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

[dschonbrun]

I would tend to say that anytime you make the system more complicated than just a single first stage, you need more training... that's where "technical" begins for me. Even a bail out (which may contain a different mix) requires some knowledge... you have to know to crack it first... you have to know to inspect the MOD tag before breathing it...

All dives not for money are "recreational" I agree. But, I wouldn't allow an AOW, Nitrox certified diver to go on a fun dive while slinging doubles plus a Pony with 40% unless they had the "Tech" training to do so.

 

[imasinker]

I would tend to say that anytime you make the system more complicated than just a single first stage, you need more training... that's where "technical" begins for me. Even a bail out (which may contain a different mix) requires some knowledge... you have to know to crack it first... you have to know to inspect the MOD tag before breathing it...

All dives not for money are "recreational" I agree. But, I wouldn't allow an AOW, Nitrox certified diver to go on a fun dive while slinging doubles plus a Pony with 40% unless they had the "Tech" training to do so.

One person says diving to 300 feet is recreational, cave diving wreck penetration is technical, and another opinion that diving doubles you need to be "tech" trained. I am a new diver and maybe my opinion doesn't count or matter. There are so many different levels of dive training, yet I have not once seen anything defining where technical starts or recreational stops? Then I read the Wikipedia Article. again another idea of technical?

The concept and term 'technical diving' are both relatively recent advents,[1] although divers have been engaging in what is now commonly referred to as technical diving for decades. There is some level of professional disagreement as to what the term should encompass. Broadly, technical diving is any type of SCUBA that is considered higher risk than conventional recreational diving. However, some advocate that this should include penetration diving (as opposed to open-water diving), whereas others contend that pentrating overhead environments should be regarded as a separate type of diving. Others seek to define technical diving solely by reference to the use of decompression. Certain minority views contend that certain non-specific higher risk factors should cause diving to be classed as technical diving. Even those who agree on the broad definitions of technical diving may disagree on the precise boundaries between technical and recreational diving.

Webster defines technical as;

1 a: having special and usually practical knowledge especially of a mechanical or scientific subject <a technical consultant> b: marked by or characteristic of specialization
4: of or relating to technique

I only used two that seem to apply to what we are talking about here.

Recreational dives to me are dives within the recreational non decompression limits. Once a dive becomes a decompression dive outside the non decompression limits the standards change a hell of alot. I am not saying diving to 300 feet can't be done for recreational purposes, but your training is going to be more technical level due to higher risks, equipment and deco plans etc. That doesn't mean it can't be recreational. Gas mixures, stage/deco bottles, decompression stops and planing, the higher the risk of the dive, to me this becomes more technical in the training aspect. It just seems there are many opinions on whats technical and recreational to the new techreational. So I have come to the conclusion IMHO that I am a techreational diver. I dive to 120, I use doubles, drysuit, on a DIR style setup but no overhead enviornments, no deco bottles or stages all within the RDP. For now! I mean jesus i just started diving last year only logged 74 dives my first season and alot to learn I might add. Soon I will take the fundies, intro to tech ( theres that word again) maybe advanced nitrox deep diver, then maybe wreck penetration but I will always be a techreational diver.

TECH- for the advanced skills, special training required to dive such enviorments with higher risks requiring added equipment and life saving devices.
REATIONAL- because it will always be for fun.

This way I won't have to choose who to argue with about wheather I am recreational or technical regardless of where and how I dive.

 

[texdiveguy]

This way I won't have to choose who to argue with about wheather I am recreational or technical regardless of where and how I dive.

This silly topic of recreational diver or technical diver is not worth arguing over to anyone......if you are just out for fun and adventure and not engaged in commercial or military diving you are recreational regardless of your training or gear....it's really just that simple.

 

[Thalassamania]

This silly topic of recreational diver or technical diver is not worth arguing over to anyone......if you are just out for fun and adventure and not engaged in commercial or military diving you are recreational regardless of your training or gear....it's really just that simple.

OSHA recognizes three distinct forms of non-recreational diving: military, commercial and scientific.

Most "technical diving" is recreational.

As I've noted before: The concept of technical diving was derived from technical climbing. The analogy is in the requirement of reliance on gear to protect your life. In diving that means either a real or virtual ceiling that prevents direct access to the surface. Multiple gas mixes or rebreathers do not define technical diving, though most dives with either are technical dives however, but not all. All technical dives use SCUBA, surface supplied is something else altogether.

