Deco penalties

[Rec Diver]

So you want to question the validilty of deep stops (newer bubble models) because your computer (older Haldane model) still thinks you are on gassing? That is exactly why some people argue that Haldane models are outdated and why most people doing serious deco are using their computer in gauge mode (and following Vplanner tables or similar) or using a computer like the VR3.

That is exactly why I stopped using a computer and went to a bottom timer and dive planning tables and software.

 

[MonkSeal]

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.

Although I read somewhere that it was complete, I also found that some math was missing.

 

[Rec Diver]

Last 200ft dive I did was a month and a half ago on the Minnedosa (a very, very nice wreck, by the way) in Lake Huron. It was for 25 min bottom time on 18/45 as backgas. Cut table with Deco-planner and used a bottom timer, with a second bottom timer and IANTD's 19/40 Table w/Accelerated Deco as back-up. Deco was 50 mins using 35/25 and 100% O2 for a total run time of 70 min.

You mean to tell me I spent an extra 45 minutes hanging on the up-line I didn't have to? I got to get me one of those computers that will talk me into getting to 20 feet as fast as I can and get me out of the water much quicker - Not!

I am a little confused over your math. You say you had a total run time of 70 minutes. Yet your bottom time and deco time exceeds that number. Putting that aside, what dive planning software do you use and how conservative do you set it for?you may bemore conservative than needed. However, this is total your call. I have read on this scuba board of a diver who claims to perform 15 minute safety stops at the end of his none decomprssion dive. He claims that he has never been bent. But, I haven't either even though I only do 3 minutes on such dives. Your conservatism is what you want to make of it. If you want to hang on the line longer then do so.

 

[rjack321]

Rec diver are you doing 200ft dives for 15mins on air with 16mins of deco on O2?

I also thought I heard you give this as a hypothetical profile. If no, your earlier post is confusing. If yes, how did you arrive at this schedule?

 

[lamont]

As you have mentioned the basis for these new computer models is still Haladine.

The D9 and VR3 or v-plannner/GAP/decoplanner don't produce anything like the schedules that a haldanian algorithm like the one used to generate the USN dive tables does. They are not haldanian algorithms and do not produce haldanian schedules.

 

[Azza]

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.

Haldane is so outdated it's not even funny. If you want to follow victorian era physics then go for it. I hope you live.

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.

The computer is running on a haldanian/ buhlman model. This is why it penalises you. This is why a lot of deco divers don't use computers. The algorithm is out of date.
We KNOW that bubbles form during a dive. Haldanian algorithms do NOT take bubbles into account. Everyone knows this...right down to a basic recreational divemaster.
Have you really had any formal deco training?

 

[Charlie99]

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.

Although I read somewhere that it was complete, I also found that some math was missing.

I haven't looked at his RGBM in Depth book, but a common problem in his Technical Diving in Depth book was undefined symbols, or at least ambiguous equations where one had to do a lot of puzzling and looking elsewhere in the book to find the definition of what was being used in his equations. Sometimes you had a couple different choices and it took a bit of grinding away to figure out which one he meant.

He needs a good editor.

 

[Rick Murchison]

He needs a good editor.

Understatement of the year. There are half paragraphs missing, incomplete sentences, ill defined variables... to say nothing of the incomprehensible disjoint writing style. I have no doubt he's a brilliant mathematician and decompression theorist, but his books need not only a heavy dose of proof-reading and editing, they need translation!
Just my (oh so humble) opinion
Rick

 

[Azza]

Oh good....I thought it was just me

 

[Thalassamania]

Dude.....you have things way mixed up. The presence of helium in a trimix is the reason why it is less narcotic. This is why END calculations only use the Helium concentration and do not include the O2 concentration. …

END calculations use the Nitrogen and the Helium concentration (at maybe narcosis factor=0.23?) and do not include the O2 concentration since it is not narcotic (Regardless of what you think that you felt, there is no data to support this. The only reference is Cathy Cush repeating something that she thought she remembered that Bill Hamilton might have said, phew!). In the case of any 21/XX mix there’s not need to figure oxygen, regardless of belief, since the mix is normoxic.