Search and Rescue > Search and Rescue
Inexpensive sonar body targets
Spd 135:
A few days ago was was searching for a missing man in a lake in Mississippi. I was using scanning sonar (360) when I came across a good target that was in proximity of the K-9 alerts. I also was able to direct walking divers (shallow water) to another target. Divers (Gulfport Fire) went under and identified the target I found. To my surprise it was not the missing man. It was a bale of hay. The strings had broken and it had settled on the bottom. This lake is drained down for Spartan Races and the hay is part of it. There were 1/2 a dozen regular bales around the lake. A pair of coveralls stuffed with wet hay is a great target for practice. It is cheap too. We recovered the man close by this target. Images include the target, the target with a weighted milk crate and buoy and a log with 2 divers walking to it. Mark Michaud
Ohio Archer:
Good pictures. Sorry it was while you were searching for a body, though. I'd like to know how the 360 images would compare to the SI images of the same area (don't have 360).
Spd 135:
I retired in September after 24 years with Slidell PD. I continue with what I have learned now as someone has to help get the missing people home. I am currently working on a few other projects which have taken longer.
360 / scanning sonar is not as clean as side scan. But 2 state agencies and I missed him, the man we were searching for, on side scan. A body is much smaller when using side scan because you are moving. I have used side scan with good success as well. Scanning sonar picked him up. Having said that, each are tools subject to interpretation and that is key. With scanning sonar you have to be anchored (front and rear) and still. Knowing what a body should look like is key because the chance of imaging clarity is slim. Look at the 2 divers / walkers being directed to the tree. That is what you would be looking for, or the shape and pile of hay in the first images. I did get his legs/ torso in this search. You can get more clear images but it is not as necessary as the color (brightness) and size of the image.
https://www.facebook.com/Southeast-Louisiana-Underwater-Search-and-Recovery-Group-1438568169746982/
sonar2000:
Good points. something else to remember is the HB sonar display is filtered and does in fact miss bodies. That is why Humviewer is such a good addition to the recorded scan. You will probably see much more on humviewer than on the Si display on the unit. Some other considerations for target location is the angle that you approach the target. If you are looking for a body then remember that a side to side approach to the target will be a different return than a head to foot approach. Which is why we always have said in body searches that if you don't see it on the first pass then change the direction of approach. And by all means use Humviewer. Now having said that. Humviewer is for the older units not the new helix.
Now for practice in using the sonar for bodies then the best and closest target simulator is that of a 150 or 160 pound pig.
Thanks for posting your findings SPD 135.
Chuck
ckd022:
I believe Humviewer does work with Helix .son data files (at least it did with the Helix 5), I think it is the Onix data files that it doesn't work with.
Kevin
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