Deco penalties

[xiSkiGuy]

Haladine is not outdated. Most of the computers manufactured today are based on the Haladine tables, check your computer specs. The Navy tables haven't changed in the last twenty years.

Isn't ignorance bliss?

 

[dumpsterDiver]

So how much does oxygen speed up deco compared to air? Is there a somewhat universally accepted figure for the increased offgasing rate? I sometimes use oxygen to help on deco, but to be honest, I'm not sure how much of a benefit I'm getting.

Last weekend I did 15 minutes on air at an average depth of around 200 (max 210) and my Oceanic hockey puck computer kept adding deco on the deep stops and I ended up with over 50 minutes of required deco. I usually bring some oxygen for part of the deco, but I'm really curious if there is a rule of thumb for oxygen. Could it be 5 times faster, because the N2 gradient is 5 times as high?

 

[rjack321]

So how much does oxygen speed up deco compared to air? Is there a somewhat universally accepted figure for the increased offgasing rate? I sometimes use oxygen to help on deco, but to be honest, I'm not sure how much of a benefit I'm getting.

Last weekend I did 15 minutes on air at an average depth of around 200 (max 210) and my Oceanic hockey puck computer kept adding deco on the deep stops and I ended up with over 50 minutes of required deco. I usually bring some oxygen for part of the deco, but I'm really curious if there is a rule of thumb for oxygen. Could it be 5 times faster, because the N2 gradient is 5 times as high?

You don't sound remotely deco trained here. 210 on air? Don't know how to plan you O2 deco time? Shuddder

 

[lamont]

very few of us could constructively critique Bruce Weinke's mathematics regarding (or even understand the math published in his Deco Primer),

I've tried going through Weinke's _RGBM in depth_ book, and the math appeared to be incomplete. Its a mathematical sketch of what RGBM looks like, but I don't think there are sufficient details in there to implement it.

If someone has implemented it from the descriptions that Weinke has published, I'd love to talk to them about it...

 

[rjack321]

I've tried going through Weinke's _RGBM in depth_ book, and the math appeared to be incomplete. Its a mathematical sketch of what RGBM looks like, but I don't think there are sufficient details in there to implement it.

If someone has implemented it from the descriptions that Weinke has published, I'd love to talk to them about it...

Its proprietary, shhhhhh.

Personally, I am very nervous about deco algorithms which are "for sale" and not described by the author in a manner which allows people reproduce them independently.

 

[lamont]

Haladine is not outdated. Most of the computers manufactured today are based on the Haladine tables, check your computer specs. The Navy tables haven't changed in the last twenty years. Even with all the continued testing they have stood the test of time. So what are you afraid of? Use your tables, or computer, and dive the way you want. My point was that Geoerg Irvine and the DIR group did not invent scuba diving, or decompression diving for that matter.

George Irvine didn't invent the dual-phase decompression models that have largely replaced the US Navy tables either.

And I believe that US Navy is looking at updating their own tables with ones generated from bubble models because they've recognized that the existing tables are out of date.

 

[Rec Diver]

So how much does oxygen speed up deco compared to air? Is there a somewhat universally accepted figure for the increased offgasing rate? I sometimes use oxygen to help on deco, but to be honest, I'm not sure how much of a benefit I'm getting.

Last weekend I did 15 minutes on air at an average depth of around 200 (max 210) and my Oceanic hockey puck computer kept adding deco on the deep stops and I ended up with over 50 minutes of required deco. I usually bring some oxygen for part of the deco, but I'm really curious if there is a rule of thumb for oxygen. Could it be 5 times faster, because the N2 gradient is 5 times as high?

For me a 200' foot dive would require a 27 total minute obligation for decompressing on air. If I were to use 100% oxygen to finish my decompression instead of air I could reduce my total deco time to 16 minutes.

However, your computer shows an interesting situation were doing the, RGBM, deep stops actually adds time to your decompression obligation. It is not just your computer that does this, but so do the others I have witnessed, including my own. I find it interesting that the RGBM deep stop method regarded as being "new science" for deep diving will increase your deco time for a computer diving model. Maybe doing multiple, or extened time, deep stops should be questioned? Though I perform a deep stop it seems that extending the time greater than a minute also increases the decompression time. If you are not diving a computer that is compounding your deco obligation and you are using tables with out the ability to compund tissue compartments, could this lead to a hit.

 

[lamont]

Oh yeah...

Haladine is not outdated. Most of the computers manufactured today are based on the Haladine tables, check your computer specs.

Suunto Vypers and such have been using RGBM-modified haldanian models for a long time. Recently the D9 has come out which has deep stops added to it, so it can no longer be considered haldanian or equivalent to the navy tables at all. The v-planner, decoplanner and GAP software packages all have bubble models. Mares and Dacor now have computers with deep stops. The VR3 dive computer uses a bubble model.

The bubble models are computation much harder than haldanian models, which is why you see so many bubble-modified haldanian implementations like the Suuntos, but the trend is clearly towards to the bubble models -- and the higher end trimix tech diving computers are all embrancing the full bubble models.

Although I'm certain this is all just a plot by GI3 to brainwash the entire diving industry, and they're all just going along...

 

[rjack321]

Most of the cheaper air only computers are still haldane based though. Whether this is the majority of available models, I dunno.

 

[Rec Diver]

And I believe that US Navy is looking at updating their own tables with ones generated from bubble models because they've recognized that the existing tables are out of date.

I have downloaded the recent, 2004, Navy air tables. They are exactly the same as the 1984 air tables. What they have changed is the use of helium, and accelerated decompression. However, there is a different set of tables for that.