Topic: Interesting sonar observation

[sonar2000]

Ran sonar on a mission today and came accross a bit of a problem.
Water depth 30 feet. distance to shore 25 to 75 feet
Shore line was about the same depth as the boat depth.
Shore had floating docks parrellal; for boat parking.
Interesting that side image would show all bottom data ok but the top 8 to 10 feet of depth was hidden by the floating docks.
this is normal as the docks do prevent the signal from going in that direction, but interesting that the target we were seareching for could have been in the top 10 feet and hung up and no way to get sonar to see it..
We could eliminate the bottom as target free but could not say the same for the top depth.

This is a procedural issue and not a product defect. But in SAR we could not discount a large piece of the shore line..

This post is just a FYI and I will be looking into this some  more. One step in the process would or will be to get dogs to sniff the area if sonar cant see all of it.

I just found this interesting..and frustrating as we did not expect it or would have had dogs there also..But now we know next time..

Chuck

[raricker]

Hi,
I know nothing of the challenges of SAR work so I'm just guessing on this. My knee jerk reaction to your observation/problem would be to move the boat further away the floating dock to allow more of the SI beam to penetrate underneath that obstruction.

I'm not telling you how to do your work, but that's my thought.

Take care,
Roger

[ITGEEK]

Hey Chuck,
Have you guys ever used really good quality underwater video cameras?
I would think if the water is clear, that it could be another helpful tool
for your line of work.

[sonar2000]

ITG, yes we have the equipment.  Unfortunately the water has no visibiolity as in "0"..
Additionally, there is so much intanglement you could not even use an ROV. And add to this and that it is tidal affected with very appreciable current. This also affects  divers and ability to function.
In differrence to the mission, this is a difficult environment but we have to do that which we can do safely.
Unfortunately, the family still has a missing loved  one.. \\

Chuck

[Humminbird_Greg]

With your portable Si system could you have boarded each dock and dropped an Si transducer on a pole over the side of each dock and scanned that way?  I imagine that dogs would go quicker but if you did not have any dogs there…

[Roddy]

ITGEEK, Video cameras work best at fixed points or on a ROV.
             Visibility is the big problem, Evan with IR and enchantment software.

             I use a wide variety of tools and each has its capability's and limits. As yet there no universal do it all!!!!

             Keep pinging and enjoy!

             Roddy

[sonar2000]

OK, thanks guys, I did not want to skew off on this as the original post was to show a considertion for sonar runs.

Managing the event is a whole other posting..

Thanks for the comments..

Chuck

[sonar2000]

Greg, just caught your post.
Yes we had dogs on the way.
No a dropped transducer (even something like the 360) or other vector scanners would not be able to see back in the area because of posts, poles, supports, etc.
Since our "stuff"  is portable we did try to to set the transducer and then spin it by hand to see what it would do. Did not work.  And another  thing about this. We had an area about 5000 feet in length. It would have taken days to move a foot and try, move a foot and try.

Again the intent was to point out the  dependency of sonar have a clear line of sight signal. The need to know your equipment and operate it accordingly to produce meaningful data which can be acted upon..Sonar is more than open the box and turn it on..

Anything else around this becomes search management concerns and plans.
In the ICS language it is called situational awareness and Objectives, Strategies and Tactics..
Chuck

[Danco]

Just a thought.  Would the 360 imaging system help with that application.