Author Topic: Long-time missing drowning victims  (Read 13863 times)

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Offline plastikboot

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Long-time missing drowning victims
« on: August 06, 2010, 07:45:38 AM »
I want to search for long-time missing drowning victims in a lake in southern Germany. We already tried search dogs to make the area smaller but we all have no experience in what to expect. How does the sidescan echo of a long-time drowning look like. Can we still find a shadow? It is fresh water and the depth is only around 30m. I will use my humminbird towfish to get closer to the ground.
Anyone with experience in a search and recovery like that. Any help is appreciated.

Aquatically yours

Christian
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Offline RGecy

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Re: Long-time missing drowning victims
« Reply #1 on: August 06, 2010, 04:16:53 PM »
Most likely a drowning victim that has been in the water for more than a few months is not going to have much of a signature at all.  The body already absorbs most of the sonar and usually what you would see is a shadow.  If the body was held intact by clothing or other means, it would generate a similar result as a fresh drowning.

This would be a very interesting study.  Maybe the use of a Pig/Hog carcass dress in clothes and left in the water for quite some time would yield similar results?

Robert
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Offline xd35

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Re: Long-time missing drowning victims
« Reply #2 on: August 06, 2010, 09:50:42 PM »
A good in-sight on the very subject.

Quote
The Body in Water

The human body weighs slightly more than fresh water. Consequently, when individuals become unconscious, they sink- regardless of fat level, which slightly increases buoyancy. Generally, a drowning victim will reach the bottom of a body of water in spite of the depth, unless it meets some obstruction on the way down. As the corpse descends further, the pressure of the water tends to compress gases in the abdominal wall and chest cavities. As a result, the body displaces less water as it sinks and, consequently, becomes less buoyant the further down it goes, until it reaches the bottom.5



Quote
Rivers differ from other bodies of water in two ways-they are shallow and have currents. Depths of less than 10 feet do not have a high level of compression on the internal air spaces of drowning victims.

In extremely heavy currents, such as in flash-flood situations, the victim's body probably will roll on the bottom for a considerable distance-trees or other debris also may carry along the corpse. During normal conditions in most rivers, this is not the case, and investigators usually will find victims on the bottom relatively close to the drowning site. However, after the body floats to the surface, it may drift due to the current before washing ashore or coming to rest in a back eddy.8



Drowning Investigations
http://www.redorbit.com/news/health/400990/drowning_investigations/

Offline plastikboot

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Re: Long-time missing drowning victims
« Reply #3 on: August 14, 2010, 05:35:11 AM »
We already succeeded in locating drowning victims with the 1197. But there are still a lot missing (about 40 in just one lake) that couldn't be found in former days because of a lack of technology when the persons drowned.
I will get the chance to scan a drowning that happened 10 years ago. They left him in the lake for the training of search dogs. I will give you a summary in the end of September if it is possible to search for "longtime missing drowning victims" after 10 years in fresh water then.

Regards

Christian
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Offline plastikboot

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Re: Long-time missing drowning victims
« Reply #4 on: December 11, 2011, 03:52:47 PM »
So it is possible! I found a drowning victim after 10 years in freshwater - the reflection and shadow was incredible. I found him with a Starfish990 but had a chance to do another scan with my Yellowfin and the Humminbird 1197 towfish. The results weren't as clear as with the Starfish but you couldn't miss him; that's the advantage when scanning in muddy lakes... there is little there that can distract you. For more information you can look on www.tauchdienste.de

Aquatically yours

Christian
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Offline LocDown

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Re: Long-time missing drowning victims
« Reply #5 on: December 11, 2011, 06:21:38 PM »
That is pretty cool stuff.

Offline Rickard

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Re: Long-time missing drowning victims
« Reply #6 on: December 13, 2011, 03:25:14 PM »
Christian,
Very interesting! A young man drowned and disappeared (also his small boat disappeared) for about 60 years ago in one of the lakes I use to visit. Depth is 30 m and the water is very muddy. Do you think there is any chance he can be found with sidescan after all these years?
Rickard

Offline Jolly Roger

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Re: Long-time missing drowning victims
« Reply #7 on: December 13, 2011, 04:08:06 PM »
Gratuliere Christian!

The relatives of the victim will now hopefully find peace.

