Reconsidering Deep Air?

[Marie13]

I start getting narced around 120ft. Mush brain really sets in around 130ft. There’s no way I’d do deeper diving without helium.

 

[helodriver87]

I was talking about people criticising relatively deep air dives but not the 800 foot dive described in the video posted by the OP If you’re using risk as a measuring stick the 800 foot dive on helium is a lot riskier than 187 feet on air

Because the 800ft dive is planned with the goal of minimizing risk wherever possible while still achieving the objective. The 187ft air dive isn't. You're conflating residual risk that can't be mitigated with unnecessary risk that is willingly accepted.

 

[Akimbo]

What adjustments can you make at 800 feet to minimise risk?

A saturation diving complex and a good crew. I locked out at just under 950'/290M nearly 50 years ago. We supported a team that locked out at 1,010'/308M about a month later. There have been thousands of man-hours in Sat at these depths without a loss of life.

hydrogen

I haven't seen HydrOx considered shallower than the 1,600'/500M range. I don't believe that Hydrox has been used since the Comex's demonstration lockouts at 2,300'/701M in 1992. Based on new sat systems being built, it looks like 400M is the consensus on where ROVs becomes more cost-effective than sat divers.

 

[Degenerate]

For me the maximum depth for air should remain 50 meters (164 feet), which is the limit written on my recreational certification (obtained in 1977). With a buddy, and doing deco using "back gas".

Maybe it's possible that the science has advanced a lot since 1977 and diving air to 50m is actually acknowledged as a bad idea now, even though you got certified to do it some 40+ years ago...?
Hell I don't even dive air to 30m in our local quarries as they are pitch black at that depth and around 4 degrees celsius, it's nitrox down to 30m and deeper than that it's trimix for me.

 

[tursiops]

Maybe it's possible that the science has advanced a lot since 1977 and diving air to 50m is actually acknowledged as a bad idea now, even though you got certified to do it some 40+ years ago...?
Hell I don't even dive air to 30m in our local quarries as they are pitch black at that depth and around 4 degrees celsius, it's nitrox down to 30m and deeper than that it's trimix for me.

Both the science and the technology have advanced considerably, but it is indeed remarkable how many folks cling to what they learned and used way back when, or to what they were taught not so long ago by someone who was stuck with old knowledge. For example, "don't ascend faster than 60 ft/min" is still around, due to this cling-to-the-past effect, likely exacerbated by liability concerns and possible embarrassment. Or turning the gas back a quarter turn. or mask-on-forehead means panic.

 

[Akimbo]

For example, "don't ascend faster than 60 ft/s" is still around

Of course it is because it is still true. 30'/min isn't faster than 60'/min.

I do miss 60'/min. Following those small bubbles was a lot easier without a downline than staring at your computer nag at you to speed up or slow down. I have yet to find a 30'/min bubble.

 

[grf88]

"For example, "don't ascend faster than 60 ft/s" is still around,"
That is about 41 mph, that is quite some DPV.

 

[rjack321]

Both the science and the technology have advanced considerably, but it is indeed remarkable how many folks cling to what they learned and used way back when, or to what they were taught not so long ago by someone who was stuck with old knowledge. For example, "don't ascend faster than 60 ft/s" is still around, due to this cling-to-the-past effect, likely exacerbated by liability concerns and possible embarrassment. Or turning the gas back a quarter turn. or mask-on-forehead means panic.

Acclimation to narcosis was debunked at least a decade ago, maybe more now, but it's regurgitated again. I guess its just part of the circle of scuba life on the internets like these other hard to kill myths.

 

[tursiops]

Of course it is because it is still true. 30'/min isn't faster than 60'/min.

I do miss 60'/min. Following those small bubbles was a lot easier without a downline than staring at your computer nag at you to speed up or slow down. I have yet to find a 30'/min bubble.

And, it is old and outdated knowledge that your bubbles rise at 60 ft/s. Some go faster, some go slower. It is size dependent, and the size changes as they rise.

 

[tursiops]

"For example, "don't ascend faster than 60 ft/s" is still around,"
That is about 41 mph, that is quite some DPV.

oops. thanks, edited.