Not diving to greater than 30m/100ft unless with helium

[Kevrumbo]

Or eliminate the risk entirely and just don’t go there. It’s not like recreational divers (which includes the vast majority of technical divers) are being paid or have a job to do.

There’s always something deeper we “would like to see”, but there is nothing that we “need” to see. “Would like to see” isn’t worth exceeding your limits to have a little fun. Find, set, and stick by your limits. Sure there is a gray area, but that is why you need to slowly and carefully find your limits over time rather than just arbitrarily accepting some else’s.

Well it's not arbitrarily accepting other people's limits per se ....as non-professional/non-commercial/non-military, "sport" technical divers, you learn your own limits through a lot of trial & error -and learn through the mistakes of others.

 

[Akimbo]

Well it's not arbitrarily accepting other people's limits per se ....as non-professional/non-commercial/non-military, "sport" technical divers, you learn your own limits through a lot of trial & error -and learn through the mistakes of others.

I should have been clearer. I used your quote as a backdrop for my comment relating to the original question rather than to counterpoint your quoted message.

I think that learning limits is the same process for military/commercial divers as everyone else except the time scale is compressed -- more time in the water/year, chamber dives, and longer training. What goes on in the diver’s head is about the same for both in order to discover our limits.

OK, my "Or eliminate the risk entirely and just don’t go there" comment is probably a reflection a commercial diver’s more mercenary point of view. Heck, a lot of guys won’t even get their suit out of the bag without being on the clock.

 

[MXGratefulDiver]

Well it's not arbitrarily accepting other people's limits per se ....as non-professional/non-commercial/non-military, "sport" technical divers, you learn your own limits through a lot of trial & error -and learn through the mistakes of others.

... or learn through the mistakes of self ... I've had my share of "I'll never do that again" moments, the key is leaving yourself enough safety margin to survive them ...

... Bob (Grateful Diver)

 

[Kevrumbo]

Another example of CO2 retention on Deep Air causing headache:

I have noticed a painful and somewhat recent development in diving with air to depths below 100'. I recently returned from Truk and all of the dives were between 100' and 170'. Helium is not common on the island so I was diving air or EAN 30%. I would develop the headaches about half way through the dives. No one else experienced the headaches, so bad air may be ruled out. This is not the first time this has happened, but this was the most recent. The headaches usually go away a couple of hours after the dive. I drank no alcohol and had plenty of water.

At those depths, increased work of breathing begins to become significant. One of the big advantages of He mixes is reduced viscosity and easier flow. If you mixed the increased work of breathing with any exertion underwater (current?) it would be easy to imagine some CO2 retention, and one of the major symptoms of that is headache.

I actually got my first taste of CO2 retention headache diving in the caves in Florida recently. Diving against heavy flow is a lot of work, and I didn't adjust my breathing, and ended up feeling pretty horrible with a bad headache and nausea post-dive. It was a powerful incentive to fix the problem.

Having just done Ginnie Springs on 30/30 for the first time, I can enthusiastically and with complete conviction report that, for me, the answer is YES [compared to Nitrox 32 at 30m/100']. Not only do I remember more than a vague, dark gestalt of the cave, but I came out for the very first time ever without a pounding, horrible headache and nausea. It was a totally different dive.

http://www.scubaboard.com/forums/te...se-dive-trimix-single-tank-3.html#post6344078

Thanks for everyones info. . . I did not consider CO2 retention, but now it seems pretty obvious. I guess it would only make sense, because my dives have gotten deeper and deeper. I think I have reached my limit on air.

http://www.scubaboard.com/forums/ask-dr-decompression/212601-headaches-diving.html

How Deep is Too Deep?

 

[MXGratefulDiver]

As someone who did many dives with Lynne ... including deep dives ... I am going to refute the speculation. Lynne's susceptibility to narcosis was about average. She did have some issues with disorientation in mid-water, but as with all things she worked on that till she got it under control. I think what may have led to the misimpression was her above average attention to safety margins ... Lynne was an extremely cautious diver, and carefully followed a regimen that gave her as much control over her options as possible. This had more to do with her personality, and her training as a doctor, than it did anything to do with narcosis. In effect, she didn't follow the 100-foot rule because she was overly susceptible to narcosis ... she did so simply because she thought it was a good idea.