 

[nereas]

...The answer is, we live with the possibility that if a buddy goes OOA and we lose a tank, we don't have enough gas to get us both home. No problemo, question posed and answer given, I have zero editorial opinion about the answer.

That's all.

If you plan your dive so that you are completely buddy independent, then whatever happens to your buddy should not affect your dive.

Running OOA is a novice stunt. You would never expect such a thing on a technical-deco dive. Tank, bottle, or valve failure is the contingency you need to pre-plan for.

If a tank or reg fails, you simply isolate quickly, then shut down the valve.

If a valve on a tank fails, you simply isolate quickly.

Some agencies teach you to futz around with the valve before you isolate. But not all are that foolish.

If a deco bottle fails, you simply proceed with the last mix to the next gas switch, and reprogram your dive computer, or turn to another slate, or modify the in-your-head method you are using for deco.

Only after two such bottle failures in a row would I consider buddy breathing deco mix, thereby becoming buddy dependent.

If all your gear has been serviced annually, and you checked everything yourself carefully, listening for leaks, when you put it all together, a double-failure seems statistically improbable. Anything can break anytime, but two things breaking together is virtually impossible, if you are any kind of good diver who prepares properly.

When you take a tech-deco class, they will normally teach you how to think, and how to plan contingencies like that.

Rule of thirds works fine for me, on the back gas, and extra for the deco bottles as well. If you take a look at the specifics of the plan, and plan your tank sizes properly, you will see that there is plenty of gas for several contingencies:

250 FT 25 MINS TMX 15 / 55 +3 ALL EVENTS
4 DECO MIXES

V-Planner 3.43 by R. Hemingway, VPM code by Erik C. Baker.

Decompression model: VPM-B

DIVE PLAN #1
Surface interval = 5 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 3

Dec to 100ft (2) on Trimix 20.0/40.0, 50ft/min descent.
Dec to 250ft (4) on Trimix 15.0/55.0, 60ft/min descent.
Level 250ft 20:10 (25) on Trimix 15.0/55.0, 1.28 ppO2, 74ft ead, 94ft end
Asc to 190ft (27) on Trimix 15.0/55.0, -30ft/min ascent.
Asc to 180ft (27) on Trimix 20.0/40.0, -30ft/min ascent.
Stop at 180ft 0:40 (28) on Trimix 20.0/40.0, 1.29 ppO2, 75ft ead, 95ft end
Stop at 170ft 1:00 (29) on Trimix 20.0/40.0, 1.23 ppO2, 70ft ead, 89ft end
Stop at 160ft 1:00 (30) on Trimix 20.0/40.0, 1.17 ppO2, 65ft ead, 83ft end
Stop at 150ft 1:00 (31) on Trimix 20.0/40.0, 1.11 ppO2, 60ft ead, 77ft end
Stop at 140ft 1:00 (32) on Trimix 20.0/40.0, 1.05 ppO2, 55ft ead, 71ft end
Stop at 130ft 1:00 (33) on Trimix 30.0/30.0, 1.48 ppO2, 49ft ead, 81ft end
Stop at 120ft 1:00 (34) on Trimix 30.0/30.0, 1.39 ppO2, 44ft ead, 74ft end
Stop at 110ft 1:00 (35) on Trimix 30.0/30.0, 1.30 ppO2, 39ft ead, 67ft end
Stop at 100ft 2:00 (37) on Trimix 30.0/30.0, 1.21 ppO2, 34ft ead, 60ft end
Stop at 90ft 2:00 (39) on Trimix 30.0/30.0, 1.12 ppO2, 29ft ead, 53ft end
Stop at 80ft 4:00 (43) on Trimix 30.0/30.0, 1.03 ppO2, 24ft ead, 46ft end
Stop at 70ft 2:00 (45) on Nitrox 50.0, 1.56 ppO2, 32ft ead
Stop at 60ft 4:00 (49) on Nitrox 50.0, 1.41 ppO2, 26ft ead
Stop at 50ft 4:00 (53) on Nitrox 50.0, 1.26 ppO2, 20ft ead
Stop at 40ft 6:00 (59) on Nitrox 50.0, 1.10 ppO2, 13ft ead
Stop at 30ft 9:00 (68) on Nitrox 50.0, 0.95 ppO2, 7ft ead
Stop at 20ft 5:00 (73) on Oxygen, 1.60 ppO2, 0ft ead
Stop at 15ft 26:00 (99) on Oxygen, 1.45 ppO2, 0ft ead
Asc to sfc. (99) on Oxygen, -30ft/min ascent.

