Thoughts on Bounce Dives

[Akimbo]

Lol, I don't need those certifications...

I wouldn't be surprised if you could get an ASME/PVHO chamber for less than today's material cost, especially one that has been fully depreciated (tax-wise) already -- probably several times by different companies. The advantage of putting the same money into an ASME/PVHO double-lock is eventual resale or expanding into using the chamber for an income stream... like training. Otherwise it is scrap-iron after you are done with it. Chambers have not changed much in 40 years since PVHO was published. Typical rust allowance is 1/16" and avoid dents. Even stripped NPT penetrators are usually repairable.

A new un-outfitted double lock was less than $5K in the late-1970s

 

[Superlyte27]

Thanks!

 

[kensuf]

Was deep air ever taught? Learning to dive deep (a highly relative term) on air on Scuba is a very long and labor intensive process of self-discovery. Unfortunately, the basic physics and physiology required for the journey has been divided into half a dozen separate classes.

level 6 is a thrill ride.300 Multiple Choices

Management

PSAI Narcosis Management® training, the best in the world, has you perform only the underwater skills that relate to the actual real world of diving, keeping up with Depth, Air, Time and Awareness (DATA). You must become comfortable and competent with the mental and motor skills at each training depth before training down to the next level. The training you receive in this course, which covers equipment selection and configuration, dive planning and gas management, buddy awareness and dive execution is applicable to all levels of diving. Any diver, regardless of certification level from Open Water through mixed gas closed circuit rebreather will benefit from this course. PSAI is the only agency offering Deep Air training awareness down to 73 meters ~ (240 feet) taught in six levels. There are currently only ten instructors world wide qualified to teach to level VI.Level I 30m (100') Level II 40m (130') Level III 46m (150')Level IV 55m (180') Level V 61m (200') Level VI 73m (240')

 

[Hawkwood]

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A ScubaBoard Staff Message...

Hey folks, this is an update to Boulderjohn’s two Mod Posts. I deleted a Post “credited” to NWGratefuldiver that was not in fact, posted by him.

Nothing nefarious…it turned out that a Moderator hit the “edit” button rather than the “reply” button while viewing his Post. That resulted in his text being in NWGratefuldiver's Post. I also edited a couple of posts that referred to that now deleted post. It took a while to figure this out.

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[C Dub]

Did you really do the rigs to 250 on air, with the bottom at....600 feet?

Resurrecting my own Deep Air/Dark Narc encounter to 80m on Oil Rig Eureka here in offshore SoCal a year ago, in 12deg C water temp depth at the time. Used double AL 11L manifolded cylinders, an AL 11L tank of Oxygen, a drysuit for exposure & redundant buoyancy, and a DPV Scooter.

Planned dive was a quick powered scooter descent to 90m for a few minutes, and then multi-level profile up with most of the time spent at 18m, with O2 deco at 6m as needed. Total Dive Time was 50min, with deco obligation cleared before 12m (per Petrel Computer on 30/85 GF), but I did a few minutes on O2 at 6m anyway for a cleaner inert N2 purge.

With the scooter off and stowed, all it took was three frog kicks into the current at 80m depth, and I was instantly overcome with a narcotic CO2 hit: Hyperventilation & difficulty breathing the regulator, high density & flow viscosity of the Air mix & resulting Hypercapnia came on immediately. In the dim ambient light, the only thing I was able to perceive was my Petrel Computer flashing an extreme PPO2 Warning prompt of 1.9, and it took a few minutes focused concentration not to panic , just to hang onto a support beam and try to regain a nominal breathing rate & clear head before starting the ascent using the scooter. (Note: Elevated CO2 also increases the likelihood of hyperoxic seizures.) Not at all pleasant and I don't want to do that again. . .

The point is that a Deep Air bounce dive like above can be treacherous even if planned and prepared as a technical dive . . .It would be absolute suicide to attempt this recreationally only on a Single Tank!

 

[LiteHedded]

JOhn,
Thanks for the article....
It actually gives credence to what I had always suspected, that if you are going to deep drops, you need long surface intervals between them....that just because some freedivers are capable of doing a 3 minute or more drop, than a 3 minute surface internal or LESS, and then going back down for another deep drop, is NO reason to actually do it. It makes total sense that you will begin to grow bubbles, or "seeds" with each deep drop.....which gets the whole issue looking more like a scuba diver that is not using long enough surface intervals...or that has some bubbling going on, and then on the SI, decides to do a couple of deep drop freedives between scuba dives.