... Bob (Grateful Diver)

 

[Kevrumbo]

http://www.scubaboard.com/forums/te...se-dive-trimix-single-tank-3.html#post6344078


This post would seem to refute this idea. She indicates here that she was unable to do a good job at even REMEMBERING a 100 ft dive.

This degree of narcosis susceptibility is NOT normal based on my experience with typical recreational scuba divers.

I think this was the post I had remembered reading when I indicated that it was my impression that she was significantly MORE susceptible to narcosis and the self imposed 100 ft depth limit was not simply a case of following a training/agency directive.

So I think this evidence validates the speculation that when she got forced down to 130 ft (or more) that narcosis could have been relevant.

Nothing indicative of "more susceptibility" IMO; just an honest appraisal of what breathing gas gave her better cognitive clarity and situational awareness.

It's whatever made her feel more comfortable during her dive --and that's all that matters.

http://www.scubaboard.com/forums/ad...-collecting-narcosis-stories.html#post6860084

 

[MaxBottomtime]

I think some of the confusion is from the things Lynne wrote about herself.
"SOMETHING is just not right in my brain at the 100 foot level. We can disagree about what it is, but in the future, for any dive that involves significant time at that level, I'm going to have something other than Nitrox in my tank."
http://www.scubaboard.com/forums/ba...11-narcosis-insidious-subtle.html#post5706536

 

[Adobo]

Having just done Ginnie Springs on 30/30 for the first time, I can enthusiastically and with complete conviction report that, for me, the answer is YES. Not only do I remember more than a vague, dark gestalt of the cave, but I came out for the very first time ever without a pounding, horrible headache and nausea. It was a totally different dive.

This post would seem to refute this idea. She indicates here that she was unable to do a good job at even REMEMBERING a 100 ft dive.

This degree of narcosis susceptibility is NOT normal based on my experience with typical recreational scuba divers.

I think this was the post I had remembered reading when I indicated that it was my impression that she was significantly MORE susceptible to narcosis and the self imposed 100 ft depth limit was not simply a case of following a training/agency directive.

.

Ginnie Springs is not remotely anything like most "recreational" dives. Even entering the cave system can be an ordeal for those who do not have the appropriate training/experience.

 

[beester]

To get back on topic... I think if He was as cheap as O² then more people would use it shallower, the additional benefits outweigh the risks (ascend).

I believe when people decide on Tx/HeO² vs air there are a lot of factors in play no?
- Logistics, availability and price of He... diving Chuuk lagoon will probably be with a leaner or no mix at all because of the costs involved.
- Training & Experience: Identifying risks is of course based on your training and experience.
- local diving circumstances: visibility, cold, dark, current
- And then the biggie, your personal risk vs reward balance...

Pulling the safety card during such discussions doesn't convince anybody, because the other party simply will not recognise the risk or will think you over-estimate the risk. I know divers who went to 100m(300ft) on air and have a picture of their divecomputer at that depth on their fridge door. I've dived with a guy (and it was my last dive with him, because I was so pissed off) on a tropical reef who without any planning or notice dropped like a brick to 56m(185ft) on nitrox 28... I went after him, because I thought he was incapacitated, he was not.. he was just stupid.

I personally try to balance the above and make a (hopefully) informed decision. For example I'll easily dive 25/25 or 30/30 on a very shallow 25-30m(80-100ft) north sea wreck dive if we are doing a ghostfishing wreck cleaning dive. Bad visibility, current, "working" underwater, work of breathing... all amount to a possibility of CO² retention and maybe a darknarc... so I like to avoid that and have a easy breathing mix. It helps of course that for these dives the ghostfishing organisation will pay half the gas bill. On the other hand I'll dive to my personal air limit of 40m(120ft) if the conditions are benign (warm tropical water without current). If it's warm tropical water with a lot of current I would err on the shallow side of this limit. Finally overhead will always be mix in my book.

