What is done when one “drags a lake”? You know, like when the police do it looking for a body or a car or something? I cannot imagine just how this works, and Googling “drag a lake” doesn’t help.
Do they literally drag a net or a scoop or something along the bottom? If so, how do they know they’ve caught something worth looking at? How do they know they’ve caught anything at all? Do they just dredge up everything and take a look at it and dump the boring stuff back in? Are there depth limitations? How sure are they that negative results aren’t false negatives? I’m sure many people know exactly how this works and can explain it in detail, but I’m sure not one of them.
You may have more luck searching under the term dredge. A lot of what you’re inquiring about technically falls under dredging–also, it may be that it’s mostly smaller bodies of water that are dragged, like ponds or wells or sections of small rivers.
You’re right, I might have more luck, but don’t you agree that dredging and dragging are not the same? Dredging is merely removing the bottom and moving it elsewhere. Dragging is performing some procedure or other – whatever it is – for the purpose of looking for something.
OK, Cheshire Human, what do these grappling hooks look like? Where can I find a picture of one? Have you done this yourself or read about it?
Either way, how do they know how deep to drop these grappling hooks? How do they know when they “snag something”? Can they just somehow tell by the tension on the line? How do they know it isn’t a rock or a log or a smallish alien spacecraft? How long does it take to drag, say, a one-acre pond?
I’ve seen it done in searches, and have done it myself using improvised equipment to look for things (not bodies) I’ve dropped overboard. They are three prong hooks coming out at 120 degrees from a central shaft. How deep is determined by dropping it in, and when it hits the bottom, the rope stops uncoiling. Then you pull along the bottom, until you feel thru the rope that the hook caught something. Then you pull it up and see what it is. How long it takes depends on how much crap is on the bottom that you have to check. I never stuck around long enough to get a good time estimate, and when I did it myself, I already had a good idea where what I dropped was, so it didn’t take long. For any more details, you will have to wait until a cop or firefighter who’s participated in a “dragging the river” search shows up to ask.
For where to find a picture, google image search “grappling hook” for a large variety of different types. I’ve only seen the 3 prong type.
There are devices to pull along the bottom, but divers are more commonly used when a specific location is searched because a human view is so much better. In that regard, high tech devices now view the bottom and eliminate the need for dragging.
When I worked at a Boy Scout summer camp as a rowing and canoeing instructor some 20 years ago, we had a “drag,” which was a thin but strong metal bar as long as my arm, with five wickedly-pointed hooks on it. If anyone had ever drowned in our not-so-deep but very murky lake and hadn’t been found otherwise, we were supposed to use that, towed behind a rowboat, to find the poor guy. Fortunately we never had to (I suspect local law enforcement would’ve done it for us anyway).
I’ve only seen it in movies. At the end of “Deliverance”, they show the guys throwing the grappling hook and dragging it along the bottom of the river.
Check out the movie, “The Gift” with Cate Blanchett and Keanu Reeves. There’s a grisly lake dragging scene that will very explicitly educate you on the procedure and the equipment involved.
