while if you are new to the slant range concept.

Remember that 2D sonar is the same way, distance from the transducer.

[Spotshooter]

When it comes to deeper water it makes it harder.

I was chasing deep water shad (25 - 30 feet down) so it was a bit tricky, but I think I figured out how to do it via triangulation while I passed them and then turned 90 degrees.

The trick is 25 down, or 25 feet to one side ... but I could tell where they were by doing a 90 degree turn, and watching for where they appeared so I had a x, and y coordinate in some manner of speaking.

[91reddog]

Something on the surface can show up in the water column. It' gets confusing sometimes figuring out where it truly is.