Hard Bottom Hump

Hard Bottom Hump

This series of screen shots and maps will tell a story about a small hard bottom hump and the accuracy of bottom hardness maps. I collected the data with the Lowrance HDS log chart feature. The first map is a depth contour map overlaid on the bottom hardness map. I set the depth contours for one foot in DrDepth and saved a map image to get this picture. This hump has hard bottom extending into deep water. I have seen this often on Minnesota lakes. Walleyes likes transitions and drop offs so they have choices on this hump.

I played back the sonar log on the bottom hardness outline overlaid on 2 foot contours created by DrDepth) in my Lowrance HDS to check accuracy. The boat (vessel) cursor position would correlate with the far right side of the sonar. What is below the transducer is always the far right part of the display that is being printed.

$C:\Documents and Settings\Bruce\Desktop\DD test\hard hump 1edit.png$

Compare the photos like a slideshow as I move across the hard bottom capturing screen shots at different places. I teach bottom hardness in my Sonar DVD series but here is a brief summary. The thickness of the bottom band shows differences in bottom hardness better than the colors. Hard bottom thicker band, soft bottom thinner band. Remember what is under the boat is the far right side of the sonar display.	$C:\Documents and Settings\Bruce\Desktop\DD test\hard hump 3.png$
The data was collected with my HDS at high quality. DrDepth can use the data collected at low quality but I always record on high because we have lots of cheap memory on the SD cards and lots of memory on the computer hard drives. The higher quality allows a clearer picture if you want to study them in the HDS simulator, the computer emulator (coming someday from Lowrance) or the SonarViewer (a new one is coming someday from Lowrance). All of these tools will re-play your logged files just like a DVD player. I was amazed at the accuracy the DrDepth BT Edition creates bottom hardness maps. I was too focused on tournaments this year to collect data to experiment with; I will be more alert next year!	$C:\Documents and Settings\Bruce\Desktop\DD test\hard hump 4.png$
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	$C:\Documents and Settings\Bruce\My Documents\My Pictures\Electronics seminar\Mapping Seminar\DD\hard hump\hard hump 6.png$