3 or 5 minute Safety Stop?

[tracydr]

You know I have just read back this whole thread and I believe I am now a bait for someone who is board on the July 4th holiday...

No, it came from another thread. Boulder John said there were references that 5 minutes have been shown to be safer than 3.

---------- Post added July 6th, 2013 at 03:11 PM ----------

Why are you conflating deep stops with extended safety stops? Also that quote wasn't a summary of the entire article, it was just one panelist's opinion. Cherry picking doesn't give a complete story.

Right. Somehow, the 5 minute safety top has gotten confused with the deep stop. Whole different topic of its own.

 

[uncfnp]

That seems odd, given the number of tech divers that I've heard of with osteonecrosis, which is most likely caused by untreated type 1 hits.
I'm also beginning to learn that those unlucky enough to have osteonecrosis may not have just DCS but different types of coagulation defects, such as anticardiolipin, ( lupus antibodies) or Leyden factor, basically similar to the same types of defects in the clotting system that puts a person at risk for deep venous thrombosis.
I've been doing research into this after finding out that I have multi-joint osteonecrosis myself, which seemed to have started after diving in Catalina this March. The orthopedic doctor doesn't believe its diving related and thinks it was caused by steroids given in 2007 but the fact is I began having pain right after we went diving. I had some tests done by another doctor doing research on dysbaric osteonecrosis and was positive for anticardiolipin antibodies as well as another genetic factor called PAI-1 (4g5g heterozygous). He's talking about trying 12 weeks of lovenox if I have a second high test for anticardiolipin antibodies next week.
Anyway, this is also part of why I've become more interested in decompression theory. The other reason is that I was planning to start taking some technical classes. When ( I don't plan to quit diving but it will have to be different and most likely sidemount ) I get back to diving, I will need to change my ascents and be as conservative as possible. I've dived for nearly 20 years and seemed to be fine until this winter. I have to figure out what was different this time. I do know my ascent rate was faster, mainly because I got vertigo while I was below 100 feet and had difficulty controlling my ascent. I had a hood that didn't fit and cold water was getting on my ears, making my ears frigidly cold.
Anyway, for now I'm just diving in my pool and doing a lot of swimming.

I'm sorry to hear of the problem you've been dealing with and can definitely understand your interest in deco theory. I have heard of osteonecrosis as an isolated complication of DCS but was not aware of the possible cumulative effects and the association with coagulation abnormalities (I vaguely recall something about platelets and blood vessel damage). Interesting. But it's never a good thing to be interesting in medicine. Hope all goes well.

 

[tracydr]

I'm sorry to hear of the problem you've been dealing with and can definitely understand your interest in deco theory. I have heard of osteonecrosis as an isolated complication of DCS but was not aware of the possible cumulative effects and the association with coagulation abnormalities (I vaguely recall something about platelets and blood vessel damage). Interesting. But it's never a good thing to be interesting in medicine. Hope all goes well.

Thanks. Was it you that had your own " interesting" DCS issue recently?

 

[uncfnp]

Yes. That's me.

 

[lowviz]

Doesn't 100% O2 also need an appropriate regulator? ...//...

Yes, your primary and secondary just have to be O2 cleaned. Just as important, open the cylinder valve VERRRRRY slowly EVERY time you open it. A cylinder of O2 is wonderful stuff on the surface.

...//... after finding out that I have multi-joint osteonecrosis myself, which seemed to have started after diving in Catalina this March. The orthopedic doctor doesn't believe its diving related and thinks it was caused by steroids given in 2007 but the fact is I began having pain right after we went diving. ...//...

There are a lot of things that are "Not inconsistent with...". Call DAN, find a specialist, make an appointment. Very best of luck to you.

 

[drrich2]

Doomnova:

It's true that multiple factors besides gender bear on SAC rate, and some are modifiable in theory with lifestyle changes (I say in theory, because for some of us, that simply will not happen) or skill acquisition/refinement (which hopefully does happen over time).

