Safe distance above water

[scro]

Not that it answers "how low above water is safe" but would not one way of testing the range of the sensors etc. be to take off on a significant slope and go high, well over the 30m. Then, staying well above 30m AGL, fly either up slope or down slope until lthe ground directly beneath the drone is either significantly higher or significantly lower than the home point. Then descend vertically at maximum speed and see where, AG, the drone starts to automatically slow its descent. I presume the drone does not know the height of the ground relative to the take off point so it must be measuring or be attempting to measure it's height AGL during the descent if not the entire flight .
I can't test this myself here, sorry.

@PhiliusFoggg I tried this this morning. Full speed descent in sports mode from about 30m height - around 3m from the ground the drone slows its descent gradually down to zero, stopping about 0.5m above the ground, before initiating landing.

 

[Deleted member 103366]

Was that with the landing point well above or well below the take off point etc. ?

 

[scro]

There wasn't much height variation in the local terrain so it was difficult. Looking back at the log I was about 2m higher than the initial takeoff point for the test.

 

[scro]

Went flying over some sand dunes this afternoon, and tried again at 14m below takeoff point. Exactly the same behaviour, with the drone slowing descent at about 3m above the landing point.

 

[BokiFly]

I tried this this morning. Full speed descent in sports mode from about 30m height - around 3m from the ground the drone slows its descent gradually down to zero, stopping about 0.5m above the ground, before initiating landing.

So it will not crash if descent even in full speed? Interesting to know.
I suppose that is the work from the bottom sensors (no matter is it below or above takeoff point).

 

[Deleted member 103366]

In situations like the purely vertical descent it seems safe but I wouldn't absolutely rely on it and if there is horizontal movement.....
Also be aware that attempts to fly very low seem to trigger automated landing behaviour and at 50cm or less (over land) you might not have time to abort the landing.

 

[marcorasi1960]

I really do not understand this discussion. I fly very low over water all the time. I am talking so low that I see the water moving from the propellers wind. I do this to photograph birds and alligators. I have gone as close to the water as the drone allowed me to at least a hundred times. My Mavic 2 Zoom never tried to land. As long as I don't keep pushing down on the left stick, the drone refuses to go TOO close to the water. Have I just been lucky?!?

 

[scro]

I guess the water you're flying over is fairly turbid if it has alligators in it? If so it has plenty of suspended solids in it to reflect the IR beam from the sensors. Clear water doesn't reflect IR light as well so can easily confuse the IR sensor.

 

[EyesWideShut]

I really do not understand this discussion. I fly very low over water all the time. I am talking so low that I see the water moving from the propellers wind. I do this to photograph birds and alligators. I have gone as close to the water as the drone allowed me to at least a hundred times. My Mavic 2 Zoom never tried to land. As long as I don't keep pushing down on the left stick, the drone refuses to go TOO close to the water. Have I just been lucky?!?

It may be safe for your Mavic 2 Zoom. The OP is talking about the Mavic Mini which has lots of threads on flying with caution over water/snow.

 

[BokiFly]

I fly very low over water all the time. I am talking so low that I see the water moving from the propellers wind. I do this to photograph birds and alligators.

I would like to see some of your videos/pictures

 

[scro]

The MP2 zoom has 2 downward facing obstacle avoidance cameras compared to just 1 on the Mini. With 2 you can have depth perception as well as motion, so it's not surprising it flies better in close proximity to water.