
Lifeguards use a drone to help rescue people in danger of drowning - lnguyen
https://www.businessinsider.com.au/video-lifesavers-used-a-drone-to-help-rescue-two-people-in-danger-of-drowning-in-heavy-surf-2018-1
======
aynsof
I was out in the surf off the NSW coast today, and it was scary as hell.
Massive waves that suck you in and spin you around like a washing machine,
coupled with a strong current pulling you out to deep water.

I definitely would have felt safer knowing there was a drone in the sky above
me, ready to drop a flotation device on me. Our lifesavers do a great job, but
it's a long, long way from the beach out to a drowning swimmer.

~~~
pbhjpbhj
You could tow a floatation device anyway, then the drone doesn't even need to
work.

It's there a "pocket-sized" buoyancy aid that locks into a small canister you
can strap to your wrist/ankle? I'd guess not due to insurance liabilities.

~~~
TheSpiceIsLife
> It's there a "pocket-sized" buoyancy aid that locks into a small canister
> you can strap to your wrist/ankle?

Yes, yes there is. It straps to your wrist and uses a CO2 canister like the
ones used to inflate bicycle tyres: [https://www.amazon.com/Kingii-
Lightweight-Wearable-Portable-...](https://www.amazon.com/Kingii-Lightweight-
Wearable-Portable-Recreational/dp/B019YT2DZM)

------
mentos
From the headline I thought a high powered drone lowered a line for the
swimmer to be lifted out of the water.

[https://www.youtube.com/watch?v=At3xcj-
pTjg](https://www.youtube.com/watch?v=At3xcj-pTjg)

Casey Neistat worked with a team to create a drone capable of lifting him and
his snowboard in heavy ski gear/boots. I bet you could make something like
this to lift a drowning swimmer to the beach.

~~~
falcolas
One of the hurdles is that the traditional multi-rotor design doesn't scale up
well. The blades just gain too much mass to be quickly sped up and slowed
down. As the craft gets bigger to hold bigger payloads, more energy has to be
devoted to fighting rotor momentum, making them less efficient.

It's why most multirotors over a certain size use variable pitch rotors, like
a helicopter. And at some point, the complexity of managing multiple variable-
pitch rotors just makes the single rotor design of a helicopter more
efficient; especially when it can be powered by a gas engine.

Of course, a normal helicopter can be run remotely just as effectively as a
multi-rotor.

~~~
goldenkey
When you say 'gain more mass,' do you mean the inertia from the rotor speed? I
would think the more rotors you have, the slower each can spin? Is it possible
there is an efficient design we havent yet tried involving self-stabilizing
bearings or ball detents?

[https://en.m.wikipedia.org/wiki/Ball_detent](https://en.m.wikipedia.org/wiki/Ball_detent)

~~~
falcolas
Intertia from both mass and speed (larger props tend to spin more slowly, at
least in part to keep the tips sub-sonic).

Traditional multi-rotors, like the one featured in this article, maneuver by
quickly changing the speed of the props with respect to the other props to
change the attitude of the craft. The larger the prop, and thus the greater
the inertia, the harder it is to quickly change the rotational velocity of
those rotors.

Which is why helicopters tend to use variable pitch props, since they can
alter the lift (and rotational force) generated by the prop without having to
change the velocity. Well, that and variable pitch props let you create
differential lift (such as tilting the helicopter into forward flight) with a
single rotor as well. :)

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bamboozled
Honest question, how does this thing work in conjunction with rough seas and
high winds? Weighted perhaps ?

That looked like a relatively calm day but that's rare, especially coupled
with rough seas.

Don't like conspiracies but that almost looked to good to be true.

~~~
falcolas
Multi-rotors of that size can handle some pretty serious winds (10-15 ish
MPH+, more if you're willing to potentially lose it to save a life). And since
the craft itself isn't in the water, it doesn't have to deal with the seas.

~~~
JoeAltmaier
Seas are often not flat. The wave height and spray can easily be a threat to a
drone.

~~~
falcolas
Indeed. But from the picture on the site, it looks like they were about 150
feet above the average sea level. It would take quite the rogue wave to hit
the drone at that altitude.

Sea spray (fine droplets of salt water) would indeed have an effect, but more
over the long term than immediate problems since the motors are brushless.
Brushless motors are not terribly susceptible to shorts from water, and the
only other vulnerable component - the battery - would be hard to short out by
sea spray alone.

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nartz
Very cool - although hard to tell from the video that they were in danger.

~~~
owenmarshall
If you don’t know what to look for, it’s very easy to miss someone _right
beside you_ :

[http://www.slate.com/articles/health_and_science/family/2013...](http://www.slate.com/articles/health_and_science/family/2013/06/rescuing_drowning_children_how_to_know_when_someone_is_in_trouble_in_the.html)

> To get an idea of just how quiet and undramatic from the surface drowning
> can be, consider this: It is the No. 2 cause of accidental death in
> children, ages 15 and under (just behind vehicle accidents)—of the
> approximately 750 children who will drown next year, about 375 of them will
> do so within 25 yards of a parent or other adult.

~~~
Harvey-Specter
> 375 of them will do so within 25 yards of a parent or other adult.

This stat always rubs me the wrong way. It paints the image of a parent
watching their child drown, but I imagine it's pretty easy to be within 25
yards of the pool and have no visibility to the pool.

~~~
tqkxzugoaupvwqr
I don’t think it is meant to imply parents purposefully watch their kids
drown. It is more of a warning that drowning isn’t obvious and can be silent.
You might lay next to the pool and think you could rescue your kid at anytime,
it is just a couple of meters away. But your kid may never shout for help
because it is struggling to breath and stay afloat.

I watched a video of a life guard jumping into a large crowded pool, swimming
towards a certain location. Even though I knew somebody is drowning there, my
untrained eyes couldn’t spot the drowning person until the life guard almost
reached the child. Everyone next to the child was completely oblivious and
looked funny at the lifeguard wondering why he is swimming towards them.

~~~
lfowles
I think this was posted to HN a few years back:
[http://spotthedrowningchild.com/](http://spotthedrowningchild.com/)

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mleonhard
> Deputy Premier John Barilaro said the investment had already paid for itself
> with the “world first rescue”.

A company in Iran developed a lifeguard drone called Pars, in 2013:
[http://www.bbc.com/news/technology-24929924](http://www.bbc.com/news/technology-24929924)

I couldn't find any information about the Pars drone being used in a rescue.

------
smoyer
I'm glad the boys are safe! This is something that was bound to happen
eventually and we've seen recent videos of this use and many others in
advertising. I think dropping floats from a some is a natural use but it will
be interesting to see if some of the other ideas survive.

~~~
celticninja
Some larger drones could easily drop a rope with a handle and pull them to
safety.

~~~
lostapathy
I'm not sure we're there, yet, today.

Yes, I've seen the video where Casey Neistat hangs off a drone in ski gear.
But to attempt a rescue, the drone is pulling against somebody who isn't
trained (more movement means harder to stabilize). You're also fighting
against the ocean, so you're going to need extra power to pull the person
against the waves, at least until you get them plucked out.

As mentioned elsewhere in this thread, the drone will need to operate quite a
bit higher up to stay safely clear of water and heavy spray, so the person
would be at the end of a much longer rope, and a longer rope means the system
is a longer "pendulum", which again means it'll take more energy to stabilize
it.

An ocean rescue is going to happen on a warm day, whereas the Casey Neistat
video was done in cold, dense air where drones are more efficient.

I would not be surprised if it takes an order of magnitude more energy, at the
drone, to pull a person out of the ocean that it takes to lift a calm person
on dry land. That's a big hill to climb.

