Humminbird Side Imaging Forums
Search and Rescue => Search and Rescue => Topic started by: steverfd on July 31, 2010, 11:58:48 PM
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Ok we got the unit mounted and works well except for some turbulence we are picking up on the left side when the engine is trimmed all the way down....With the engine trimmed up a small amount the turbulance is no longer there.
Now I need a way to begin training on the unit. I need something that will give a good signature that we can construct or pick up so that we can work with the different users to improve their skills in the use of the unit. We have a local lake that is shallow but is easily accessible by out on duty personnel so we will only be dealing with depths of 10 feet or so.
Still playing with the settings to get it tweaked out for detail.
Thanks,
Steve
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Steve,
I moved this thread to the SAR forum.
I am sure Chuck will chime in on this topic also and share his thoughts. A few good items for training:
Tires are good for just getting speed and chart speed settings matched. You want the tire to be round on the screen, not elongated. Keep the SI range low, less than 60ft.
A wild hog carcas works good for simulating a body. It has similar desitity to a human body and you can usually find farmers around who are willing to let you kill all you want.
Steel pipes to represent gun barrels. Steel objects will give a good hard return, but since the barrell is skinny, it is important to run scans at 90 degrees to each other since you could eaily miss it if the barrel is lying parallel to SI beam.
Hope that helps,
Robert
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We started out using a wire cage, very good return, tires are good. Make sure boat operator runs straight line grids so as not to distort the SI. Good suggestion on running 90 degree cross tracks. Take screen shots and look at them on your computer, so much more detail and finally a lot of water time over known objects will get you team up to speed. Hope this helps.
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I responded earlier to his PM with ideas.
For SAR in a nutshell, it takes a lot of time to get good with the unit.
External viewing programs will often show targets that dont show up on the unit screen when recording or viewing.
Running straight line patterns with a second 90 degree pattern(s) will make sure you have covered the area well.
The most important thing for sonar is to produce two things:
1) the object of interest
or,
2) (and this is equally important) is to show that the object does not exist in the search area.
Which is why you need to be very good with the unit and have experience to make a statement that will support a 99% POD.
Divers are good for only a short time and area so when the initial diver search does not produce the object, sonar is the next step.
An experienced operator will take less time to search the expanded area. And safer for the diver.
Chuck
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We have the luxury of having several sunken fishing boats that we have dove on and we know the exact dimensions. All 6 of these boats are different shapes but in the 20' to 30' depth range so the images are congruent with each other. I have taken some images of a 23,000 pound dumprtuck and a 1 ton van that are sitting 75' from each other in 104' deep water. I only took one recording of these two objects using two SD cards but the recording started on the card that was almost full so when I went to review it on the Humviewer, the recording was corrupt. The screen on the 1197 showed the two vehicles but if you did not know they were there I would have dismissed them as a small rock and not a large vehicle. I was depressed that the target was un recognizable at the 100' depth on the screen of the 1197. I have heard of people dropping a large plastic dog kennel (with a small anchor inside) next to a drowning victim to use for a scale of the known dimensions of the dog kennel compared to the body. We have tried to suspend 120 cubic foot steel scuba cylinders from a lift bag to see what a suspended object would look like but the round cylinder doesn't show up at all even when sitting on the bottom. This is probably because of the echos bouncing back at a different angle on the round object kind of like "stealth" technology. We have also tried to take images of a 15' tall lifeguard tower that was made from 1.5" round steel tubing sitting in 30' of water and the same effect with not much of an image on these round objects. The dog kennel trick is about the best one I have heard of but I have not tried it.
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The dog kennel is also very nice because it can be folded up and stores easily. Not to mention it gives a nice return.
Robert