If someone doesn't agree to these limits I'll politely agree to disagree and just won't dive with them. If they agree and then during the dive just exceed what was planned it's my last dive with them.

Of course within my local GUE community this never poses a problem, but with the cmas crowd it does from time to time.. I've long ago learned that it's very hard to impossible to convince someone why your personal narcosis (END) limits are what they are, so I just inform people and if they don't subscribe to it, I won't discuss... I just won't dive with them... and let them on their merry way. The sea is big enough for all of us.

I've only met Lynn once and had some email conversations with her on diving on the Tala, that's all. So I don't assume to know her but reading her many posts on this and other diving topics I sense that her risk vs reward balance was very much on the side of caution. I don't think that being cautious has anything to do with your diving skills, You are not a good or a bad diver because you are a risktaker or cautious. However when it comes to technical diving... I'll always pick the cautious buddy ;-)

I feel very sorry about what happened to Lynn, nobody knows what caught up to her, a cascade of small issues or 1 big one, would a light mix with a lower ppo² have helped? Nobody knows, that's just speculation, but I guess when she made the decision to dive the mix she dived on that last dive, it was an informed decision based on the information at hand.

 

[MXGratefulDiver]

Having just done Ginnie Springs on 30/30 for the first time, I can enthusiastically and with complete conviction report that, for me, the answer is YES. Not only do I remember more than a vague, dark gestalt of the cave, but I came out for the very first time ever without a pounding, horrible headache and nausea. It was a totally different dive.


I've dove with hundreds of divers. I don't remember any of them telling me they could not recall their dive to a depth of 100 ft. She is clearly implying that she was significantly impaired. She is implying also that her dive in Ginnie Springs was to 100 ft. Is it possible it was deeper?


Edit:

Well I just read a portion of that 2010 thread..

The (expensive) lesson I learned is that I will no longer dive deep Florida caves without helium in my breathing gas. I am too stupid to be safe at 100 feet without it. And the lesson for the rest of you is that you don't necessarily need to feel any different at all to be stupid at depth. You can manage your buoyancy and your equipment and your navigation, but still miss things that are important. Don't underestimate the effects of nitrogen!

Not sure how beneficial it is to argue over "relative susceptibility" but she describes herself as "stupid" at 100 ft.

Personally, I do not expect people I dive with to be stupid at 100 ft.

... for those of you who haven't done cave diving, particularly in a heavy flow cave like Ginnie ... comparing it to a typical open-water recreational dive is apples and orangutans ... completely different things. It's significant exertion ... particularly for us line-following cave tourists from the PNW (where there are no conditions like that to practice in).

Lynne was describing a specific situation in those quotes. I used to get pounding headaches just getting to the mainline ... and that's just at 70 feet. But then, my technique for staying out of the worst of the flow sucked ... particularly if I was laying a line going in. It's a matter of doing it often enough to know what you're doing. Lynne got better at it in time ... but even she just didn't go to Florida often enough to develop the skill particularly well ... that's one reason why most of us from here prefer our cave diving in MX, where you don't have to fight a cave that's trying to spit you out all the time ...

... Bob (Grateful Diver)

---------- Post added November 12th, 2015 at 05:57 AM ----------

DD, the relevant point Lynne was making at that time was this:

". . . The (expensive) lesson I learned is that I will no longer dive deep Florida caves without helium in my breathing gas. I am too stupid to be safe at 100 feet without it. And the lesson for the rest of you is that you don't necessarily need to feel any different at all to be stupid at depth. You can manage your buoyancy and your equipment and your navigation, but still miss things that are important. Don't underestimate the effects of nitrogen!" http://www.scubaboard.com/forums/ba...11-narcosis-insidious-subtle.html#post5625936

... Bob (Grateful Diver)