Any small torch can be used under water.

Any small torch can easily be used under water ... For example , the iTP A2 will run for two hours on maximum and seven hours on medium ... Switch the light on immediately before you dive , put the torch into a small glass Sauce bottle or similar with the LED facing down and screw the lid on ... As long as the glass bottle is small enough to grip easily , it will work OK ... And with the lid screwed on tightly , it is waterproof.

I wouldn't like to use this method on a high power torch because of the lack of heat transfer.
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Good idea.

A ziplock bag also works pretty well.

Chauncey Gardner said:

Good idea.

A ziplock bag also works pretty well.

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Just how deep have you been using this method?

Has anybody actually tried diving with a standard flashlight? Any success stories or were they all miserable failures??

Till you go more than a few meters down and the glass bottle implodes under pressure and slices your hand up.

gcbryan said:

Just how deep have you been using this method?

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It sure sounds safer than expecting some random soda glass bottle not made to withstand pressure to do so without shattering in your hand.

Jay R said:

Till you go more than a few meters down and the glass bottle implodes under pressure and slices your hand up.

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Prevent it by filling it with water...

oh, wait!

But you could fill it with isopropanol or something non conductive

Presumably, a resistored twistie could be used without any enclosure at all, as all components are themselves sealed and the low voltages and currents involved aren't bothered by water. Remember to take it apart when you're done and let everything dry in the shade. If it was used in saltwater, wash its components with clean water first.

It occurs to me that you could actually make the flashlight a lot more powerful, as water is much better at sinking heat than air.

Would a glass bottle really implode at a few metres? I'd have thought you'd have to go pretty deep for that to happen. Maybe this is why so few distress messages in bottles never make it to the shore.

Depends widely on the thickness and structure of the bottle. I'd expect small, thick-walled bottles for alcoholics to survive to a decent depth; larger jars with thin walls would implode a lot sooner.

Zatoichi said:

Would a glass bottle really implode at a few metres? I'd have thought you'd have to go pretty deep for that to happen. Maybe this is why so few distress messages in bottles never make it to the shore.

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True, about 10m down the pressure is about 2 atm, compared to the 1atm inside the bottle this isnt very much of a pressure difference......

If you want to go really - i mean REALLY - deep you could consider one of those 'Keep2Go' (or any normal pet blank) things if you have a light to fit in there... I dare anyone here to dive deep enough to implode one of those I bet you 1 whole dollar that it will start to leak way before it 'implodes'.


And if you're not going too deep, you could also just throw a condom around the light and tie a knot in the end, just don't expect a good beam profile :devil: Works great for cellphones too, calling your mates from under water is great fun!

At 100 feet the differential between the outside and the inside of the bottle would be 43.5 psi. or 3 atmospheres.

Most/many bottles could take that. It depends on how thick they are. If the glass lens on a dive light can take it so can a bottle.

I'm guessing that a ziplock will not keep water out beyond a few feet.

As far as most flashlights making it...it depends. A reverse clicky will turn off and you won't be able to turn it back on at a certain point. Beyond that it will leak as well. A twisty with decent o-rings in many cases will go to 100 feet or so (I've done it).

The front lens needs to be sealed with more than the stock o-ring in most cases. The glass lens is too thin to go much beyond that.

Regarding letting your flashlight flood...that's ridiculous. In freshwater (with a led) you might be able to get away with that for a while if you're lucky and the batteries don't leak.

In saltwater low current circuits will short out (the driver that is). A higher current circuit often can handle it (as in an accidental flood) but you don't get many second chances.

Water is good at conducing heat but practically speaking we are talking about keeping the inside dry and having good heatsinking and having water take away the heat after it is transfered to the outer body. If you do that you will get higher output for a longer period than you would on land.

If you think low current circuits aren't bothered by saltwater try turning your cell phone on and dropping it in saltwater.

A messy solution is to fill the flashlight with mineral oil. The circuits will be OK and water pressure will not be an issue as long as the light is completely filled. Changing batteries is messy and the optical output may be effected.

For a quick, emergency dive light, it's not hard to convert many lights but it usually makes more sense to just buy a cheap dive light unless you've picked the right host and correctly modify it.

Pöbel said:

Prevent it by filling it with water...

oh, wait!

But you could fill it with isopropanol or something non conductive

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Pure water is nonconductive.

Another way is use an industrial WD40 type product,spray the entire torch in the product and it should work underwater easy enough.We use to spray mains light bulbs in our product and immerse in water and then switch the light on,worked fine but health and safety issues stops us now from doing this demo.

Jay R said:

I see it this way, a large jam jar is about 70 square inches. 1 atmosphere is around 6.3kg per square inch. 70x6.3= 441.00

Now, would you want to hold a piece of glass in your hand that's being subjected to 441kg of pressure ? ( Over 1,000 pounds for you imperial mesurers.)

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No way under the sun would I

try a miniq 40 its a dive torch ..or search for dive torches. the led sl6 by underwater kineticks is pritty good.land torches dont realy work under water...been there seen it ..didnt work. better to buy something build for the job

march.brown said:

Any small torch can easily be used under water ... For example , the iTP A2 will run for two hours on maximum and seven hours on medium ... Switch the light on immediately before you dive , put the torch into a small glass Sauce bottle or similar with the LED facing down and screw the lid on ... As long as the glass bottle is small enough to grip easily , it will work OK ... And with the lid screwed on tightly , it is waterproof.

I wouldn't like to use this method on a high power torch because of the lack of heat transfer.
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Click to expand...

I inadvertantly dropped a pair of secateurs (pruners) into a five foot deep water-butt ... I wanted to grab the secateurs with a long pair of barbecue tongs but couldn't see what to grab ... I tried shining a torch in but it was no good ... I made up my waterproof housing from a narrow sauce bottle as the iTP A2 was able to fit through the neck of the bottle ... I screwed the lid on and attatched a piece of cord to the neck of the bottle and added a bit of sticky tape (just in case) then lowered my light five feet into the water ...

And there was light ....

I was able to retrieve my secateurs easily , though my arm got wet as the tongs were not long enough.

So there we are ... It was safe up to five feet.
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At REI once I bought a princeton tech headlamp that claimed it was waterproof down to 200 feet. I went snorkeling and don't think I ever went past 10' deep and it leaked.
They swapped it as they always do with no hassle. The new one went out on the first use in water - I was taking a shower in Honduras - there were no lights. I got another one - the exact same one only they had changed the label/packaging to say it was now waterproof down to 1000' (who takes their light 1000' down... I suppose if it could do 15'000 feet someone could use it to duct tape/silicone the oil leak out in the gulf.) That one didn't survive its first bath in the ocean.

My point - very few products can do what they say they can. It's nice when testing that to know you got it at a store with a hassle free return policy. I did still complain heavily to REI though as the product they represented was so far from what it claimed; it wrecked my plans - looking forward to driving to the beach and night snorkeling. Then I still had to make 6 trips to the store...

Ok, I'm missing something. Wouldn't someone who can afford fancy expensive diving gear also be able to afford a suitable diving light and NOT need cheap and clumsy DIY waterproofing techniques? If I missed the whole point that this is simply an exercise in hypothetical thinking and that I've ruined the whole thing, them please forgive me in advance.