After 8 days at 80 feet in the cold waters of Puget Sound

[Letac]

Hi there,

Just wanted to share some photos of my Mavic 2 Pro that I crashed a while ago. After shooting some footage for an hour, I was feet away from landing. As I was coming around a large boat, I pushed a stick by accident and slammed into the dock. It was a cold November day and my hands were freezing. That clearly contributed.

Anyway, I lost an hour of work and that was the last day of good weather for a while. For days I pondered what to do, and on day 8 I called a diver shop and had them dive in in hope that if they located it, I could perhaps recover my footage. Before they dove in they told me the chances were slim and that currents had likely carried it to the middle of Puget Sound. Fifteen minutes later they found it. It sat at the depth of 80 feet for 8 days. And most importantly, I recovered every single file from my SanDisk card, rated to survive several hours at 10 ft. The plastic at the bottom of the drone that's missing did not brake upon impact. It's the salt that ate through it.

Hope you don't go through this

 

[dougga]

Thanks for sharing. Very cool that the SD Card still worked.

 

[TonyPHX]

Well, at least you have something to send in. Sent to DJI and get a quote at least.

 

[Yorkshire_Pud]

The plastic at the bottom of the drone that's missing did not brake upon impact. It's the salt that ate through it.

It's not plastic, it's a light weight metal of some sort.
I am pretty convinced that the majority of the corrosions stems from a 'cell' being set up between the steel of any screws and these light weight metals.
If you open the drone I think you will find the innards are equally destroyed. In the wreck I bought the frame that carries the rear and sideways looking sensors no longer existed, it was mush.
I stripped the wreck for plastic body parts, nothing else was salvageable.

I am glad you salvaged the video.

 

[GFields]

Sorry for your loss, but glad you were able to retrieve your footage

 

[DougMcC]

Thanks for the photo documentation. Amazing what can be destroyed in a mere 8 days in salt water. Your card manufacturer might enjoy your tale and pictures.

 

[MAvic_South_Oz]

The plastic at the bottom of the drone that's missing did not brake upon impact. It's the salt that ate through it.

It's not plastic, it's a light weight metal of some sort.

I'd guess aluminium (or aluminum for our US readers), it certainly gets corroded fast in salt water (galvanic corrosion), but that eaten away like that is quite amazing.
Of course it would be very thin material.

 

[AMann]

Put it in a bag of rice and it’ll be like new in a day or two!

Wow- so what chewed up the edges? I’ve seen fish nibbling on stuff, maybe some bottom feeders like a halibut?

 

[MS Coast]

Put it in a bag of rice and it’ll be like new in a day or two!

Wow- so what chewed up the edges? I’ve seen fish nibbling on stuff, maybe some bottom feeders like a halibut?

Rice is not a magic solution.

Check some references on that. I think the only positives you'll find for rice as a desiccant will be on Facebook, Twitter, and such. The only reference I was able to find that suggested it was a group dealing with hearing aids in the remote areas of a third-world country.

A warm dry airstream and chemical desiccant packs can be effective for moisture removal. A few weeks ago, we resurrected a nice Sony zoom lens that had been dunked in clean fresh water by blowing warm air over it for four days and then the better part of a week in a jar with several desiccant packs.

Saltwater is really rough to deal with. Moisture is much less a problem than corrosion.

 

[Starz]

Put it in a bag of rice

Waste of good rice.

 

[AMann]

Rice is not a magic solution.

Check some references on that. I think the only positives you'll find for rice as a desiccant will be on Facebook, Twitter, and such. The only reference I was able to find that suggested it was a group dealing with hearing aids in the remote areas of a third-world country.

A warm dry airstream and chemical desiccant packs can be effective for moisture removal. A few weeks ago, we resurrected a nice Sony zoom lens that had been dunked in clean fresh water by blowing warm air over it for four days and then the better part of a week in a jar with several desiccant packs.

Saltwater is really rough to deal with. Moisture is much less a problem than corrosion.

I really just meant it as a joke, as putting it in a bag of rice seems to be everyone’s panacea for trying to get wet valuables dry. Silica gel packs made for electronic equipment lockers that can be regenerated are one of the best desiccants you can buy, but I think that Mavic is a little bit beyond drying out!

 

[BroomRider]

I'd guess aluminium (or aluminum for our US readers), it certainly gets corroded fast in salt water (galvanic corrosion), but that eaten away like that is quite amazing.
Of course it would be very thin material.

If it's a lightweight alloy, such as Magnesium, that would be even worse.

Magnesium is highly reactive, depending on the alloy & the environment. What might work great as a lightweight structure for a drone, might not tolerate prolonged submersion in an electrolytic solution (salt water) well.

