What is the largest and smallest floating metal flashlight?

EngrPaul · Dec 7, 2009

I recall reading an aluminum flashlight (Gerber?) would float if you use a lithium primary AA.

I got to thinking, is there any really small metal flashlights that float when loaded with cells?

Then I also started wondering, is there are any really big metal flashlights that float with power on board?

:shrug:

PeaceOfMind · Dec 7, 2009

Well, just as a data point, I can tell you that a Fenix LD10 with a Lithium primary AA (energizer) definitely does not float, and if you drop it in 6 feet of very cold water at night, you'll have to go in and get it

.

Dances with Flashlight · Dec 8, 2009

The Peak 2XAA Brass Caribbean could probably pick up enough speed descending into a watery abyss to drill very, very deep into the seabed floor.

Seriously, where would enough positive buoyancy be found in a metal flashlight? It would seem that only a flashlight with sufficiently great internal volume would have any chance at all of displacing more water than the light itself weighs. And if loaded, that internal volume would be occupied by batteries adding to total weight and further reducing any surplus of positive buoyancy.

Echo63 · Dec 8, 2009

these float
http://www.techass.com/el/elm4m/index.php

i believe the eveready dolphin models float too

LightCannon · Dec 8, 2009

Well, if you really need a light to float, I'd suggest tying a balloon to it (even better, a beachball.) and....yeah. lol.

elumen8 · Dec 8, 2009

Echo63 said:
these float
http://www.techass.com/el/elm4m/index.php

i believe the eveready dolphin models float too

The elitemarine and dolphin do float...unfortunately, the OP was asking for 'metal' lights that float.

And of course, I can't think of any small metal lights that float.

-JB

balou · Dec 8, 2009

It's rather hard to get a light to float.

For it to float, it has to be less dense than water.
Water: 1000kg/m³

Aluminum: 2700kg/m³
Magnesium: 1700kg/m³
Energizer AA Lithium: 1800kg/m³
Air: 1.2kg/m³

(all values are only approximative)

So the problem is: the lightest-weight metal commonly in use in flashlights, aluminum, is several times as dense as water. Magnesium, which could be used too, isn't that great either.
You'll have to counteract the weight of the flashlight and batteries with something lighter than water, and Air being the most obvious choice. There's air around the reflector, but not in any big quantities.

I'm randomly picking the Quark Mini AA. It's small, thus it has to be quite lightweight.

Mini AA dimensions (unfortunately, 4sevens uses non-SI based units, so there may be some error due to the conversion):

Weight: 19g
Diameter: 1.8cm
Length: 7.6cm

V=(d/2)²*pi*l
V=(0.009m)²*pi*0.076m
V=0.0000193m³

Density is defined as kg/m³
We get:
0.019kg/0.0000193m³
which gives just under 1000kg/m³

So, the Quark Mini AA will float!
Unfortunately, that's without batteries...

An Energizer AA Lithium weighs 14.5g, which would bring the total weight up to about 33.5g
0.0335kg/0.0000193m³ is about 1700kg/m³

With batteries it'll sink like a rock.

The conclusion? Seeing that such a tiny flashlight with minimal wall thickness will sink, the conclusion seems to be that you'd have to purpose-build a light with extra air tanks to bring the density under 1000kg/m³

Would be interesting to hear what Gerber light this rumor was about.

UnderTheWeepingMoon · Dec 8, 2009

The ones mentioned in this thread could be the largest.

LightCannon · Dec 8, 2009

balou said:
It's rather hard to get a light to float.

For it to float, it has to be less dense than water.
Water: 1000kg/m³

Aluminum: 2700kg/m³
Magnesium: 1700kg/m³
Energizer AA Lithium: 1800kg/m³
Air: 1.2kg/m³

(all values are only approximative)

So the problem is: the lightest-weight metal commonly in use in flashlights, aluminum, is several times as dense as water. Magnesium, which could be used too, isn't that great either.
You'll have to counteract the weight of the flashlight and batteries with something lighter than water, and Air being the most obvious choice. There's air around the reflector, but not in any big quantities.

I'm randomly picking the Quark Mini AA. It's small, thus it has to be quite lightweight.

Mini AA dimensions (unfortunately, 4sevens uses non-SI based units, so there may be some error due to the conversion):

Weight: 19g
Diameter: 1.8cm
Length: 7.6cm

V=(d/2)²*pi*l
V=(0.009m)²*pi*0.076m
V=0.0000193m³

Density is defined as kg/m³
We get:
0.019kg/0.0000193m³
which gives just under 1000kg/m³

So, the Quark Mini AA will float!
Unfortunately, that's without batteries...

An Energizer AA Lithium weighs 14.5g, which would bring the total weight up to about 33.5g
0.0335kg/0.0000193m³ is about 1700kg/m³
With batteries it'll sink like a rock.

The conclusion? Seeing that such a tiny flashlight with minimal wall thickness will sink, the conclusion seems to be that you'd have to purpose-build a light with extra air tanks to bring the density under 1000kg/m³

Would be interesting to hear what Gerber light this rumor was about.