Grüße vom Bodensee / Harry
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Offline Rüdiger

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Re: Long-time missing drowning victims
« Reply #8 on: December 14, 2011, 03:45:35 AM »
Tolle Leistung Christian

Can you post some pictures off the scan?

mvh
Rüdiger
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English is not my first language !
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Offline DiveExplorer

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Re: Long-time missing drowning victims
« Reply #9 on: December 15, 2011, 04:59:43 PM »
Outstanding Christian and congratulation.

Dissemination of information and debate on this sensitive but vital issues is important to us who conduct search and rescue missions.

Thank you for posting and sharing this with us.


Offline sonar2000

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Re: Long-time missing drowning victims
« Reply #10 on: December 15, 2011, 06:32:31 PM »
Robert and I have talked about setting a section in SAR tab for informational pictures of victims. As yet we have not set the criteria for having these displayed and with respect to families we have chosen for right now to ot show any pictures.
While this is a good tool for training we want to remain sensative to the families.

So.........We would request at this time to not post victim scans.

We hope to make this available to the SAR select group but have not figured the way to keep it on this site only and restricted to applicasble SAR members only. Remember this forum has view only so anyone could see any picture right now..

Keep your scans and when we can get a suitable procedure for The SAR guys we will update the list...

Side imaging has a value and due in part to small volume of calls by teams we do feel that pictures are worth a thousand words for training. So more on this later...

Chuck

Offline plastikboot

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Re: Long-time missing drowning victims
« Reply #11 on: December 15, 2011, 07:56:52 PM »
Thanks. If it is the standard at the moment to not post any scans of drowning searches I accept that.
You should think about a procedure soon, there a lot of drowning victims still waiting for people like us to find them. Since we are all kind of "private" investigators it is very hard to get information of what to expect - but when you have seen a few scans of drownings the work is so much easier.

What I can tell from my experience with the Hummingbird and the scans of drowning victims: don't expect anything that looks like a body. I can hardly see the legs most of the time. But the one thing that all scans have in common: a shadow of an "object" approx. 30cm high. I haven't seen arms or a head in the scans at all. Most of the time the arms are very close to the body and the body lies on his front.

I really hope that the exchange of scans of drownings will help us all to bring quicker closure to the families. But it is hard to find a way to separate the SAR people from the strange ones. But I am confident that you will find a way ,)
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Offline sonar2000

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Re: Long-time missing drowning victims
« Reply #12 on: December 16, 2011, 11:09:50 AM »
PHB, you are right in that a perfect image is not normally the display image. 
Sonar is a world of training and experience. Picture swapping is a way to help in the learning process and without a large call volume it can be hard to gain the experience. You really have to try and run sonar a lot.
With regards to the peerfect image: if you have a "shape" that appears within the search area, several things can be done to reinforce the target.
1) use the 2d down color to help in both target reflection and density.
2) ROV
3) Trained cadver (water) search dog(s)
This will save wear and tear on divers. (use them only when needed)
Missing person(s) can be a time consuming event. But the more sonar we run the better we get at "seeing" the target.
If nothing else you will get used to a normal bottom and then the unexpected can pop out at you.
I remember one call in which two things were appearent.
1) no fish images
2) bottom returns that seemed abnormal for the area. did not seem to be rocks, logs or generally "stuff" associated with a river bottom.
This resulted in identifying the aircraft debris area and that indeed the craft had broken apart into lots of pieces...

We will continue to work in the SAR part of this forum and try to move towards a controlled sharing of images..

Several issues are sharing of passwords, ability to copy the picture, just to name a couple..

Hopefully 2012 will bring us to a solution to the issues.

Chuck

Offline plastikboot

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Re: Long-time missing drowning victims
« Reply #13 on: December 16, 2011, 11:54:54 AM »
Hi again,

it mind sound harsh in the first moment but could be a good way to separate real SAR from the others that want to just see photos: everyone who wants to be in the SAR exchange program has to at least give one input with a real survey he succeeded in. So only people actually working in the SAR field would gain access.
Another way is personal contact - the SAR community is just a few people so when you want to be in you have to prove yourself: telephone or skype calls give anybody the chance to actually tell why he wants to be in. Actually that might be a lot of work for you in the first place ;)
Another way to keep harm from relatives is to detach the pictures from the survey. So there will be the screenshot from the Humminbird but only limited info on the circumstances: Fresh- or Saltwater, Lake-River or Ocean, approx. depthlevel, but no time of the year, no GPSpositions and NO name of the one who did the shot. So I will send you my pictures and they might be in a database where SAR members can get the information they need to succeed but no information on the actual case that took place. That way the pics can even be used for training others.