Depending on the interior structure of the drone, whether that part was in proximity to, & especially if, it had any electrical connection to the battery, the corrosion in salt water would be greatly accelerated in comparison to aluminum.

Magnesium is generally a superior alternative to aluminum for aircraft, being roughly 2/3 the weight of aluminum & with better strength to weight ratio; I wouldn't be surprised if DJI used a magnesium alloy in the manufacture of that part.

I know from experience working in the marine service field, sacrificial anodes were frequently made from magnesium due to their greater reactivity in salt water, which provided better protection for the part to which they were attached.

As for the effect to any metal in salt water, the corrosion is greatly increased when placed in the proximity of an electrical source, especially, if it is connected to it.

A devious prank on, or means to secretly attack, a boat at a mooring or dock, would be to take a fully-charged lead-acid vehicle-type battery, & drop it into the water just under the boat. The electric field generated around the battery would extend outward in a “halo” & begin to corrode any metal parts below the waterline in a greatly accelerated rate, with no indication as to why unless someone were to dive looking for it.

I suspect that the part was made of a magnesium alloy, & that the battery supplied the electrical field, resulting in a similar effect, despite only being submerged for 8 days.

I'm sorry for the loss of your drone.

In an aside, Pro-Tip: don't piss-off your marine service technician!

 

[MS Coast]

I really just meant it as a joke, as putting it in a bag of rice seems to be everyone’s panacea for trying to get wet valuables dry. Silica gel packs made for electronic equipment lockers that can be regenerated are one of the best desiccants you can buy, but I think that Mavic is a little bit beyond drying out!

We're on the same page then. Humor doesn't always come across in forums like this, does it? And there are people around who firmly believe that rice is the best cure for drowned electronics.

Yep, that Mavic is definitely beyond hope. I hope it didn't sound like I was suggesting that hot air and desiccants could put it back in the air.

 

[MAvic_South_Oz]

I suspect that the part was made of a magnesium alloy

There are many alloys with good drone friendly advantages.
I figured aluminium generally being less than half the cost of magnesium might play a factor in DJIs choice.
Most manufacturing companies will weight up a lot of factors for components, quality, lightest, easiest to work with, etc, but price is often the biggest consideration they will be focussed on.
It looks like aluminium around what’s visible on the corroded edges, not sure whether magnesium would also have that light silver colour.

 

[lookout]

Rice is not a magic solution.

Check some references on that. I think the only positives you'll find for rice as a desiccant will be on Facebook, Twitter, and such. The only reference I was able to find that suggested it was a group dealing with hearing aids in the remote areas of a third-world country.

A warm dry airstream and chemical desiccant packs can be effective for moisture removal. A few weeks ago, we resurrected a nice Sony zoom lens that had been dunked in clean fresh water by blowing warm air over it for four days and then the better part of a week in a jar with several desiccant packs.

Saltwater is really rough to deal with. Moisture is much less a problem than corrosion.

I did recover a smart phone that way it did work. But I dropped something in the drink the other day, but because it was warm and low humidity environment, It was good to go before I got home. I didn't have a chance to get home and rice bag it, but now I didn't need to.

 

[BroomRider]

We're on the same page then. Humor doesn't always come across in forums like this, does it? And there are people around who firmly believe that rice is the best cure for drowned electronics.

Yep, that Mavic is definitely beyond hope. I hope it didn't sound like I was suggesting that hot air and desiccants could put it back in the air.

Oh, I think that drone is going back into the air…

On wings, on its way to Drone Heaven!

 

[Frank Dracman]

Put it in a bag of rice and it’ll be like new in a day or two!

Wow- so what chewed up the edges? I’ve seen fish nibbling on stuff, maybe some bottom feeders like a halibut?

I was going to suggest duct tape but I thought MS Coast might take it seriously

 

[MS Coast]

I was going to suggest duct tape but I thought MS Coast might take it seriously

As long as he uses the blue marine-grade duct tape, it should be just fine.

 

[dennish]

Rice is good to fill your belly but not for drone drying after salt water immersion. It only takes seconds of immersion to ruin a mavic. I speak from bitter experience.

 

[RangerEd]

It's not plastic, it's a light weight metal of some sort.
I am pretty convinced that the majority of the corrosions stems from a 'cell' being set up between the steel of any screws and these light weight metals.
If you open the drone I think you will find the innards are equally destroyed. In the wreck I bought the frame that carries the rear and sideways looking sensors no longer existed, it was mush.
I stripped the wreck for plastic body parts, nothing else was salvageable.

I am glad you salvaged the video.

I was thinking, how could salt water eat through plastic? Having metal in there makes sense.