Thread: Help Me Understand This......

Originally Posted by Buzz

It could even be in another lake, in another state.

(especially if you never turned the simulator off like me)

Buzz

From why I understand, that when you see something come on to the right side of the screen, it is under you. But the time it gets a 1/4 inch on the screen, you are past it. Hope this helps.

Joking aside, this is a tough thing to learn and even a tougher thing to explain. Let's take a stump in my example that's 3' tall and 3' around. Let's say it was cut off by a chain saw. Let's say it's in 20' of water and you're using a 20 degree ducer. Somebody check my math on this, but the area of overage would be a circle roughly 40' in circumference. Further, let's say your ducer is on the TM.

OK, now, as you approach the stump as soon as it enters the ducer, which has coverage 20' ahead of the boat, it shows up, or at least start too. As you continue on, the signal gets stronger and the image climbs on the screen until you get right on top of it, when it is directly below the ducer. Again, as you continue on, the ducer continues to pick up the stump but with less strength untill you're 20' past it and the image decreases in height as you continue on. So, the stump doesn't show up as it actuall is like this:
___
| |
| |

It most likely shows up as varying degrees of signal strength and return, depending on how fast you're going and your scroll/chart speed like this.


^
/ \
/ \

OK, so how do you know if it's 20' to the left, right or center. Well, this requires trial and error and movement.

Let's assume you approach the stump running due north and pass the stump 10' off your port side to the west. As you approach the stump, the image climbs, when you're as close as you're going to get in my example, it begins to fall. As it begins to fall, let's say you guess it's to your right or East, so just as the top of the image begins to fall, you turn the TM to the right, but the image continues to fall. You then correct and steer back to the west and the image again begins to climb. Now as you pass over it, again the image peaks and you can confirm it's position by steering left and right looking for the peak of the image.

Now the hard part. You never really know what's down there nor the shape of the object, so a wad of brush will usually have a single highest point, usually somewhere near the center. A stake bed will have multiple tops over an area. A laydown log could have several high points. You really just have to move and make a mental image of what is there.

Lots of patience, practice pays off. Also, when you find something that looks interesting. Take a jig and work it and that'll help tell you what is down there and how it is oriented as well.

Or, you could just go get a 1197SI, find what you want, move your cursor over it and mark it. But that takes all the fun out of it.

Wannabe...

Originally Posted by rdant

From why I understand, that when you see something come on to the right side of the screen, it is under you. But the time it gets a 1/4 inch on the screen, you are past it. Hope this helps.

Not positively true. It depends on the cone angle, depth of water, system sonar settings, etc.

Extreme right side (or A scope) is real time display. All display after that is history. A Scope is the flasher display kinda.

Lowrance has a good tutorial on this subject (as mentioned).

Below is a quick reference chart for the area covered by the specific cone angle listed. For example, if you are fishing in 10 feet of water and the cone angle on your transducer is 20 degrees, the area across the bottom is 3.5 feet.

* 20 degrees - 0.35 or roughly 1/3 of depth
* 24 degrees - 0.42 or roughly 2/5 of depth
* 30 degrees - 0.53 or roughly 1/2 of depth
* 40 degrees - 0.72 or roughly 3/4 of depth
* 50 degrees - 0.93 or roughly 9/10 of depth
* 60 degrees - 1.15 x depth
* 70 degrees - 1.4 x depth
* 73 degrees - 1.48 x depth
* 80 degrees - 1.68 x depth
* 90 degrees - 2 x depth
* 100 degrees - 2.38 x depth
* 110 degrees - 2.85 x depth

Find it on the graph. Throw marker in water in vicinity. Come back through in flasher mode and pinpoint. The flasher is money.

When I slow to no wake and im looking I get a marker ready if I see something I drop it over the side and it will pretty much be with in 4-10 ft behind it in 10-18' of water.

Thanks Cane Pole. I knew my rule of thumb didn't sound right.

Now if I can just rember......1/3, 1/3, 1/3, 1/3.

Nope, I've forgotten already.

Wannabe...