Humminbird Side Imaging Forums
Side Imaging Forums => Onix and Ion Series => Topic started by: nwifishnut on June 16, 2014, 10:10:54 AM
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I have a new Onix 10 and have never used SI technology before. I have a question about waypoints created in the side imaging transducer mode. I plan to use SI to find and mark fish cribs that I would later troll over using in line planer boards. If I were to waypoint mark a crib (not directly below the boat) in SI by moving the cursor on the screen until it is on the crib, is the distance from the boat to the crib/waypoint the horizontal distance over the surface of the water or the straight line distance from the transducer to the crib? And if it is the straight line distance from the transducer, then isn't the exact location of the crib relative to the surface of the water different from the position of the marked waypoint? I would assume that the actual crib location would be farther from the boat if it is a straight line calculation. I guess I am trying to understand the basic geometry of the SI waypointing process to get the bait directly over the top of the cribs.....or as close as possible to them assuming normal GPS accuracy.
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As Sonar only calculates distance from a time equation....the distance to any point in the side image is called the "Slant Range" ...or as you call it "straight line distance"...
The unit will calculate this for you...
While it's not really necessary...it can be a good a idea to recheck any waypoint made in the SI image by re-positioning the boat and rescan the waypoint with SI or 2d and verify or adjust the marked waypoint...
Robert's talks about "Slant Range" vs "Horizontal Distance" here...
http://forums.sideimagingsoft.com/index.php?topic=946.0 (http://forums.sideimagingsoft.com/index.php?topic=946.0)
Rickie
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rnvinc,
Thanks,
This answers my question and the link explains the geometry. I will verify each SI waypoint with DI/2D to ensure accuracy.