Everything else I know about the internet and pictures is: when you can see it you can copy it! There is absolutely no way to prevent that. So we are back with trusting people! The moment you put them online you will find them going around in the internet - that will be the reality - no matter what we wish it to be.

Regards

Christian
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Offline sonar2000

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Re: Long-time missing drowning victims
« Reply #14 on: December 16, 2011, 01:01:39 PM »
Thanks for the suggestions. We will certainly give consideration to them.
You are right about the internet and that is why we are taking this slowly and thoughtfully.
We certainly dont want a picture to show up on youtube..or a facebook.
Have patience as we will work thru this and make the bottom line a move towards training and abilities.
A missed target is not much help..

Chuck

Offline Rüdiger

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Re: Long-time missing drowning victims
« Reply #15 on: December 17, 2011, 04:16:37 AM »
Hi

Piety is ok, but if you have seen such a scan, one can interpret a better chance finding.

mvh
Rüdiger
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English is not my first language !
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Offline plastikboot

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Re: Long-time missing drowning victims
« Reply #16 on: December 17, 2011, 04:34:55 AM »
One thing that we should really take in consideration: it is not the way we deal with the pics afterwards - it is about the relatives. When I ask the relatives if it is ok to present the sidescanpics so others can do the same that I did for them - all of them told me please to do so!
And to show the pics even to people that are not in the SAR member forum gives different organisations the possibility to see how it works and to consider buying a sidescan for SAR too. That will save the live of even our own divers; they can stay out of the water and only go in for the recovery itsself.

Perhaps we think too much about something that we can only clearify with each relative after each SAR survey - if they say no, it is ok, if it say yes: why not share with all.
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Offline luther_p

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Re: Long-time missing drowning victims
« Reply #17 on: December 17, 2011, 12:54:15 PM »
One thing that we should really take in consideration: it is not the way we deal with the pics afterwards - it is about the relatives. When I ask the relatives if it is ok to present the sidescanpics so others can do the same that I did for them - all of them told me please to do so!
And to show the pics even to people that are not in the SAR member forum gives different organisations the possibility to see how it works and to consider buying a sidescan for SAR too. That will save the live of even our own divers; they can stay out of the water and only go in for the recovery itsself.

Perhaps we think too much about something that we can only clearify with each relative after each SAR survey - if they say no, it is ok, if it say yes: why not share with all.
Hello to all,
I have been away from this forum for awhile due to time constraints but just dropped back in to check on the progress of others and wow, I have missed a lot.
About me, I have been in a SAR organization for over 15 years and have seen many things both good and bad related to it. This forum is one of the good things.
The topic of SI images being shown, and how, is one that should be considered but; in my experience, if the victim has been recovered, the family will be grateful that the images will help other families. Our group have a very strict policy against picture taking for this reason but a SI image is not usually an image that anyone would be able to interpret without some explanation and as such are not considered as sensitive.
In my opinion, posting an image with data relative to the scan such as water type, current, depth, bottom composition, range, sensitivity, contrast, etc., leaving out extraneous information such as coordinates, will not be harmful. Images by themselves without the data, are almost useless for training purposes.
I look for shadows of targets more than anything else. I have found that using a sensitivity setting that is higher than you would normally use to see clear bottom structure, provides a better, more defined shadow. This puts a lot of white specks on the bottom returns of the river I am usually searching in but then they can be ignored because I am not looking for specks.
Luther P
Luther

Offline DiveExplorer

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Re: Long-time missing drowning victims
« Reply #18 on: December 18, 2011, 04:16:12 PM »
I agree with many of the comments that have been discussed here earlier. Good pointers from Luther P. Of course do we need to show consideration and respect for all those involved in violence and sensitive issues. But the result of sharing information is certainly a good thing.
I hope that it would be possible to bring or make up a forum or database where people like us who are working on SAR can benefit from. And all are comfortable with that project. I have full confidence in those who are running this excellent site to resolve this matters.


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