2d cone questions

**OrangeAgent** · 05-26-2016, 02:11 PM

So let me pose a hypothetical. I am running down a fairly steep break. Say 10 feet on top 15 on the bottom. My boat is positioned over the slope itself. The sonar cone is covering the whole range of depths. So if I mark a fish on the bottom of the slope, does it show up at the same position on the graph as a fish the same distance off the bottom directly under me? What about a fish the same height off the bottom on the top of the break?

The main reason I ask is I am trying to figure out the best way to graph a drop looking for fish. Should I criss cross the drop or run it lengthways?

Thanks guys!

**genec** · 05-27-2016, 07:09 AM

ON A 2D,YOU WANT TO GO UP A DROPOFF FOR BEST RESULTS NEVER ALONG SIDE DROPOFF,ALSO IF YOU ARE SETTING ON DROP FROM 10 -15 FEET YOU WILL NOT SEE A FISH BELOW 10 FEET ,ALL WILL BLEND IN WITH BOTTOM,IF YOU RUN ALONG SIDE DROPOFF WITH 2D YOU WOULD ONLY SEE WHAT IS LESS THAN THE TOP OF DROPOFF,SI AND DI ARE DIFERENT AND CAN SEE WHAT IS INBETWEEN THOSE DEPTHS.WITH 2D IF YOU ARE IN THE 15 FEET DEPTH AND 10 FEET IS NEAR IT MAY PICK UP 10 FEET DEPTH AND SHOW IT LIKE FISH,BRUSH OR ANOTHER BOTTOM,HOPE I HAVE NOT CONFUSE YOU

**OrangeAgent** · 05-27-2016, 08:11 AM

So if I want to parallel the drop and run its length I need to stay over deeper water and watch the SI. If I want to watch 2d and get over top of them I need to run up and down the slope.

**rnvinc** · 05-27-2016, 08:45 AM

Gene is describing "Target Masking" ...wherein the bottom is painted at the shortest distance measured in the cone shape ...and other target echoes farther than this distance are painted in the bottom detail ...

This is discussed further in Sonar Quiz #25 here ...

http://www.crappie.com/crappie/side-...nar-quiz-25-a/

Rickie

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