Thoughts on how to recover a drone that went down in water with low visibility

[TxStig]

Is there enough metal that a magnet might be able to pick up on within the Mavic PP?

I had an aircraft that went down in a lake, I'd estimate the depth to be about 10 feet or so but the visibility in the lake is not great (I would estimate 1 - 2 foot visibility) & the bottom of the lake is very silty.

I was thinking about taking a 'Magnepull' & doing a little 'magnet' fishing with it, but I am not sure if it would pick up on the aircraft.

Thoughts?

Link to the Magnepull > https://www.amazon.com/MAGNEPULL-XP...1546607972&sr=8-5&keywords=magnetic+fish+tape

 

[Turbinewhine]

Sorry to hear about your loss.
I doubt there is enough ferrous material in the drone to lift it, especially if there is weeds on the bottom. You'd have better luck trying to snag it if you now the area it went down in. Otherwise it's time to don the mask and snorkel, find someone with a sensitive sonar system.

 

[Drone Or Boat]

I'll chime in on this one, only because I have a little experience on finding items on the floor of lakes. (lost a rod or two)
Like TURBINEWHINE said, not enough metal to do you any good. The question now becomes how much you want to spend on a drone thats probably shot now anyways. BUT, I have herd of a few stories where pilots have dried the thing out good enough to get some usable parts and maybe fly again. (with rice)
The problem here is, even 10 feet of water can be quite the challenge, even if you know the exact coordinates. Hopefully you have the GPS location numbers where it struck the water.
Next problem is, you need to search as much area of bottom with each swash of lake bottom that you can. Your 2 inch magnet idea will only place you looking for a drone with maybe 1.5' footprint searching for days. I suggest you make a simple device like this.

1. 3/4" PVC pipe 48" long.
2. 5- weighted treble hooks.
3. 60# test braided fishing line.
4. Small diameter rope.

Be sure to tie your treble hooks no longer than 6 inches. You don't want those things tangling up together. If you drag that thing along the bottom theres no telling what you may hook up on. You may catch some dead body. LOL
But with this, you can cover a 4 foot path each pass. This will give you a better chance at finding that drone.

 

[Mrmund]

Clam rake?

 

[gottahavit]

large fish net will have a 2 ft mouth and 6-8 ft handle that maybe you can extend?

 

[norman.hicks.35]

Ever thrown a cast net?

 

[coupevillecarpenter]

My lab can swim down 10 feet... she's pretty amazing!!!

 

[Jackcutrone]

Even with the last GPS coordinates it is hard to find something that falls on land in vegetation. My guess is that you won’t find it, sorry to say.

 

[TxStig]

Thanks for all the responses, I am only attempting a recovery as I have DJI refresh & they'll need the unit (of course non functional) to 'warranty' it out. As the days go by, I am losing more & more hope of recovery (wife factor \ dog house here I come ).

I know some folks that might be interested in scuba recovery, but in my previous attempts at the recover (tried attaching a large wading net i've used for flounder fishing to a 10 ft long PVS pipe) I've uncovered that the lake bottom is fairly silty so as the time extends I expect the silt to cover the unit up. I have very little familiarity with sonar \ fish finders so not sure of the benefits that one might have on locating anything on the lake bottom. Anyone have any thoughts??

Thank you again for all the responses. The funny thing in hind sight though is I've uncovered a couple of things out;

1) Getterback is not full proof (I became over confident on that being the ultimate tool to make sure that I could fly over water & be able to recover my drone).
2) Make sure you read & understand all instructions before becoming over confident on 'safety features'

 

[Jackcutrone]

On the fish finders I have used a silt bottom will show as somewhat lighter than a solid object which will be dark. However there may we’ll be other solid objects in the silt and differentiating them from your drone is going to be hard to impossible. If you go that route fishing stores sell small marker buoys that look like a dumbbell with line and weight attached that will unroll as the weight sinks. Lower one when you find something on the fish finder.

I have done some underwater recovery work and I am very doubtful that you will succeed. Even if you have GPS coordinates there are limitations to how precise they will be.

You can be almost right on top of something and easily miss it because it is a few feet off. It is almost impossible to maintain a precise search pattern with a small boat if there is any appreciable wind. When diving I use a heavy weight with a line attached and swim in circles around it paying out a little more line at the end of each circle. By this method you can be sure to cover the whole area.

I do wish you luck though. I hope I am wrong and you recover it.

 

[BD0G]

Is water Fresh Water? YES? Try and recover it
Is water Salt Water? YES ? Not worth time trouble and $
Is water Brackish? YES? Jump ball . Maybe worth the effort.

 

[crazyju]

We have a few locals that will dive for lost items for a small fee. One here will not charge anything if he doesnt recover. Maybe call a local dive shop?

 

[Turn11]

If you have any dive shops (Scuba) see if they have any "search and recovery" certified divers that might be interested. They are trained in searching by grid.

IF you aren't absolutely certain of the point where it hit the water, perhaps @sar104 could assist if you can post your flight log, Upload the log file from your display. Instructions below, then post the link back here. He has an uncanny ability to get very close to the crash site. Also he can determine what happened if you don't already know.

DJI Flight Log Viewer | Phantom Help

 

[AMann]

We made one of these to photograph invasive seaweed in a harbor- honestly, I could start a profitable underwater ROV rental business with some of you guys! Actually, my school made it so its not mine, but it was a rather easy project and could be used for recovering lost UAV’s:

DIY Submersible ROV

OP: you could use a simple weighted waterproof camera and a hook to do something similar. Sorry about the loss.

 

[tleedom]

Inexpensive underwater video camera

7" TFT Color Monitor 50M Fish Finder Underwater Fishing Video Camera 1000TVL | eBay

 

[AMann]

Maybe this will help- I think I should build a couple of these and start renting them out to some of you flying u-boat commanders-

Underwater DIY ROV’s: Homebuilt Rovs

 

[Drone Or Boat]

OK "TxStig", Did you get your drone back? It's been a month now.

 

[TxStig]

Still holding out hope, won't give up trying until after the dji refresh expires in May.

Nothing worse than knowing where it went down (within my reach at that as well ).

If I do recover I will definitely post up a response (I figure will also post up a response even if I don't recover).

 

[Drone Or Boat]

OK..... Did you try my idea? This is a proven way of recovering items on the bottom. (when you own a boat, you get creative)

 

[Turn11]

On the coast, hard to believe a dive shop doesn't have someone wanting to make a few extra $$