What makes us think we can trust any of them

[Snowbear]

Seriously, does this really occur and what are the symptoms? I've never heard of it and dive almost exclusively with female buddies if I'm not solo.

Yes it does, but I'm not sure how common it is, since most women (for obvious reasons) would rather not talk about it on a dive boat full of guys.

I've linked a couple of previous threads on the topic:

http://www.scubaboard.com/showthread.php?t=72974
http://www.scubaboard.com/showthread.php?t=147 (this one's ancient!)

And please guys, this really is a serious topic. Any immature, tasteless jokes will be deleted.

 

[Snowbear]

I am curious re what the couple of things you told her were? Always looking for ways to take the stress of the old body when doing repetative dives

Well, to start with, I knew she was not ready to give up relying on her computer, so told her to do as she was used to as far as not exceeding the NDL. But at the end of the dive, instead of making a direct 30fpm ascent from 40' or 50' (or whatever depth she's leaving the reef) to 15' and doing her 3-5 minute "safety stop," I suggested she start her ascent a little earlier to have enough gas. I suggested she watch her computer and ascend at no more than 10fpm or one ascent indicator bar on the computer. Then when she gets to 30', stop there for one minute. Then spend a minute getting to 20' and spend another minute there. At this point, her computer should have started the 3 minute safety stop countdown, so I had her spend the rest of this countdown getting to 10', then spend a minute there. Rather than pop to the surface, I had her ascend so slowly that the ascent would not register on her computer, or at most show a single bar.

After the first time she tried this after a long 100' dive where we ended up leaving the reef at about 50', she was practically jumping up and down. She said she could not believe how much energy she had and that she has never felt so good after a dive. I knew she would feel better, but this difference was dramatic! And to think - she was actually doing absolutely nothing wrong according to any commonly recognized standards.... she was hydrated, fit, diving EAN32, ascent rate <30fpm, dives well within recreational depth and time limits as well as well within her computer's limits, consistantly safety stopping for 5 minutes, had good buoyancy control so wasn't doing "sawtooth" profiles :14:

As the week went on, we talked a lot about the reliability (or should that be unreliability ?) of essentially allowing a computer to run our dives. She was flabbergasted that without a computer, I was consistantly doing deeper and sometimes longer dives than they were. I told her to pay attention to my profile..... that towards the end of the dives, I would likely be a bit shallower than most of the group

 

[Cacia]

I am no expert on this but would like to say that it is my understanding 1 out of 5 people have some degree of POF. It would be prudent if you were having an echo (more and more common) to ask to have this ruled out as it may dictate your need to dive more conservatively. 20% is high enough that we should certainly realize this plays a factor as well as the "theoretical" nature of the models used. Correct me if I am wrong. Once bubbles aggregate and get pushed into the circulation, one could get bent literally anywhere blood flows, yes? Venous being much less serious than arterial, but that is why POF is an issue.

As far as mammary bends go, I would bring up silicone vs saline, but I know better. AND please do not delete me because there are medical implications, I am not trying to be cute.

 

[WarmWaterDiver]

I would be extremely interested in data on "undeserved hits" that occur to divers using procedures like Snowbear uses vs. divers using dive computers vs. divers using tables. Unfortunately, it is difficult to weed out statistically meaningful data often from DAN or BSAC publications unless one is very judicious in framing the use of the data.

Is there a way for those of you who are dive professionals to get these organizations mobilized on such a study? For we who earn our living otherwise but enjoy diving, the only thing we have to vote or mobilize with that has any real voice or impact are our $$$ (or similar equivalent outside the USA). However, such data might be helpful in guiding where our dive $$$ are spent.

 

[Snowbear]

I would be extremely interested in data on "undeserved hits" that occur to divers using procedures like Snowbear uses vs. divers using dive computers vs. divers using tables.

Just to be clear.... what I suggested to the gal on the boat is not how I dive.... I was just trying to give her a better (aka more conservative) way to end the dives she was already doing and wanted to keep on doing

 

[Darnold9999]

Thanks for sharing Snowbear, that was what I was looking for.

I have just started doing more diving and more diving on a single day on a slightly used body so am starting to pay more attention to such things.

