Rock Bottom/Turn Pressure/Rule of xths for Doubles?

[rstofer]

Well, that's what caused my husband to begin using the term "techreational" diving.

I do think that dives to the deeper recreational range (100 fsw +), especially in cold water, are dives where the core idea of technical diving -- solving problems underwater -- becomes more and more pertinent. Having redundancy, and facility with emergency procedures, gets more important the further you are from the surface. I still remember the woman who dove with us on the 600 foot walls in Indonesia, who was quite sure she could not replace and clear a kicked-off mask while in the water column. With no bottom beneath us, what was she going to do if someone descended on top of her, as happened to my husband?

In my mind, what a "deep" class should teach is not only about narcosis and hang tanks, but about mask skills in the water column, handling freeflows, and doing an air-sharing ascent under good control. It's a long way from 100 feet to the surface -- We had a fatality a couple of years ago, because two divers tried to execute an air-sharing ascent from that depth, and were unable to remain calm and controlled to the surface. People just underestimate the challenges of deep diving, in my opinion.

(Off my soapbox now . . . )

I totally agree! It's one thing to wander down a ways in clear warm water. It's another to do it in cold dark water with poor viz.

I have done a number of deeper dives in good conditions and it was never a big deal. I wouldn't even think of wreck penetration or cave diving without a lot more education. So, it won't happen...

One thing the NAUI program of yesteryear emphasized was buddy breathing. There is no reason in the world that an air-sharing ascent from any recreational depth should cause even the slightest concern regardless of the technique. My dive buddy, also of yesteryear, and I used to practice buddy breathing quite a bit. It was just something we did to pass the time. We'd breathe off our AIR II's, swap primaries, buddy breathe, whatever seemed interesting at the moment.

We never once came close to having to do it for real.

Richard

 

[Thalassamania]

Well, that's what caused my husband to begin using the term "techreational" diving.

I do think that dives to the deeper recreational range (100 fsw +), especially in cold water, are dives where the core idea of technical diving -- solving problems underwater -- becomes more and more pertinent. Having redundancy, and facility with emergency procedures, gets more important the further you are from the surface. I still remember the woman who dove with us on the 600 foot walls in Indonesia, who was quite sure she could not replace and clear a kicked-off mask while in the water column. With no bottom beneath us, what was she going to do if someone descended on top of her, as happened to my husband?

In my mind, what a "deep" class should teach is not only about narcosis and hang tanks, but about mask skills in the water column, handling freeflows, and doing an air-sharing ascent under good control. It's a long way from 100 feet to the surface -- We had a fatality a couple of years ago, because two divers tried to execute an air-sharing ascent from that depth, and were unable to remain calm and controlled to the surface. People just underestimate the challenges of deep diving, in my opinion.

(Off my soapbox now . . . )

I submit that the woman who could not replace her mask and divers that could not make an air sharing ascent either were either inadequately trained in the first place or, somehow either missed or neglected the material their class concerning practice and readiness. As far as 100 feet being, "a long way," that's only about a minute and a half with a continuously dropping _ppCO₂. I know that its a bugaboo for a lot of divers, but I'm here to tell you that with a little extra training a 100 foot ESE is not something to be overly concerned about.

 

[AndyNZ]

2. In many cases diving thirds is not conservative enough.

I'd agree with that. I like the idea of splitting your gas supply into "minimum gas" and "usable gas" portions, then doing applying thirds to the usable gas only. 1/3 of usable gas is your reserve, but should you need to eat into that reserve you've still got your minimum gas volume as contingency.

By what agency and which course? All tech divers would do something like this but recreational divers? PADI, NAUI SSI? ?A specialty course?

I like the term that was used earlier, "techreational"! I teach a PADI distinctive specialty course where multiple failures are introduced in a pool session to systematically task load student divers to help them understand their own limits and to decondition their panic response. Towards the end of the pool session, a typical skill combination would be an OOG diver & a lost mask donor doing a normal ascent whilst deploying an SMB. I don't really have fixed skill combinations, it depends very much on the individual divers involved what gets put together.

It doesn't really serve any real world purpose, but is a useful tool.

I would guess that many people teaching the SDI solo diver course may also do the same thing with multiple failures.

 

[texdiveguy]

"techreational"-- is a funny term considering for 99.0% of us on this board all our diving is simply recreational whether it is at 70ft or 300ft, on a reef in warm water or inside a wreck in the cold Great Lakes or following a gold line in a cave.

