PWCPD Diver
Guest
Besides Fan searches with a hardline/line handler and jack stay(without line handler)searches. What other types of search techniques for both evidentiary searches and body recovery do you use? Just curious...
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ItsBruce
Contributor
I've never done an evidentiary search or a body recovery. However, we are setting up to search for a sunken boat. We've got a good idea where it is...give or take a quarter mile. We will use about 10 divers spread out perhaps 40 feet apart on one very long line and we will swim until the line snags on the boat. I'm still working out how to communicate among the divers. I'm also working out how to deal with snagging something unexpected. If you've got any ideas, I'm open. If you want to join us, let me know.
Hi ItsBruce;
Way to many divers in the water to conduct a safe operation.
What's the boats size, vis and depth like?
Anybody have a Fish Finder on their boat? Take advantage of it. We were using them 30 years ago with great results for larger targets and even bodies. Just run it until you get some targets. Mark them with "H" floats and send down a diver or two to take a look at what you have.
There are some Fish Finder tricks you can use to pin point a target. I'm going to just use north as a starter.
You hit a target going north at say <5mph. Toss a surface marker out.
Turn and head back at the float going south. Now with someone watching the screen and nothing else, as soon as they see the target appear, toss another float over the stern. I MEAN AS SOON AS THEY SEE THE LEADING EDGE OF THE TARGET APPEAR. NOT THE TARGET, toss the float.
Do that from at least 4 directions and your target will be in the center of the floats.
It works great and the more you practice the better you get at knowing the unit you are using. Most cones from the units are 21 degrees. So figure on the view you see of the bottom is roughly one third of the depth. 100’ bottom you will be seeing a 30-40 feet circle.
Most of these units have a ZOOM feature in them. Once you see the target keep going over it while zooming in on it. You might be surprised at the picture you will get.
Good luck.
Gary D.
Way to many divers in the water to conduct a safe operation.
What's the boats size, vis and depth like?
Anybody have a Fish Finder on their boat? Take advantage of it. We were using them 30 years ago with great results for larger targets and even bodies. Just run it until you get some targets. Mark them with "H" floats and send down a diver or two to take a look at what you have.
There are some Fish Finder tricks you can use to pin point a target. I'm going to just use north as a starter.
You hit a target going north at say <5mph. Toss a surface marker out.
Turn and head back at the float going south. Now with someone watching the screen and nothing else, as soon as they see the target appear, toss another float over the stern. I MEAN AS SOON AS THEY SEE THE LEADING EDGE OF THE TARGET APPEAR. NOT THE TARGET, toss the float.
Do that from at least 4 directions and your target will be in the center of the floats.
It works great and the more you practice the better you get at knowing the unit you are using. Most cones from the units are 21 degrees. So figure on the view you see of the bottom is roughly one third of the depth. 100’ bottom you will be seeing a 30-40 feet circle.
Most of these units have a ZOOM feature in them. Once you see the target keep going over it while zooming in on it. You might be surprised at the picture you will get.
Good luck.
Gary D.
OP
PWCPD Diver
Guest
We now have side scan sonar on the boat to help narrow down the search area. The Potomac river is heavy with current, debris and zero visibility. This is why we usually use jack stays or fan searches.
I was just curious.
I was just curious.
We are still working on our SS. We take 10 steps forward and 3 back but at least we are still moving forward. We have a big chunk of the $$ for equipment already taken care of. Now it's just the 40K+ we need to get operational. Just pocket change for some.PWCPD Diver:
Gary D.
OP
PWCPD Diver
Guest
We used asset seizures to get ours and the boat. You guys could always solicit the feds for grants. We did that on some of our NVGs and thermal NVGs.
PaulSmithTek
Contributor
Coming from being a Commercial Diver. We use Line pulls and again walk back and forth then back 5' and back and forth and so on. We also use side scan sonar a lot, and if that isn't not available we use a fish finder. Worse case, we search by fanning out. Great times and a lot of great ideas and old techniques around.
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