How many decompression dives do you have?

[aainslie]

i feel like my profiles are like dare devil profiles to what I am hearing. I use Vplanner on nominal, and usually throw a min or two in at half my max depth and a 5min saftey stop added to my last stop.

You're also half my age

[Bob Cree]

On the second

lol - touche', tongue and cheek...turned into a pretty good thread though. Truly, horribly boring, especially when it gets up there in time. You really know its bad when the fish get bored with you.

But I still do the deco - the true reason for a pee valve.

Ah, computer...by nature less conservative for the same algorithm due to following the profile. Have to admit in some cases to cutting special profile tables, like at Madison, 60 -120 - 60 feet, and use a deco mix on the outgoing shallow section. Not many places I would do this though. I dream on deco to do what my Nitek HE tells me to do. Damn decoplanner.

[atedeschi]

well since we are talking about deco, maybe we should see what type of conservation people are using and age of the diver.

I use Vplanner, nominal setting, and 5 mins to my 15min stop on O2, usually follow Dive Rite Duo when not using trimix, but average depth and v-planner are pretty close.

[Kelly Jessop]

In retrospect I realize my numbers would be skewed in that there was a cave diving era where nitrox wasn't readily available,or we'd use poor man's nitrox (topping air on top of a nitrox mix),so going into deco was quite prevalent,where the same dive today doesn't evoke decompression. I shiver at the thought of long air dives at Devils system,with long decompression times in a wet suit. Then again conversely,when nitorx was available we were diving 36% (and sometimes 38%-yikes),and we wouldn't hit deco,while a 32% diver would.

[netmage]

well since we are talking about deco, maybe we should see what type of conservation people are using and age of the diver.

35, VR3 SAFE 20 using VPM..., but thats mostly due to closed PFO & previous history... Probably equates to beyond a +5.

[apitkin]

I could equally claim that people who HAVEN'T been bent will tend to answer.

Do you have evidence for your claim? Because I sure don't for mine. Perhaps we should split the difference...

Anyway I just want to make the simple observation that assuming no biases in which of CDF's readers ansered iether or both polls (and it's a pretty high percentage of active readers anyway), CDF readers have a surprisingly high rate of getting the bends. About 40% have had some sort of incident, about 15% have taken rides (i.e. 25% (including myself) have had minor hits that they've treated themselves). Yet the average number of deco dives is way nearer 200 than 1000, leading to a hit rate of at LEAST 1 in about 500 dives - and I'm not even including victims of multiple hits (I've had two). I have NO causal variables, and I don't have the joint distribution - and franklly I'm not in a huge rush to collect those data. There MIGHT be bias in who chose to answer, but again considering the high percentage of respondents (especially to the first poll, which is probably the one most likely to induce bias), I doubt it.

But y'all take care out there - we're getting bent at a pretty high rate.

I have no more evidence than you, but what I am referring to is called recall bias in statistics textbooks and is one of the problems with this kind of retrospective analysis.

Having said that, I agree completely that cave diving is high risk for DCS and that we should all be conservative in deco planning.

Andy

[Bob Cree]

well since we are talking about deco, maybe we should see what type of conservation people are using and age of the diver.

As mentioned, I dive tables cut typically as square profiles from decoplanner 20/80 GF's. A while back, I used a Nitek Duo on its highest level of conservatism (SF2) as backup, and it matched up reasonably well with my tables as far as clearing on my last stop. Since the Duo does not give deeper stops (which I did anyway off my tables), it initially showed less deco obligation than the tables, but eventually caught up on the 20 foot stop. So I consider myself fairly conservative, but I am now 50 and have not been bent...knock, knock, knock...

One major cave/bends issue that I don't think has been mentioned is profile related. Sometimes back in the cave, the profile goes shallow suddenly and above the typical deep stop ceiling, then deep again. I have heard of people getting badly bent in these situations. One buddy of mine, years later, still suffers the consequences of this and they did get treatment.

[Randy Thornton]

Best thing I ever did to improve my deco was to install a pee-valve in my dry suit! Now, I am not in such a big hurry to get out of the water!