 

[Blackwood]

"techreational"-- is a funny term considering for 99.0% of us on this board all our diving is simply recreational whether it is at 70ft or 300ft, on a reef in warm water or inside a wreck in the cold Great Lakes or following a gold line in a cave.

Agreed. All dives done for recreation are recreational, regardless of depth/time.

Even using the word "technical" to describe dives often gives me pause, but I do it in keeping with the commonly understood jargon.

 

[rstofer]

Agreed. All dives done for recreation are recreational, regardless of depth/time.

Even using the word "technical" to describe dives often gives me pause, but I do it in keeping with the commonly understood jargon.

So a 300' deco dive is still recreational because it isn't done for profit?

I have always believed that a recreational dive was one in which the diver could make a direct, no-stop, ascent at any time. Any other type of dive was 'something else'. That definition would preclude any dives with mandatory deco stops, cave penetration, or wreck penetration. Among other things...

I suppose there are other definitions but that is the one I was taught.

Richard

 

[Rainer]

For me, a 300' deco dive done for fun (not pay or service) is definitely a recreational dive (as Tex and Blackwood note). I, and those I dive with, tend to avoid the term "technical diving". We just 'dive'.

 

[Reg Braithwaite]

I have always believed that a recreational dive was one in which the diver could make a direct, no-stop, ascent at any time. Any other type of dive was 'something else'.

Wandering afar, the rock climbing generally grades climbing on two main axes, the first is the technical difficulty of the climbing itself and the second is likelihood of injury or death should something go wrong.

This second factor is often called the "level of commitment." Soloing without a rope is obviously a very high level of commitment. In the 1960s and 1970s, big wall climbing in Yosemite was very committing, since the climbers themselves were the only ones with any expertise rescuing people.

Today there are certain alpine climbs where the climbers are essentially on their own. The younger generation often make "Fast and Light" ascents which involve continuous 30-40 hour pushes with short breaks, attempting to climb and descend a summit before a weather window closes. They are made with minimal gear, because the climbers believe that the weight and logistics of the "safety" gear actually slows the team down to the point where they are more vulnerable to weather.

Anyways, that's along, rambling way of saying that in another sport, the phrase "high level of commitment" seems to capture the principle of recreational diving that goes well beyond the big agency OW training.

 

[Doc Harry]

Your gas plan (Rock Bottom for the DIRs, we've always called it BINGO, after a similar aviation gas concept) should always get you and your buddy back to safety (surface, deco tanks, etc) and your buddy's should always get you back the same way.

Ha! I just started calling it BINGO gas myself for the same reason!

Great minds think alike.

 

[DA Aquamaster]

A few thoughts.

Planning and training for multiple failures is fine. It is pretty run of the mill cave training to practice a gas share while exiting lights out with touch contact. Actually getting to that point in the real world would require 3 light failures per buddy and a total OOA failure on someone's part. Still, it is good training and is a real confidence builder. And much of point of the excercise is to reinforce how much a failure of one type or another may slow you down - requiring a substnatial reserve.

When I said planning for multiple failures was not productive it was in reference to gas planning. It is common to plan for the loss of one deco gas, using contingency plans for back gas, the remaining deco gas and, depending on agency, the team's other resources. But you would not normally plan and equip yourself to lose both deco gasses and all your back gas.

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The term technical diving makes sense in same sense that the term technical climbing makes sense. In a technical climb the climber is having to make use of special equipment and/or techniques as opposed to some guy just hiking up to the top of a mountain.

Similarly, a cave dive, a wreck dive with penetration or perhaps just a deep dive 200' or so is in one sense just "diving" and is "recreational" in that you do it for fun, not money, but it is not really the type of diving a regular open water "recreational" diver can do with a great deal of expectation of surviving unharmed.

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As a pilot I like the "Bingo fuel" concept. It involves a lot more than just planning for x number of pounds or gallons of fuel in reserve - it takes into consideration all sorts of things like wind, weather conditions and available alternates in addition to a prudent and legally mandated reserve once you get to an alternate. In some cases, in some aircraft in some areas and conditions, you just don't go as you can't pack enough fuel into the aircraft to provide a sufficient reserve if the primary plan does not work out. In other cases, you may make a missed approach but then return to your starting poiint or divert rather than attempt another approach as you would fall below bingo fuel. It has definite applications in diving as it forces the diver to adequately plan and then just as importantly, stay well ahead of themselves during the entire dive.