SNUBA ice diving

[oldflounder]

I was just curious if anyone has tried SNUBA through a hole. Would keeping the tank topside in a warm bin of water prevent freeflows? I am not recommending this as a way to ice dive. I can just see a possible application in situations such as doing a vehicle recovery in shallow [5 - 8'] of water where you can almost stand up but you must get underwater to do the hookups. Not having a tank on would also help maneuverability[sp?] around the vehicle under there. Of course you would still have a small pony attached/hung somewhere. This might also be applicable to doing repairs on circulation pumps at the docks/ship/etc. I am not talking recreational diving here.

 

[Akimbo]

Surface supplied is pretty common in Public Safety diving, often including hard-wire communications and FFMs (Full Face Masks). The actual supply may be all high pressure cylinders or a combination of HP storage and a LP compressor.

 

[tbone1004]

hookah is better than snuba, but it is possible and done regularly.

 

[Rich Keller]

Surface supplied diving under the ice would be safer then scuba. I would dive with at least a full size tank if not doubles though. I would gear up exactly the same as if this were just a scuba dive and you would have the additional air and communication with the surface. Keeping the tank warm would probably not help though. By the time the air gets to the diver after going through a cold hose it will make little to no difference.

 

[Subcooled]

There are three types of free flows:

1) the unavoidable: exhaled air is humid, so humidity accumulates in the single hose regulator second stage even if you wouldnt allow it to fill with water. If the water is cold then the second stage will freeze. This may take a long time but sooner or later it will happen. It may be annoying to not be able to feather the valve (located above the ice) in this situation.

2) deserved: The second stage free flow happens faster if you pour snow in the mouth piece, or if you get the stupid idea to protect the mouth piece with a plastic bag (I did)(it traps warm moist air, and when you bring the bagged regulator out, it will get wet and freeze)

3) the avoidable: first stage free flow: moisture in the tanks. Bad compressor (make sure that the water removal function works), water in the cylinder (pour it out), snow in the cylinder valve or first stage (assemble the kit indoors)...

And finally, a free flow turns your regulator from a demand valve into a constant flow valve. Hint: that black rubber knob on the cylinder really does control the amount of flow. Either manual on-off, or a nice mouthfull every 10 secs. Your choice.

 

[Akimbo]

Commercial divers that normally operate under ice usually use hot water heated wetsuits. Some of the hot water is tapped off to heat the second stage regulator and sometimes the breathing gas. It is very difficult to prevent moisture freezing in the second sage because LP compressors don’t output air as dry, dives tend to be much longer, and it isn’t practical to be as careful handling equipment on deck.

Hot water suits are also favored because it is very difficult to protect drysuits from tears and punctures in heavy working environments. About 2½ gallons/minute of 110° F hot water is supplied to the suit through a manifold. Rubber tubes with holes punched about every 4" distributes hot water throughout the suit. Each tube terminates at an open end at both hands and feet, plus one for the hood.

 

[DivemasterDennis]

I.ve seen this a bunch on the tv show about gold mining in the Bering sea and Alaska. Does not look fun.