Sonar question

[kincade]

Our fish finder is mounted on the trolling motor, my question is; if we are trolling, how fast is our finder reading? Are we seeing what we are over now or what we passed 10' ago? We got an Eagle..

[frank lawhead]

I ALWAYS HAVE MY CHART SPEED ON HIGH---I FIGURE HOW LONG IT TAKES THE IMAGE TO GET ON THE CHART AND YOU CAN PRETTY MUCH TELL HOW FAR THE BOAT HAS MOVED IN THAT TIME [CLOSE]--
IF YOUR UNIT HAS THE FLASHER BAR ON THE RIGHT SIDE IT HELPS TO START SEEING THE IMAGE START
MY BOAT IS 17' AND WHEN SPIDDER RIGGIN [SLOW]-- MY WIFES RIG WILL HANG ABOUT THE TIME THE IMAGE IS ON MY CHART [CLOSE TO CENTER] [TROLLIN MOTER]---SHE SITS IN REAR OF BOAT

[TapOut64]

Good question. The best thing to do would be to take a test run. Find some shallow structure and go over it and see when it shows up on your fish finder.

[PieEye]

Your eagle has a semi split screen with the right edge acting sorta like a flasher. That is the real time sonar and the pic is a history. It has an auto scroll or hyper scroll I believe. So what you see along the right edge is what you are presently looking at.

[Darryl Morris]

Scroll speed does make a difference, but mostly it's a factor of how fast your boat is moving. What you see just appearing on the right side of the screen is what your sonar has just pinged now. Once it reaches the left side of the display it is history and how far from the boat depends on how fast you are moving.

When we drop crappie condos, we throw a marker buoy in the middle of it. We return running the boat in a straight line at about 0.5mph. As soon as the brush first appears on the right of the sonar's display and we are even with the buoy, we mark a waypoint. Please note, the sonar's transducer position and the GPS itself are not more than a foot apart. When we come back to that brushpile our waypoints are right on the money and the sonar shows it to be so.

All in all, it's pretty much instantaneous if you have it set up that way and your boat is not moving too fast.