theorectical pressure question ....

[Silver_2000]

Ok Im going Scuba Diving in a few weeks and am looking for options for storing gear that Im unwilling to leave on shore and unable to leave in hotel room - Im considering buying a dive light - leave the batteries out and storing the gear in the light. The gear is sensitive to both pressure and water AND is expensive.

So here is the question - If the light is watertight at depth to say 30 meters that means that no water enters. What happens to the pressure in the sealed container ? If you use a submarine as an example a sealed sub stays at basically 1 bar when it descends and it requires no pressurization.

So can the same thing be said for the interior of the light ? what is the likely percent increase in pressure at depth ....
Im assuming if the shell of the light maintains its dimensions and no water gets in then the pressure inside should remain the same ....

there are some smart people here .... What do you think ?

I could spend $225 and get the cool looking mcmurdo dive canister
http://www.starmarinedepot.com/smd/images/prodimages/mcmurdo/IMC1500-10_L.jpg

looks to be over kill though

[dboat]

I believe your logic is correct.. however, if you were to take the device to lower depths, the device would initially deform (creating greater internal pressures) or implode, defeating the purpose of the device. The question is how strong is the device and will it deform under 30 meters of water? if so, how much and also, the equipment that you have is also able to withstand some change in pressure as well, I assume. Do you know if it can handle 1.5 bars or more?

Dana

[Mark #2]

I say for ~$200 buy something that is designed for the job.
Your assumptions are correct, but the risk $$$ and potential loss for it's operation are too great for the savings. IMHO.

[Moonshine]

I would defer to our resident engineers, Mark and Bob. With that in mind, I believe your logic is accurate. The concern I'd have is whether the light depends on having the batteries installed to help maintain it's structural integrity at depth. Absent deformation/implosion of the light shell, I believe the interior pressure would remain at 1 bar.

[Silver_2000]

I would defer to our resident engineers, Mark and Bob. With that in mind, I believe your logic is accurate. The concern I'd have is whether the light depends on having the batteries installed to help maintain it's structural integrity at depth. Absent deformation/implosion of the light shell, I believe the interior pressure would remain at 1 bar.


Hadnt considered that ---- HMMM

Thanks - Il have a pool to use for 15 foot testing - trying to justify the 200 canister but its been tough

[Mark #2]

Just FYI, my watch is good to 330 ft and it is a very simple O-ring seal.
How big is the stuff and does the storage unit need to sink or float?
PVC with screw on end caps, read sprinkler system parts, easily withstands 4 bar.
Another thought, a simple air compressor filter container is good to 7 bar, just an O ring.
I would guess Tupperware is good to 15 feet.

[L8 APEX]

Most recreational diving is above 100ft that is only 3.5 times pressure, I assume your gear would be safe above that. If you are speaking of electronics a concern of mine would be condensation if the water got cold enough vs the surface temp, the Caribbean should not be a problem though.

[Sixpipes]

Doug disqualified me from this thread when he wanted to ask the smart people stuff. But I do know my Tupperware.

My advice? Get the dive canister. No one would ever suspect that you might be a computer nerd if you were seen caring it. Tupperware would be a dead give away.

It's all about image these days and $225 is a relatively inexpensive way to show others that you really got it going on. :cool:

[98Cobra]

No way would I believe having the batteries installed matters. If so, you are basically saying that the light would begin to experience crush pressure and deform, only to be hopefully saved by your not-Chinese battery's structural integrity? I can't imagine its designed that way.

[Silver_2000]

No way would I believe having the batteries installed matters. If so, you are basically saying that the light would begin to experience crush pressure and deform, only to be hopefully saved by your not-Chinese battery's structural integrity? I can't imagine its designed that way.
I looked at 2 dive lights today and the springs ETC that keep the batterys in contact would be crushed against the batteries as well - - I think that Garrett is right - BUT it is a concern I hadnt considered.

[L8 APEX]

It must not take much to protect electronics... I saw these bags at a dive shop this weekend.
http://drycase.com/

[Silver_2000]

It must not take much to protect electronics... I saw these bags at a dive shop this weekend.
http://drycase.com/

Thats a solution for the water problem - its the pressure thats also a problem - since Ill be protecting an insulin pump the pressure changes will at least screw up the insulin in he cartridge - Ironically the pump is waterproof - The attached BG meter is not but I can remove that.


waterproof IPX8, Unlimited surface swimming, 8 feet for 30 minutes

I havent yet purchased a $250 aluminum canister but I might ... Im still hoping a Underwater light will work - havent found one I like that was significantly cheaper than the canister

[99bolt]

Are you shore diving or boat diving? If diving from the shore, I can understand not wanting to leave thingslying around so they can walk off. If boat diving, can you not leave the things in your bag on the boat.

Most rec diving is less than a 100', so the pressures aren't that great. I have seen a flashlight deform from pressure when the batteries weren't installed. Most lights will be fine at the pressures you're loking at though.

If you have to take things diving with you, I would suggest double bagging to be safe. Find a hard container that will suffice, then put that inside one of them vinyl dry bags. If you want to be stress free, go ahead and buy the expensive container and have fun.

[Silver_2000]

Are you shore diving or boat diving? If diving from the shore, I can understand not wanting to leave thingslying around so they can walk off. If boat diving, can you not leave the things in your bag on the boat.

Most rec diving is less than a 100', so the pressures aren't that great. I have seen a flashlight deform from pressure when the batteries weren't installed. Most lights will be fine at the pressures you're loking at though.

If you have to take things diving with you, I would suggest double bagging to be safe. Find a hard container that will suffice, then put that inside one of them vinyl dry bags. If you want to be stress free, go ahead and buy the expensive container and have fun.
Yep its the shore diving - Yoiu just pull up to a Yellow rock with a name on it and walk in to the surf.

Boat diving is easy - just leave it in the shade on the boat -- Maybe even something like this will work since there is no way we will be going near 100meters
http://www.opticsplanet.net/s3-t4000-waterproof-dry-protective-cases.html

http://kayak-ekipirovka.com/upload/20110602/pic663457-1.jpg

[Moonshine]

I have seen a flashlight deform from pressure when the batteries weren't installed.

Thank you! It just makes sense that the batteries would help prevent outer shell deformation. Is it easier to crush an empty beer can or a full beer can?

[dboat]

Thank you! It just makes sense that the batteries would help prevent outer shell deformation. Is it easier to crush an empty beer can or a full beer can?

Full beer can.. because I am motivated to get the juice that is inside of it to go inside of me!!:D

Dana

[99bolt]

Yep its the shore diving - Yoiu just pull up to a Yellow rock with a name on it and walk in to the surf.

Boat diving is easy - just leave it in the shade on the boat -- Maybe even something like this will work since there is no way we will be going near 100meters
http://www.opticsplanet.net/s3-t4000-waterproof-dry-protective-cases.html

http://kayak-ekipirovka.com/upload/20110602/pic663457-1.jpg

Sounds like fun, its been a few years since I've been rec diving.

That should work if you don't mind the bouyancy it will add.

[Silver_2000]

Sounds like fun, its been a few years since I've been rec diving.

That should work if you don't mind the bouyancy it will add.

it looks bigger here than it is... smaller than some dive lights


Outside Dimensions (inches):5.89 x 3.74 x 3.16Ill line it with lead if need be ...:evil