I think if this ever gets studied in depth, there will be very large differences between "some" individuals and the "average" individuals....suggesting there may one day be some genetic markers for people with some of the mammalian genes which are far more utilized by seals or dolphins. Without going on too far of a tangent, in the late 70's to the early 90's, I did a great deal of diving with the First diver and dive operation owner of Palm Beach---Living dive legend Frank Hammett( was scuba diving Palm beach from around 1955--about a year after when Gagnon invented the Aqua Lung) ....Even into his 60's, Frank could dive the Hole in the Wall on a single al 80 ( depth to 135 feet), shoot fish till he ran OOA....Free ascend to surface, grab another tank, then immediately go back down and shoot till OOA again. I do not believe Frank EVER felt the need to visit a chamber....that he was ever bent enough to know it--or at all. He remains mentally sharp to this day, and in his 60's he was still the fastest swimming diver I had ever met.

Beyond Frank Hammett, George Irvine of the WKPP had/has an ability to off-gas at a level far off the charts when compared to the Us Navy Tables. This led to George and Bill Mee and Dr Bill Hamilton, developing "Special" trimix tables for George to use on 6 hour long bottom time dives at depths averaging 280 feet deep. Deco for this for George would be around 11 or 12 hours--far from the prediction of the Navy tables, and the successful use of these tables by George and JJ and other WKPP members led to Navy Spec Warfare, being onsite for many of the big dives George and JJ did.

George's personal tables were extended for use by others, using VO2 max...a measure that correlated well to overall perfusion and adaptations to intense cardiovascular training, and others would have a multiplier from VO2 max shift their personal tables to the appropriate degree of less aggressive off-gassing, based on the assumptions from their correlated perfusion....
I was, and still am, able to use George's tables today, for 100 foot to 300 foot dives, without any change for Vo2 max--as George and I were close...mine being a bit higher than his in the 90's. He was a competitive Masters Swimmer, I was a racing cyclist ..both require intense peripheral adaptation to training. We assume this is responsible for the faster off-gassing schedules that the WKPP tables utilize.

Point being....for freediving, I see there is powerful evidence now that a form of tables needs to be developed...and that behaviors need to follow this.

I will likely be doing more deep freediving in the near future, due to some of the opportunities in diving I now have, so I plan on looking in to this a great deal more closely...
Having Bill Mee as a dive buddy and close friend, also means I will have him working on some form of table development for my freedivng

---------- Post added October 19th, 2015 at 09:43 AM ----------

*** Notes on this
I am not a fan of "tables for everyone"...I was able to see in the WKPP tables, that George could actually make a tech dive safer for him and me, using his schedule, than the dive would have been for us using the Navy Tables...( or the present PADI or GUE tables)...So I do think some factor needs to customize any new table, to the individual.

Tables like what PADI uses are a very bad start of any new science on this, as they include fudge factors such as poor cardio fitness, as well as fudge factors to deal with the 25% of the population that has a PFO--this being a group which obviously needs to be EXCLUDED for the purposes of finding and ideal set of tables for an individual without medical problems.

If ever someone is able to find a genetic Marker for this mammalian gene that makes the person able to off-gas so far from the general distribution as to make no sense whatsoever ( call this the Hammett Gene , then this needs to be recognized, and far more doppler and other studies need to be done on each of these people, with hopes of gaining insights as to what types of off-gassing schedules they could actually use.

wkpp isn't using any fancy special 'fast off-gassing tables'

that's old George era stuff

 

[danvolker]

wkpp isn't using any fancy special 'fast off-gassing tables'

that's old George era stuff

I did say "George tables"...which to me, is better. It worked for me in extreme scenarios, and I have no intention to change because of a new regime

 

[LiteHedded]

I did say "George tables"...which to me, is better. It worked for me in extreme scenarios, and I have no intention to change because of a new regime

I don't think that's why the change was made.

Some of that old stuff just doesn't hold water. Like a 240 deco gas after a 280' dive.
Air 190 deco gas etc. things change over time as we learn more about what works and what doesnt

 

[danvolker]

I don't think that's why the change was made.

Some of that old stuff just doesn't hold water. Like a 240 deco gas after a 280' dive.
Air 190 deco gas etc. things change over time as we learn more about what works and what doesnt

What you refer to must have been in vogue long before what Bill, George, and I were using from 96 on.
That was NEVER part of anything I saw or heard of.
All I am saying, is since I did many hundreds of 250 to 300 foot dives, using George tables, with zero dcs, and requiring much less gas than current WKPP tables, I would not consider throwing out what works for me, for what might NOT work as well for my physiology. Bill Mee feels the same way.

 

[Kevrumbo]

Did you really do the rigs to 250 on air, with the bottom at....600 feet?

To reiterate (and getting this thread back on track):

The point is that a Deep Air bounce dive can be treacherous enough even if reasonably planned and prepared as a solo twinset technical dive with the aid of a scooter above . . .On single tank however, any emergent contingency at depth will most likely result in tragedy. . .

The infamous & creepy tragedy of Yuri Lipsky who recorded his own demise:

https://m.youtube.com/watch?v=cRj0lymMMGs

The Cozumel 90m Bounce Dive Tragedy:

cozumel accident 9/4/11, THE FACTS