It is also true that some people come out of basic OW class without fine tuned skills yet have very nice SAC rates & can stay down a long time on an 80 cf tank. I suspect that if we surveyed large numbers of the low vs. high SAC fresh OW students, assuming roughly similar skill sets (they won't quite be equal), that smaller & leaner will tend to have lower SAC. And women tend to have lower total body mass than men.

Some outliers will be the exceptions that prove the rule. There will be some fairly big guys with good SACs.

There will be some people who, through good fitness levels & dedicated skill acquisition/refinement, will drive their SAC down and do well with an 80 cf tank.

But at the end of the day, I think that on average big, chunky guys who get no closer to the gym than driving by it occasionally are often either going to dive larger tanks when available, or else plan their profiles around parameters other than a strict 'rule of 3'rds' policy. Assuming excellent conditions, such as Bonaire shore diving or in a quarry.

If you're diving the open ocean with a real risk of popping up hundreds of yards from the boat and they can't see your head for the waves, or some such, then gas conservatism will be different.

Richard.

 

[maniago]

But at the end of the day, I think that on average big, chunky guys who get no closer to the gym than driving by it occasionally are often either going to dive larger tanks when available, or else plan their profiles around parameters other than a strict 'rule of 3'rds' policy.
Richard.

Just a funny quick comment on this specifically, and not to derail the thread, but I teach spinning (cycling aerobics) and have for 15yrs now and I'm a short light guy. But I'd love to have your air rate Richard as I suck down better than .8. Its not really that I have lousy aerobic capacity, but its the way I breath when teaching - huge lung fulls at high rates. Trying to re-learn to breath slow and deep is like running up hill backwards on my hands - opposite of my trained normal... Also of similar funny, when the AF had the cycling test as its PT standard, Id fail that too everytime. The fat smokers who walked by the gym on the way to the bar passed with flying colors - no joke. Funny how ironic life can be sometimes.

Now, back to your regularly scheduled program....

 

[chrpai]

Listening to people's SAC rates is just funny. Like I'm supposed to be impressed because someone can do an 80 minute dive and still have 1000 psi left.

To quote Popeye, I yam what I yam.

I know my physical weaknesses and I'm working on them. My SAC is what it is and I use that information for my dive planning.

Oh, and FWIW, it's the same .65 you got. So I guess we are in good company.

 

[scubadada]

Deep stops in recreational diving are, at best, a controversial issue. This has been discussed at some length recently in other threads. Peter Bennett was an outlier in his support of deep stops in recreational diving in the Alert Diver interview cited.

Though no expert, I don't know that silent bubbles are a proven, reliable biomarker predictive of DCS. I believe the relative merits of varying length of safey stop are unproven.

 

[tracydr]

Doomnova:

It's true that multiple factors besides gender bear on SAC rate, and some are modifiable in theory with lifestyle changes (I say in theory, because for some of us, that simply will not happen) or skill acquisition/refinement (which hopefully does happen over time).

It is also true that some people come out of basic OW class without fine tuned skills yet have very nice SAC rates & can stay down a long time on an 80 cf tank. I suspect that if we surveyed large numbers of the low vs. high SAC fresh OW students, assuming roughly similar skill sets (they won't quite be equal), that smaller & leaner will tend to have lower SAC. And women tend to have lower total body mass than men.

Some outliers will be the exceptions that prove the rule. There will be some fairly big guys with good SACs.

There will be some people who, through good fitness levels & dedicated skill acquisition/refinement, will drive their SAC down and do well with an 80 cf tank.

But at the end of the day, I think that on average big, chunky guys who get no closer to the gym than driving by it occasionally are often either going to dive larger tanks when available, or else plan their profiles around parameters other than a strict 'rule of 3'rds' policy. Assuming excellent conditions, such as Bonaire shore diving or in a quarry.

If you're diving the open ocean with a real risk of popping up hundreds of yards from the boat and they can't see your head for the waves, or some such, then gas conservatism will be different.

Richard.

I've had a very good SAC, even during my OW classes.