An age-old question: ways to 60m.

[chillyinCanada]

Yes, but.........
"Rules are mostly made to be broken and are too often for the lazy to hide behind." (Gen. Douglas MacArthur) "Learn the rules so you know how to break them properly." (The Dalai Lama)

JFTR, the Dalai Lama did not say that

 

[Kay Dee]

JFTR, the Dalai Lama did not say that

And you know this, how?

 

[Boarderguy]

And you know this, how?

because she's the wizard from up north and knows everything. Keep pointing out her fallacies and she'll get her feels hurt

 

[Wheeler925]

And you know this, how?

I was there, I saw it

 

[crofrog]

Chamber if for treating decompression not narcosis. Chamber on site is when divers are on decompression schedules that go beyond the limiting line on decompression tables.

Consequently, whether you are on air, heliox, trimix, etc. If you are on a decompression schedule that goes beyond the limiting line on the tables, regardless of depth there has to be chamber on site at immediate notice.

It’s speaks to part of their overall risk mitigation. We have no operational need to go recreational (as in for fun) scuba diving. So picking and choosing the USN limitations and procedures in isolation from the rest of their protocols and procedures seems pretty fool hardy.

Which is clearly what you're doing when you talk about the operational limits of SCUBA in the context of air decompression diving...

The manual pretty clearly states "Closed-circuit underwater breathing apparatus is preferred over SCUBA for dives requiring decompression where a free swimming dive method is required."

Also clearly states that 130 is the normal working limit and that CO/OIC approval is needed to exceed that, I'm assuming they're only going to approve it when there is an operational need to take on the greater risk of exceeding the normal limits, and there is a strong need to do it on SCUBA vs surface supplied or using the EC-UBA.

 

[Kay Dee]

because she's the wizard from up north and knows everything. Keep pointing out her fallacies and she'll get her feels hurt

Well, maybe she knows something I don't on the 'issue' in question, and if so I'll change my tune re the DL being 'author' of said saying, should I be proved wrong.

 

[Kay Dee]

Also clearly states that 130 is the normal working limit

This be the USN for air, correct? RN was somewhat deeper (55m / 180ft?) IIRC, but maybe less these daze.

 

[old frogman]

Not enough info to answer this question in a general sense.

What are the location issues? Availability of help if something goes wrong (helicopter, chamber location). Weather and diving conditions. Type of boat. Conditions on the wreck. Expected slack period and currents. Target bottom and decompression times. Number of divers diving.

This week is a 70m/230ft wreck week in Malin Head, NW Ireland. The nine divers are all diving CCR on at least 14/50 trimix doing 1h30 to 2h30 runtimes. Helium for open circuit is NOT available. Nobody would be stupid enough to dive OC air, nor would they be allowed on the trip.

Your questions are too binary. Nobody would choose the inappropriate technology when far better technologies are available. This is borne out on the dive boats: there are very very few open circuit trimix divers seen on any dive boats for decompression diving. CCR is the most appropriate technology for diving beyond NDLs and especially below 45m/150ft.

Of course if you had to do a quick bounce dive in good conditions and only had air, then it is of course possible, but nobody would use that if better technologies are available.

My Dear Chap,

You wish to situate your point in NW Ireland, instead of Turkey. Cool. I agree. A 230 feet dive in the treacherous waters of NW Ireland on air would be an extreme risk.

Any marine activity around Ireland is risky. I recall the Fastnet yacht race in 1979. 303 yachts started, 24 abandoned, 5 sank, 15 sailors and 6 spectators died. Over 4,000 people were involved in the rescue. Winds reached Force 10-11 with waves up to 50 feet high.

I sincerely take my hat off to anyone who scuba dives there, regardless of gas choice. Ireland is Viking territory.

 

[old frogman]

It’s speaks to part of their overall risk mitigation. We have no operational need to go recreational (as in for fun) scuba diving. So picking and choosing the USN limitations and procedures in isolation from the rest of their protocols and procedures seems pretty fool hardy.

Which is clearly what you're doing when you talk about the operational limits of SCUBA in the context of air decompression diving...

The manual pretty clearly states "Closed-circuit underwater breathing apparatus is preferred over SCUBA for dives requiring decompression where a free swimming dive method is required."

Also clearly states that 130 is the normal working limit and that CO/OIC approval is needed to exceed that, I'm assuming they're only going to approve it when there is an operational need to take on the greater risk of exceeding the normal limits, and there is a strong need to do it on SCUBA vs surface supplied or using the EC-UBA.

Clearly you are a modernist rooted in the 20th Century of accepting the status quo. This is the 21st Century, the age of post modernism. Challenge everything and don't be timid about exploring the past. Medical researchers and Military researchers are constantly exploring past techniques for forgotten gems of knowledge.

Take the Romans. To quote Monty Python, "what have the Romans ever done for us?"

Back to the US Navy Diving Manual. The key point to take away is that air to 190 feet is doable according to "the book of knowledge". Yes, the US Navy does have caveats for enlisted personnel. I am not enlisted personnel. However, I will follow one caveat. Below 100 feet I will dive with 2 x cylinders. I am flexible on configuration, back mounted, side mounted, etc.

I recall advice from a Naval Diver Chief Petty Officer. The mark of a good diver is one that can adapt to any equipment presented to him (and her to be politically correct) and get the job done.

 

[inquis]

Deep diving on air must be approached with a strong sense of the possibilities of uncontrollable circumstances and negative outcomes...

There is no such thing as getting
“good” at deep diving on air. While a person may be truly competent, their competency will only allow them to be lucky when diving deep.

-- Wes Skiles, 1991