For what its worth I do keep a mental model in my head (and always have). I think of my body as a giant bottle of soda - the deeper I go and the longer I stay the more bubbles get pushed in, so when I surface I am trying to open the top as slowly as possible with no bumps to create bubbles. Keeping a balance between getting to the surface with air still in my tank and letting the bubbles out through my lungs by breathing. The idea being that if I am gentle re surfacing and take my time the gas will escape with no bubbles left in me. No bouncing up and down no shocks by surfacing too quickly particularly the last 10 feet or so. Like taking the top of soda - remove the pressure too quickly and it foams over, nice and slow and leave it out for an hour or so and it goes flat - no bubbles.

Incredibly simplistic and wrong gas, I know, but so far I find if I keep this mental model I dive pretty conservatively. It seems to be so imbedded in my diving that I find myself a little stressed if I get too deep too long.

 

[pipedope]

Please remember that gas loading, NDLs and decompression are not an exact science.
There is a wide variation between individuals on any given day and a wide variation even in the same individual from day to day.

Trust a computer? Not me! I don't trust this one and I am not using it in anything nearly as risky as diving.
I have no problem using a computer. The computer is a tool and can give me useful information that helps me but I am in control of my dive, the computer is not.

With or without a computer it is still the diver who needs to understand what is going on and make good choices.

 

[gecko3s]

The main problem with computers is that people have come to rely on them too heavily. When you're at depth and your computer fails...Will you have worked out your dive on the tables, by hand, so that you know what you need to do in order to continue? Or do you just quit?

 

[Nemrod]

"No DCS incidents in 45 years of diving... so far."

I doubt you were using a computer 45 years ago or did you have one of the BendoMatics?

Mammary bends, never heard of it, what exactly did you tell her to set her straight in case I run across such a thing? I am not intending this question to be funny? N

 

[WarmWaterDiver]

Just to be clear.... what I suggested to the gal on the boat is not how I dive.... I was just trying to give her a better (aka more conservative) way to end the dives she was already doing and wanted to keep on doing

No problem I wasn't thinking of different interpretations possible when I posted. Hopefully this helps clarify from my end.

I found the Undercurrent article earlier in May 2005 on DCS interesting (and it was based on DAN data, titled "Who Gets Bent More?"), and I posted my thoughts on that data in another thread here a while back. I don't know of any published data on incidence of DCS, whether done "within limits" (i.e. wholly within the guidelines for this style) or not, by such procedures as you mention. If such data was organized, and it clearly indicated a significant reduction in "undeserved hits" in particular, and published for public review, it could be extremely helpful. If anyone can direct me to where such data might be already published, I'd appreciate it.

The trouble with anecdotal evidence is it is anecdotal. This doesn't matter what the subject under discussion is. One person's great experience can always mean someone else's bad experience due to our variation as individuals. And on this topic, even our own individual variations from day to day or on even smaller time frames than days - even possibly hour to hour.

String published a link to the 2005 BSAC report recently, and has subsequently posted a number of times on that thread where folks are trying to draw conclusions from the statistics.

As mentioned by others, each individual's predisposition to DCS makes for no guaranteed "one size fits all world", going back to the title of the thread. The only known guarantee to not get DCS is to not significantly change the ambient pressure one's body is exposed to, including activities such as scuba diving.

Pipedope summed it up well; I no more blindly turn over how I manage my dive to a computer than I do the operation of my pickup truck when I drive it, although it uses a computer for a number of functions. I'm still the most critical part - "the nut behind the wheel" - controlling speed, direction, deceleration, acceleration, how I fit into the traffic pattern etc. as well as how I compensate if something doesn't work like it should. But the information I am given by the computer in either application assists me in performing the task at hand.

The consequenses of blindly choosing not to steer one's one course would in time be an injury, in either application. However, education can really help how one manages the task, and allows one to make choices based on something other than what someone selling a product puts forth (whether vehicles, dive computers, or other items), or what someone else said, or what their instructor uses, etc.

It would be interesting also I suppose to get absolute statistics on divers who would fill out a form of some sort and check off that they do blindly turn over such control of their dive solely to a computer as mentioned by others, but it would be difficult I think to get a statistically significant number of honest answers.

I am quite serious - I have not mentioned anything on the gender sensitivie section of this thread because DCS and management of DCS avoidance is the real topic under discussion as far as I'm concerned. I don't want my dive buddy / wife to have an avoidable (significantly predictable) DCS experience any more that I would want to experience one myself.