Perhaps the IlluminaTi would have been a better choice: it's smaller, using an AAA battery, and lighter, as titanium, last time i checked, weighed less than aluminum (I might be wrong, since the last time I checked was...3rd grade.

)

But I hypothesize that it will sink.

^^Nova^^ · Dec 8, 2009

I remember being given a cheapo 2xAA incan haedlamp as a gift a few years back (before I found CPF) that had written on the front in large letters "floats in water". On the back, in really small writing, I found "only floats without batteries".

What use is it if it sinks when you are using it??? Marketing hype will add almost anything to the packaging if they think it will sell.

Cheers,
Nova

^^Nova^^ · Dec 8, 2009

Would a maglite float if you used those plastic AA>D adapters? The ones that replace a D cell with one AA instead. Should keep the weight down.

The McGizmo Ti lights don't float. Don has heaps of pics of them underwater and they are always on the bottom.

Cheers,
Nova

LightCannon · Dec 8, 2009

^^Nova^^ said:
I remember being given a cheapo 2xAA incan haedlamp as a gift a few years back (before I found CPF) that had written on the front in large letters "floats in water". On the back, in really small writing, I found "only floats without batteries".

What use is it if it sinks when you are using it??? Marketing hype will add almost anything to the packaging if they think it will sell.

Cheers,
Nova

I think this points out the problem with what the OP is asking for: Even if the light itself is light enough to float, the density and weight of the battery will cause it to sink (unless you have an extremely buoyant light.)

Th232 · Dec 8, 2009

LightCannon said:
Perhaps the IlluminaTi would have been a better choice: it's smaller, using an AAA battery, and lighter, as titanium, last time i checked, weighed less than aluminum (I might be wrong, since the last time I checked was...3rd grade. )

But I hypothesize that it will sink.

Umm... Ti has a higher strength to weight ratio, but is ~60% denser than Al, depending on whether you're looking at the pure metals or different alloys.

T0RN4D0 · Dec 8, 2009

Forget about floating small metal flashlights. You can though, tie anything that floats to and the whole thing will float under water

For the big floating lights... Probably there are lights that float without batteries... I'd be looking for batteries with thin walls and bad sinking... If they use D size cells, it may still float if you put in AA cells with light weight adaptors... I don't really know if there is such a light out there tho.

C-Beam · Dec 8, 2009

Maybe if you took a TK40 and used a 2 or 3 cr123 sub cell holder it would float.

LightCannon · Dec 8, 2009

Th232 said:
Umm... Ti has a higher strength to weight ratio, but is ~60% denser than Al, depending on whether you're looking at the pure metals or different alloys.

I stand corrected

balou · Dec 8, 2009

T0RN4D0 said:
Forget about floating small metal flashlights.

No I won't

^^Nova^^ said:
Would a maglite float if you used those plastic AA>D adapters? The ones that replace a D cell with one AA instead. Should keep the weight down.

That would be an interesting question. But... are Maglites waterproof?
edit: and Mag only states the weight of their lights with batteries.
So a 6D mag weighs 1417g - but that accurate-to-1g measurement is completely useless if they don't state with which cells they measured:thumbsdow

edit2:

a light with a diameter of 3cm and a length of 15cm, with a maximum weight of 55g would be able to float with an AA lithium cell.
considering that the Quark Mini is only 19g, and the heavier 1xAA lights are about 50g, a thinwalled aluminium light with those dimensions sounds possible.
Alloys like Magnalium (Aluminium+Magnesium) or Weldalite (Aluminium+Lithium). Magnalium (or at least one kind of magnalium) e.g. is only 2000kg/m³ in comparison to 2700kg/m³ of pure aluminium

Juggernaut · Dec 8, 2009

I can't see how any Maglite would float

oo:, I'm sure if I replaced the 18Ah SLA in my avatar picture light with 4x CR123s and sealed all the gaps in the head and the battery box, it would probably have enough buoyancy to keep a human from sinking, but it would be a stupidly inefficient light:shakehead.

Mjolnir · Dec 8, 2009

There is simply no way for a "small" flashlight to float and still look like a normal flashlight. No matter what it is made out of, the batteries will cause it to sink. If you wrapped a CR123 in aluminum foil, it would sink. "really small" means very low volume. It is possible to have a small metal cylinder float, but it would essentially have to be made out of aluminum foil. If you put ANY kind of battery in a light, it will not float. A small light is usually not much bigger than the battery, and you would need something MUCH larger than any kind of battery to enable it to displace enough water to cause the buoyant force to be greater than or equal to the gravitational force on the batteries.

Launch Mini · Dec 8, 2009

If you're concerned, go to a boat store, pick up those floaty key chains. They are on all boat keys.
Usually bright orange, so you can locate it easily.

What is the largest and smallest floating metal flashlight?

Flashlight Enthusiast

Enlightened

Flashlight Enthusiast

Flashlight Enthusiast

Enlightened

Enlightened

Enlightened

Enlightened

Enlightened

Enlightened

Enlightened

Enlightened

Flashlight Enthusiast

Enlightened

Newly Enlightened

Enlightened

Enlightened

Flashlight Enthusiast

Flashlight Enthusiast

Flashlight Enthusiast

Similar threads