Gradient factors - deep stops thread in DIR forum

[scubadada]

would you choose 34 mins ?

the probabilities for 48 mins seem a bit high

I've dived DSAT for 17 years, nearly 1900 dives. I'm both successful and pretty set in my ways. I dive a Teric backup at 75/95 it matches pretty closely, a bit more liberal on some repetitive dives. You dive what you know. About 5% of my dives are light deco, all less than 15 min, generally less that 10 minutes, DSAT and Buhlmann match pretty closely.

 

[dmaziuk]

would you choose 34 mins ?

the probabilities for 48 mins seem a bit high

His bottom time at pDCS 0.43/80 fsw/EAN 32 is 68:51. Or conversely for 48 minutes BT it's .12 pDCS. The trick is he's factoring in a 3-minute deco stop at 3 m, I bet the others don't.

 

[Ayisha]

@Dr Simon Mitchell, you've posted in the past that you personally use 50/75. Do you still use these GF's, if you don't mind me/us asking?

Dr Doolette wrote in the recent past that he uses 70/85. Any comments? Thank you in advance if you're able to shed some more light on current thought.

 

[KenGordon]

I've dived DSAT for 17 years, nearly 1900 dives. I'm both successful and pretty set in my ways. I dive a Teric backup at 75/95 it matches pretty closely, a bit more liberal on some repetitive dives. You dive what you know. About 5% of my dives are light deco, all less than 15 min, generally less that 10 minutes, DSAT and Buhlmann match pretty closely.

Of those 1900 dives, how many were surfacing GFs > 70?

For your deco dives, did you do a safety stop after the mandatory stops?
For your non deco dives did you do a safety stop?

In other words, while the computer you had monitoring depth happened to be have limits at approx GF95, what did you actually experience as regards to tissue load?

What were the circumstances of these dives? Water temperature? Repetitive? Long or short surface intervals?

Would you dive those settings in the Fjords of Norway? Or at Bikini?

What you are doing here is giving the impression that diving to a GF of 95 is a fine idea because you have done it 1900 times and nothing bad has happened.

 

[KenGordon]

This thread has moved to concentrating on GF numbers. I think that a focus on the algorithm and these very narrow parameters is missing the point.

Everyone taking advice from SB should have a watch of

 

[rjack321]

This is all too common a story.
How does one avoid this delay and get into a chamber sooner?

1) IWR is (always) faster than any chamber.
2) Chambers aren't staffed 24/7, just getting a hyperbaric consult can take hours, then getting on-call staff mobilized etc. You'll probably get treated faster in a place like Cozumel where they see tons of (bent) divers. In PA where Trace is? It's going to be slow.

 

[jaseUK666]

1) IWR is (always) faster than any chamber.
2) Chambers aren't staffed 24/7, just getting a hyperbaric consult can take hours, then getting on-call staff mobilized etc. You'll probably get treated faster in a place like Cozumel where they see tons of (bent) divers. In PA where Trace is? It's going to be slow.

It would be faster in the UK too even with the recent cuts in search and rescue helicopters. I've seen 4 divers on 3 separate occasions helicoptered to the nearest chamber for rapid treatment.

 

[scubadada]

Of those 1900 dives, how many were surfacing GFs > 70?

For your deco dives, did you do a safety stop after the mandatory stops?
For your non deco dives did you do a safety stop?

In other words, while the computer you had monitoring depth happened to be have limits at approx GF95, what did you actually experience as regards to tissue load?

What were the circumstances of these dives? Water temperature? Repetitive? Long or short surface intervals?

Would you dive those settings in the Fjords of Norway? Or at Bikini?

What you are doing here is giving the impression that diving to a GF of 95 is a fine idea because you have done it 1900 times and nothing bad has happened.

Hi @KenGordon

I dived an Oceanic Pro Plus 2 from 2002-2010 and have been diving a VT 3 from 2010 to present. My first backup was a Cochran EMC-14, then an Oceanic Geo 2. I switched to a Dive Rite Nitek Q in 2016, to learn about Buhlmann ZH-L16C with GF. I have only had my Teric since last May, and only have about 100 dives on it. I have not had a chance to use SurfGF much yet.

My dives are very different than yours, I have never pretended otherwise. The vast majority of my dives are no stop. From my brief experience, I would say the usual SurfGF for these dives is in the 70s. Yes, I always do a safety stop, often 3 minutes, sometimes longer. The SAUL probabilities of DCS include a routine 3 min safety stop in the calculation. For the majority of these dives, I never closely approach the NDL of DSAT or the NDL of a GF high of 95.

For my light deco dives I satisfy my deco obligation and then do additional time at the last stop, often 3-5 minutes. I have only done a few of these dives with my Teric. I would guess that the SurfGF is usually in the 80s. So, even for these dives, I generally do not approach a SurfGF of 95

My diving varies quite a bit. I will often do just 2 dives a day, with a relatively short surface interval 30-60 min, when diving at home in Florida, though 4 dives per day in not uncommon. On liveaboards and when traveling, 3-5 dives per day is common. I dive wet. Most of my diving is in temperatures between the low 60s and mid 80s (17-29). I have less than 50 dives in colder water from 47-mid 50s (8-13). I've not been to Norway or Bikini, but have been fortunate to dive Red Sea, Cocos, Galapagos, Revillagigedos. I have dived the same algorithm, DSAT, on all my dives, for the last 3 years, along with a computer running Buhlmann.

My style of diving works out very well for me, within the spectrum of dives I describe. I make an informed decision, everyone else should do the same. As I've aged, I have become more conservative regarding the longer safety stops and the padded shallow time on light deco dives. I'm now learning how I want to incorporate the SurfGF available to me on my Teric. Believe me, I'd like to continue diving for as long as I'm able.

Very best and good diving,

Craig

 

[The Chairman]

No decompression algorithm has been tested in this context,

I agree and disagree. It's been tested all too often in real life and too many peeps have been injured or killed in the process.

I won't do more than two deep dive days in a row.

FWIW, I haven't done a 3 minute safety stop in years. 5 minutes is my minimum, even if none is required by my PDC. In the same vein, I add at least 2 minutes to any deco obligation i might incur. No, I don't do a lot of deco and I don't want to. We don't understand it fully and there's nothing down there worth dying for. It's all about limits and I'm not looking to find the raged edge in that respect.

 

[The Chairman]

@Dr Simon Mitchell, @RayfromTX has a great question... Are we injuring ourselves with these sequential deco dives? If so, are there symptoms we can look for? I'm having a hard time recovering from a broken leg. Yes, I'm an old fart who shouldn't break a leg in the first place, but I'm wondering if my bones have lost their ability to heal normally? I don't want to give up diving and teaching, but I certainly don't want to give up living or my quality of life.