<div dir="ltr">I bought a cheap depth sounder/fish finder that I thought I would mount up front facing horizontal and my thought would be that if I were trying to locate a wreck or an atoll that was out of visibility, assuming that the bottom was relatively flat, I could rotate 360 degrees and look for a depth that was showing close. I would probably have to rotate very slowly for it to show but I figured for the price, it was worth trying. I spoke with Garmin who built it and they weren't sure it would work in that capacity as the signal comes out as a cone and if I was close to the bottom, I might be picking up the bottom right away? The did sell much more expensive forward looking sonars for yachts but trying to keep my costs down per wife. I will probably take it down to the dock and clip the transponder to a stick and hold it horizontal just underwater and see how it does. I'll let ya know the results when I do.<div>Rick</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, May 18, 2019 at 7:26 AM Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="font-family:Arial,sans-serif;font-size:10pt"><font size="2"><font face="Arial, sans-serif">Tim, </font></font><div><font size="2"><font face="Arial, sans-serif"> Yes that's the idea. On my Garmin depth finder there is an optional screen which is simply stationary screen and then there is the screen that is moving , which gives you a "history" of the last few seconds of scanning . But it would be interesting to play around with the detect ability of something like that. Not sure how practical it would ultimately be. </font></font></div><div><font size="2"><font face="Arial, sans-serif"><br></font></font></div><div><font size="2"><font face="Arial, sans-serif">Brian</font></font></div><div><font size="2"><font face="Arial, sans-serif"><br></font></font></div><div><font size="2"><font face="Arial, sans-serif"> </font></font><br><br><span style="font-family:Arial,sans-serif;font-size:10pt">--- <a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a> wrote:</span><br><br><span style="font-family:Arial,sans-serif;font-size:10pt">From: T Novak via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span><br><span style="font-family:Arial,sans-serif;font-size:10pt">To: "'Personal Submersibles General Discussion'" <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span><br><span style="font-family:Arial,sans-serif;font-size:10pt">Subject: Re: [PSUBS-MAILIST] passive sonar</span><br><span style="font-family:Arial,sans-serif;font-size:10pt">Date: Sat, 18 May 2019 07:15:35 -0700</span><br><br><div style="font-family:Arial,sans-serif;font-size:10pt"><p><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Brian,</span></p><p><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">What are you trying to do with the "passive sonar" that you are considering? Are you wanting to make your submarine more easily detectable by a surface boat with a depth sounder?</span></p><p><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)">Tim</span></p><p><span style="font-size:11pt;font-family:Calibri,sans-serif;color:rgb(31,73,125)"> </span></p><p><b><span lang="EN-US" style="font-size:11pt;font-family:Calibri,sans-serif">From:</span></b><span lang="EN-US" style="font-size:11pt;font-family:Calibri,sans-serif"> Personal_Submersibles [mailto:<a href="mailto:personal_submersibles-bounces@psubs.org" target="_blank">personal_submersibles-bounces@psubs.org</a>] <b>On Behalf Of </b>Brian Cox via Personal_Submersibles<br><b>Sent:</b> Friday, May 17, 2019 8:35 PM<br><b>To:</b> PSubs <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>><br><b>Subject:</b> [PSUBS-MAILIST] passive sonar</span></p><p></p> <p></p><div><p><span style="font-size:13.5pt;font-family:Arial,sans-serif"> I've been thinking about some sort of pinger locator for my sub. I may get a commercially available one just as an extra safety measure, but in the mean time I was playing around with my depth finder on my sailboat . I was thinking if I had a rotating disk that would be a little higher than the sub the changing surface exposure to the sonar waves would appear on the depth finder as a recurring blip . I tried it with a radar reflector that I have, I tied it to a line and located it just below my transducer, I was able to move it around and observe the display on the screen. Since the radar reflector ( used on boats so big ships can see you) has all these sides to it, as I moved it around it would show up intermittently since the sound wave sometimes would not bounce back. I think a flat surface rotated so only the edge is showing and then a large surface was showing at a regular intervals could work as an indicator. I might be especially valuable if you were blending into the bottom so much as to not be detectable . That way someone with just an ordinary depth finder could detect you. </span><span style="font-size:10pt;font-family:Arial,sans-serif"></span></p><div><p><span style="font-size:10pt;font-family:Arial,sans-serif"> </span></p></div><div><p><span style="font-size:13.5pt;font-family:Arial,sans-serif">Brian </span><span style="font-size:10pt;font-family:Arial,sans-serif"> </span></p></div></div></div><span style="font-family:Arial,sans-serif;font-size:10pt">_______________________________________________
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