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  1. #1
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    Question Understanding Side scan WP placement




    In the screen shot, We ran over something that I wanted to mark. I thought they might be fish, but we didn't catch so I can't confirm.

    Since we split the objects between left and right, that should mean we ran almost directly over them. I do see that they are probably more to the left of mid since the return is stronger on that side. I placed WP 355, 356 and 357 in a line to mark it.

    Out of curiosity for this question session, I marked 359 and 358 on the fish, left and right of center.
    Then out to the side I marked a stump/log (360).

    1. Am I marking it wrong with 357, 358, and 359?
    2. If you look at the map in the top right, you see that 359 and 358 (blue line) are out to the side in either direction. If the fish are relatively close to being directly below, surely they aren't out 20' (as this is the depth) in either direction. What is going on here, I would expect that 359 and 358 be directly under the boat, or fairly close to it?
    3. Is WP 360 actually 40 foot from 359 (green line) and 60' from the transducer?

    I may be over thinking it. Maybe I should be accepting that the software is capable of doing the math and marking what I see accurately, but it throws me off with how 358/359 is shown to either side of 356 in the map. I just want to trust the WP placement and then be able to hit it.

    Last edited by Jethreaux; 02-12-2018 at 09:25 PM.

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  3. Member WB's Avatar
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    #2
    20 feet is a boat length
    .

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    #3
    Quote Originally Posted by WB View Post
    20 feet is a boat length
    .
    unless its a 20' 11" boat, then its almost a foot short.

    20' off can be make or break on a spot. In this case, it could be almost 40' between 358 and 359

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    #4


    Don't have the answer, but I'm wondering the same thing.

    I often mark spots and it may say they are 40', 60', 80', 90' out to one side, maybe in 15'~20' of water.
    Yet I know ABSOLUTELY that 80' out (if not 60') and it'll be up on the darned BANK! (Or at the very least in 12"~18" of water.)
    Later,

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  6. Member
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    #5
    Photobucket may have been a bad choice...recommendations for an image host to use that won't stop the screenshot from showing?

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    #6
    I don't know if I'm doing it right, but when I see something in the "water column" on side scan, then I mark the WP on my 2d or di screen (I always run one of those along with si). My thought is that would be directly under the boat and not off to the side. Can't see your image though so don't know if that would make it any different or not?
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    #7
    Quote Originally Posted by Jethreaux View Post
    Photobucket may have been a bad choice...recommendations for an image host to use that won't stop the screenshot from showing?
    I corrected it with google drive, by creating a drive direct link and embedding it with the HTML editor...long story, but better than using stupid photobucket.

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    #8
    Quote Originally Posted by rat0502 View Post
    Can't see your image though so don't know if that would make it any different or not?
    You should be able to see it now.

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    #9
    Did I put this in the wrong forum? it's been *crickets* in here...

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    #10
    This is how I read the waypoints. 355,56 and 57 are under the boat. 359 and 358 are 20ft to each side of the boat. 360 is 60ft from the boat and 40ft from 359. The range marks are not showing anything for depth but rather the distance out to the side of the transducer.

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    #11
    I see 355 356 357 directly under the boat 358 is 20ft to the right of your boat. 359 is 20ft to the left of your boat and 360 is 60ft to the left of your boat and 40ft from wpt 359

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    #12
    Sorry i just read Indiana01 post and realized he said the exact same thing..

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    #13
    Quote Originally Posted by jt c View Post
    Sorry i just read Indiana01 post and realized he said the exact same thing..
    NP, good to know more than one of us are looking at this the same way.

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    #14
    OK, need more people to chime in help out Jethreaux as i am not the expert and I just got this PM telling us we are wrong

    You guys are clueless about the side looking imaging technology.

    The only waypoint that is not under the boat is #360. That one is 60' SLANT RANGE from the transducer. It is not horizontal distance from the transducer. The technology does not show horizontal distance if the water column is displayed.
    With the original recreational side looking imaging that Lowrance copied (Humminbird Side Imaging) you can turn off the water column and see the horizontal distance displayed.

    358 and 359 are at the junction of the water column and bottom=DEPTH. There is no distance away from the boat involved.

  16. Member Wayne P.'s Avatar
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    #15
    Look at this video:

    Wayne Purdum
    Charlottesville, Va.
    Helix 12 SI, ONIXCI 10 NT SI, 1198c SI, 1198cSI, bow 360, RC-1
    1.640,--------3.230, ----------------7.670, ----7.670-----2.030
    SOLIX 12 SI, Helix 7 CHIRP SI GPS G2
    3.230,----------1.640

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    #16
    Quote Originally Posted by indiana01 View Post
    OK, need more people to chime in help out Jethreaux as i am not the expert and I just got this PM telling us we are wrong

    You guys are clueless about the side looking imaging technology.

    The only waypoint that is not under the boat is #360. That one is 60' SLANT RANGE from the transducer. It is not horizontal distance from the transducer. The technology does not show horizontal distance if the water column is displayed.
    With the original recreational side looking imaging that Lowrance copied (Humminbird Side Imaging) you can turn off the water column and see the horizontal distance displayed.

    358 and 359 are at the junction of the water column and bottom=DEPTH. There is no distance away from the boat involved.
    I agree to 100 % with that statement! But what I don't really understand and what the TO asked in his opening post: If there is no distance away from the boat involved (what is absolutely correct!), why are WP 358 and 359 created with a distance of 20' (=depth) from the boat?

  18. Member pavi69's Avatar
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    #17
    Quote Originally Posted by Sasch View Post
    I agree to 100 % with that statement! But what I don't really understand and what the TO asked in his opening post: If there is no distance away from the boat involved (what is absolutely correct!), why are WP 358 and 359 created with a distance of 20' (=depth) from the boat?
    358 & 359 are the same spot basically straight down from the transducer. 355, 356 & 357 are the bottom of the transducer.
    She laughed when I tried to tell her
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    #18
    I know, but if it is the same spot, why are the Waypoints created with a distance of 40' to each other?


    Quote Originally Posted by Jethreaux View Post


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    #19
    Quote Originally Posted by indiana01 View Post
    I just got this PM telling us we are wrong

    You guys are clueless about the side looking imaging technology.

    The only waypoint that is not under the boat is #360. That one is 60' SLANT RANGE from the transducer. It is not horizontal distance from the transducer. The technology does not show horizontal distance if the water column is displayed.
    With the original recreational side looking imaging that Lowrance copied (Humminbird Side Imaging) you can turn off the water column and see the horizontal distance displayed.

    358 and 359 are at the junction of the water column and bottom=DEPTH. There is no distance away from the boat involved.

    That wasn't a PM from me by the way.

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    #20
    Quote Originally Posted by pavi69 View Post
    358 & 359 are the same spot basically straight down from the transducer. 355, 356 & 357 are the bottom of the transducer.
    I understand that the objects are X distance away from the transducer

    I suppose to test the theory and answer my own question, I should go back to this location and start at 358 and travel to 359 with the trolling motor to verify that there is not 40' distance between the two way points on the map? Am I wrong? That is what I was struggling to grasp.

    If you split the object which should mean you passed directly over it, and you place a way point on both halves of the object, in theory the points should still be right on top of each other on the map. You can obviously see that that is not the case since I provided the map and the side scan split screen. You can see the map scale, in the bottom right corner, at 100 foot confirms that there is a distance between points 358 and 359.
    Last edited by Jethreaux; 03-01-2018 at 10:04 PM.

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