zero visibility

[noob2]

i am sorry i was not to discriptive. When i ment zero visibility i mean when you put a gauge to your face you still can see any thing then how do you know when it is time to go up to the surface.

 

[Gary D.]

i am sorry i was not to discriptive. When i ment zero visibility i mean when you put a gauge to your face you still can see any thing then how do you know when it is time to go up to the surface.

If you are just down there trying to enjoy a dive and conditions are not going to improve rapidly the time to ascend is now.

If you have the training for zero vis operations and have a reason to be there fine. Other than that go play somewhere else much more fun and safer.

Gary D.

 

[Meng_Tze]

A true Braille dive is one where there is "black water", defined as water that has no light penetration. If you submerge the top of your mask it's DARK. The small layer of water between the faceplate and instrument lens formed by the instrument bump guard with the instrument pressed against the faceplate will absorb all light. Even a large light is useless.This is the world many commercial divers live in. When doing recoveries in some really nasty water back in the dark ages I had a mask with a plywood faceplate. If it gets dark before you get into the water the games your mind plays on you go down, and the last thing I wanted was to have that water touch my eyes from a broken faceplate due to bumping into something (before the days of tempered glass faceplates).

Almost all Braille dives are done to complete a specific task. Gary's will normally involve finding a car wreck or body, in the oil patch it's pipeline installation or repair, rig inspection, or any other construction or repair job. You eventually get to where you can "see" what's around you by feeling the little currents on your skin hair if diving wet and warm. My last black water dive was to recover some seismic source "guns" that had slipped their tether and buried themselves about 10' deep into the firm mud in the bottom of a fresh water test pond. The guns and controllers were worth close to 100K. The dive was cold and wet, but since nobody had EVER been in this pond I chose to do it in t-shirt and shorts so I could "see" a bit of what was around me. Gear was a J-valved single tank, single hose reg with no pressure gauge or octo to minimise possible entanglements. The recovery took about an hour once the gear and tenders and hoisting equipment were set up.

They were refilling that pond from a deep artesian well putting out water at about 40°F. Surface water wasn't bad, but the termocline, and black water started about 2' down. I thought I'd have to sit down to pee for a week!

FT

And thats where I draw the line......no way. FT, you are more man than I am.

 

[Lobbster]

i have been in zero vis, i was bring up the rear of a OW course to make sure no one got lost. i dont know if anyone has every swam behind 4 people doing there first real dive. i could see the start of there fins but not the straps or legs. it was messed up

 

[ibaun]

Did one of my first dives towards certification in near-zero vis water (no other option sometimes in Belgium, apart from Nemo33), and I must say it's not that bad after you get used to it. I was so happy to see that the vis was suddenly much better at -15m than it was at -8m.

 

[wreckchick]

i have been in zero vis, i was bring up the rear of a OW course to make sure no one got lost. i dont know if anyone has every swam behind 4 people doing there first real dive. i could see the start of there fins but not the straps or legs. it was messed up

Heck, to the commerical guys, that's fantastic vis!

To answer the question about how you know when you're ascending... listen to your ears. Mine tell me about depth changes of more than a foot or two.

Rachel

 

[Barracuda2]

...the only time divers should be attempting true zero viz or "black water" diving is when there is a job to be completed: vehicle or body recovery, searching for stolen articles for local authorities, repairing pond pumps, clearing debris from river or lake intakes, searching for artifacts or other "treasures", etc. They should be roped to an experienced tender on the surface and a team who are keeping time, and a fully geared stand-by diver ready to go in the event problems develop with main diver. Clear "pull" signals should be used to communicate from surface to diver and vice-versa. What in the world would be any other purpose for diving black water for recreational purposes??? I think it's just inviting a disastrous outcome. My $.02

 

[djb_1965]

I agree with Barracuda2. When we dive search and recovery in those conditions, It is foolish to not be tendered. Not only for reasons already listed, but there are always things on the bottom that can hang you up. With a tender there is always a line to follow down for a rescue diver. I do my sweeps with my eyes closed and go by feel, that way you are not trying to see the way, but relying on your tender. we are never down longer than 25 min, our policy. Even when training we have harness and ropes on to work on nav skills in zero vis. Nothing is worth dying for. There is pleasure diving and zero vis diving, and I separate the two.

 

[ianr33]

I have done a couple of dives in Travis where we came across genuine zero viz.Problem was it was only on the way up! Ascending from one dive there was a milky layer at the thermocline. Could not read my gages even with them and an HID pressed to my mask.As we were at around 100 feet and had some deco to do this was a little concerning. Went to touch contact and finger walked our way up the silt slope,it started to clear up after a few feet.

If you have to do a free ascent in zero viz from a deep dive then sending up a lift bag would seem to be the best option,although filling it and not getting entangled would be a challenge.

 

[LuigiD68918]

Oceanic DataMask. Worth every penny!