Humminbird Side Imaging Forums
Side Imaging Forums => 798c SI => Topic started by: docsonnys on August 28, 2011, 03:58:35 PM
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I put six spider blocks ( 8 inch blocks with black pvc pipe cemented in holes ) here but am not able to get good resolution. Cannot tell the blocks from rocks? fish?. Have tried various sensitivity/contrast/colors. Could it be my transducer?
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Try bringing the range down to around 45'. 8" blocks are not that big! I see quite a few rocks or blocks on the left and a few on the right. The pvc is round and doesnt reflect the sonar very well.
Did you get GPS coords on exactly where you dropped the blocks? This may help in identifying them for future.
I do see some suspects on the left that look like they have a good shadow. Remember, you will be able to tell more about an object from its shadow than from the sonar return.
Robert
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I would also record your run and then play it back on the unit so you can fiddle with the settings to see if you can get a better image.
Robert
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For what it's worth I sank an old basketball goal a few days ago in 15 feet of water. This is the 5 inche metal post with metal framed backboard and goal attached. (Portable driveway type goal) It took me at least 20 scans before i even "thought" I saw it on a scan. After recording and going to hum view I am pretty sure that I have located it (multiple gps coords for same object) but it looks absolutely nothing like I expected. Former poster was corrrect in that the roundness of the pipe does not give a good return. I am beginning to think metal is even worse than pvc and only shows a faint line on the thin edge of metal that reflects the sonar directly back. Will post some scans in few days along with a picture of the original goal for anyone who is interested.
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some scans of the goal. Looks nothing like original to me...except last couple of pics
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And here's the original for comparison.
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I don't know what you're talking about HarrisonDawgs... I went over the area and this is what I saw... ;D
(http://img.dailymail.co.uk/i/pix/2008/05_02/goldfishSOLENT_468x364.jpg)
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Wingnut,
Pardon please! I screwed around with the settings and tried another scan and found the goal. Now if I could identify the HUGE fish hiding behind the backboard! >:D
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HDawg, I have seen that fish before..
It is called a loudmouth bass. Often seen in well fished lakes.. ;D
Chuck
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An 8” block is not a large target to look for, especially if it was dropped over a soft bottom as it may have sunk into the bottom and not left much of a profile sticking above the bottom. PVC like most plastics are not good reflectors of sonar. Metal is but if the size of the pipe is small than so will be the reflected sonar. Try attaching something that is air filled the next time you drop those spider blocks and you will be able to spot them easier. Maybe a syrofoam ball or sealed bottle with air in it.