Depth reading on sonar

[SirCranksalot]

Anyone with a good understanding of how the sonars work?

Here's the situation. I set up and put the xducer down. The number on the screen says 80 ft or so. I was quite surprised because I had fished that area before. My Bud #1 sets up about 50 ft away. I ask him 'how deep'? He says 40 ft or so!!I assume my FF must be acting up. Eventually I scrolled up on the zoom and found the bottom around 50 ft.!?!. Later on Bud #2, who is generally quite knowledgeable, comes along. He says  that the depth reading is showing the deepest point in the Xducer cone whereas the graph is showing the shallowest point., that we are fishing on a steep slope(drop-off)

My understanding has always been that the sonar pulse bounces off the nearest solid object on the bottom. He contends that the FF is sending out a whole series of signals (sound pulses) simultaneously(which is my understanding as well) and that the depth reading shows the deepest pt? Is that possible?

At other times I have noticed a slight discrepancy between the graph and the number shown on screen but disregarded it. The numer tends to bounce around anyway.

Comments? thx

[RapShack]

Generally they show the depth as wherever the bottom line is regardless of shadow.  You never actually said how deep the water was where you were fishing and that alone should answer your question.  If you have doubts drop all the way down, either the lure stops dropping when it gets to where the bottom is on your machine or it keeps going.

[ice dawg]

You are fishing on a slope and using chirp?

[SirCranksalot]

yes

[ice dawg]

The finder should show the depth as the highest point where the cone hits the slope. Anything under that shouldn't show on the screen. If you drop a lure down it should disappear where the finder shows bottom even if it keeps going deeper. The depth should be the same on the flasher screen and the graph screen since they get the same info from the transducer. Chirp does use quite a few frequencies. You may need to change some settings. Are you using auto for your bottom depth setting?