Off gassing starts at 199.6ft

OTU's this dive: 141
CNS Total: 61.9%

157.9 cu ft Trimix 15.0/55.0 [twin 120s or larger for rule of thirds]
17.2 cu ft Trimix 20.0/40.0 [these are all 40 cu ft bottles]
21.4 cu ft Trimix 30.0/30.0
28.9 cu ft Nitrox 50.0
23.0 cu ft Oxygen
248.3 cu ft TOTAL


Most divers would use two or three 80 cu ft deco tanks instead. I get better results with four 40s however. Either way, you have several possibilities to deal with several contingenies. Some people give me grief about my choice of 20/40, 30/30 together with EAN 50 and 100% O2. Whatever floats their boat is fine with me, I'll bring whatever I want.

Regarding how deep you can go into the wreck or cave, that will depend on the size of your twin tanks.

That's why its nice to have twin 130s.

 

[flareless]

If you plan your dive so that you are completely buddy independent, then whatever happens to your buddy should not affect your dive.

Damn, I spit coffee on my monitor when I read this and suddenly pictured an OOG diver ripping the reg from his unsuspecting buddy's mouth. Gave me a laugh!

Sorry.... proceed...

 

[texdiveguy]

OSHA recognizes three distinct forms of non-recreational diving: military, commercial and scientific.

Most "technical diving" is recreational.

As I've noted before: The concept of technical diving was derived from technical climbing. The analogy is in the requirement of reliance on gear to protect your life. In diving that means either a real or virtual ceiling that prevents direct access to the surface. Multiple gas mixes or rebreathers do not define technical diving, though most dives with either are technical dives however, but not all. All technical dives use SCUBA, surface supplied is something else altogether.

Oops I forgot the scientific group.........regardless it's still all recreational outside these 3 distinct groups. I don't think any true recreational-tech. diver thinks other.

 

[rjack321]

So are you saying that if we turn the dive at BINGO and then my buddy has a complete OOA, we do not have enough gas to get home if I subsequently lose one tank while sharing air with my buddy? To flip it around, if I lose one tank just as we reach BINGO, we obviously turn the dive on the spot. Are we now fuxxored if my buddy goes OOA on the way home?

Or is our BINGO plan to turn the dive while I have enough gas to handle losing one tank AND my buddy going OOA?

If you planned for simultaneous major failures of all the various major systems (gas/lights/line etc.) you'd rapidly realize you can't carry enough crapola and actually dive.

The reality is that equipment rarely fails and when it does its actually fairly easy to share and/or manage with a competent buddy or 2. Brain failures on technical dives are much more insidious and difficult to handle.

 

[J.R.]

This silly topic of recreational diver or technical diver is not worth arguing over to anyone......if you are just out for fun and adventure and not engaged in commercial or military diving you are recreational regardless of your training or gear....it's really just that simple.

Yup... but to call something 'technical' is *so* much more like buying a car that will go 200 mph. "Recreational" sounds so...ummm... *Prius*... or maybe even *KIA*... (One could make the arguement at ALL diving is, inherently, "technical" and that, like Olympic Diving or Gymnastics, the ONLY real separation is the 'degree of difficulty'... or perhaps "danger" apparently inherent...

... and then there's the ecconomic considerations.



Yep... if you don't do it for a living... it's "recreation"... if you do it for a living or if you're doing it for enjoyment in ADDITION to doing it professionally you're doing it as an "avocation"... if it's done purely to make a living (as a regular occupation)... we're talking "vocation" or an "occupation"... whew...

... one tank or two???

 

[nereas]

Damn, I spit coffee on my monitor when I read this and suddenly pictured an OOG diver ripping the reg from his unsuspecting buddy's mouth. Gave me a laugh!

Sorry.... proceed...

That would also be a novice stunt, and I have a rule that I don't dive with novices deeper than about 50 ft.