deco comparison

[TSandM]

I always wonder about the people who get exercised about posting schedule details on the internet. All the programs we use to generate these profiles are available for purchase, and nobody checks cards before you buy them. Even the Ratio Deco class is available on line, in a skeleton version and in a webinar full version.

What we might post here is only what a determined person is going to get, anyway.

 

[Amphiprion]

Correction, RMV was .7 last I checked. If it was 7 then I would go to a hospital.
I threw out the gas mix as hypothetical. Typically I use ideco. I as trying to figure out if it would be worth while to get vplanner, some RGBM program or other non buhlman (sp?) software if deco was accelerated with one of these (first stop deeper and longer for example) or if gas required was less. Perhaps I shouldn't post when I am am tired and about to go to bed.

Also, I am not asking anyone to plan a dive for me. If someone uses a posted plan as their own plan we can all have a good laugh in the accidents and incidents forum at a later date.

I'd love to take a class on gas physiology with the available models (heck, we could throw in other gasses such as Ne, SF6, H2 and CH4). Unfortunately, I don't know who teaches this class.

 

[Amphiprion]

Also, no clue why I posted ANX instead of EAN. Maybe I was thinking EANx? Again, the risk of posting when I am about to go to bed.

 

[ScubaFeenD]

Correction, RMV was .7 last I checked. If it was 7 then I would go to a hospital.
I threw out the gas mix as hypothetical. Typically I use ideco. I as trying to figure out if it would be worth while to get vplanner, some RGBM program or other non buhlman (sp?) software if deco was accelerated with one of these (first stop deeper and longer for example) or if gas required was less. Perhaps I shouldn't post when I am am tired and about to go to bed.

Also, I am not asking anyone to plan a dive for me. If someone uses a posted plan as their own plan we can all have a good laugh in the accidents and incidents forum at a later date.

I'd love to take a class on gas physiology with the available models (heck, we could throw in other gasses such as Ne, SF6, H2 and CH4). Unfortunately, I don't know who teaches this class.

Try reading the book "deco for divers" by mark powell. It explains, pretty broadly, the physiology of decompression and the different models used for calculating decompression stops.

If you already use iDeco then I suggest Baltic deco planner, which has VPM-B like vplanner and buhlmann models like ideco so that you can compare two different dive plans with one button. Its only 16$.

Nobody on this board will bother helping you with a deco profile, especially if you are untrained for mandatory decompression dives (I know because i got bit*hed at when i even mentioned a deco schedule).

 

[Amphiprion]

Try reading the book "deco for divers" by mark powell. It explains, pretty broadly, the physiology of decompression and the different models used for calculating decompression stops.

If you already use iDeco then I suggest Baltic deco planner, which has VPM-B like vplanner and buhlmann models like ideco so that you can compare two different dive plans with one button. Its only 16$.

Nobody on this board will bother helping you with a deco profile, especially if you are untrained for mandatory decompression dives (I know because i got bit*hed at when i even mentioned a deco schedule).

Thanks for the "Deco for Divers" tip. There are so many different algorithms out there for decompression diving, however classes tend to focus on diving skills and number crunching using standard tables. Nobody has taught me a scientifically backed "why" on Buhlmann versus VPM-B versus RGBM, etc. Likewise, I'd love to learn about other inert gasses plugged into these models. Perhaps this is too academic for a standard intro to tech or normoxic class. I was asking for run times from various programs to get a better understanding.

Despite my goofy typo ridden first post, I am actually trained in mandatory decompression, some trimix and advanced nitrox. (Intro to tech with trimix). Started the IANTD normoxic course last week.

 

[ScubaFeenD]

Despite my goofy typo ridden first post, I am actually trained in mandatory decompression, some trimix and advanced nitrox. (Intro to tech with trimix). Started the IANTD normoxic course last week.

Its hard to prove that though. I was just letting you know, from my experience, that these questions are rarely are entertained here. The book will really help you though. Enjoy!

 

[TSandM]

I'm not sure anybody can give you a "scientifically backed why" on the different algorithms. They can describe to you the difference in the assumptions (pure dissolved gas versus bubble, for example) and how that impacts the schedule the program generates. But so much is not known about the actual dynamics of gases in the body, and there is not all that much work being done to compare the various approaches to staged decompression diving, with respect to symptoms or to bubble scores (which are not the same, and may not even track that well).

In addition to Deco for Divers, I'd really recommend the GUE DVD, "The Mysterious Malady". I found it enlightening to listen to what people who ARE doing research in the field have to say about what we know, and what we don't know.

 

[rjack321]

I threw out the gas mix as hypothetical. Typically I use ideco. I as trying to figure out if it would be worth while to get vplanner, some RGBM program or other non buhlman (sp?) software if deco was accelerated with one of these (first stop deeper and longer for example) or if gas required was less. Perhaps I shouldn't post when I am am tired and about to go to bed.

There's no magic way to get out of the water faster. There are lots of different algorithms all with slightly different type1 and type2 hit rates too. So a "faster" method generally has greater risk its just tough to measure and quantify. At one point people were talking about the Navy deco tables having a 1-2% hit rate which is probably fine in a military operations universe but most recreational divers would consider that unacceptably high. I don't recall the source for this estimate but it nevertheless provides some perspective on what you might gain by trying more accelerated options. I don't really know the ideco algorithm so I'm not much help comparing and contrasting that choice. I think GAP is stupid expensive. V-planner works pretty well. Decoplanner has a great interface but I'm curious about its VPM implementation as it doesn't track with Vplanner's.

 

[dannobee]

I don't really know the ideco algorithm so I'm not much help comparing and contrasting that choice.

It's Buhlmann ZHL-16C with user adjustable GF's. Or VPM-B if you are a beta tester.

 

[Garth]

Let me preface this with: I'm not trimix certified either so this is from a gas planning standpoint only.

I ran the numbers you gave into ideco (.7rmv working and .5rmv deco)
I found that you are pushing your limits with only one bottle unless you are carrying an aluminum 80. If you are carrying an al40 I would consider adding another gas as previous suggested 50% plus 100%, or you could adjust your bottom time. A difference between the two would be about 68 minutes run time with 50% as deco and 59 minutes with 50 and 100.
For me I like to have 1.5 times the amount of gas in my deco cylinder. Adding another cylinder helps your odds if you lose your gas that you will have a backup for your deco.

put it this way... per ideco... if you lose your 50% mix you will need to deco 106min at your last stop on you backgas of 18/40 bringing your gas consumption up to 278 cuft of gas. Even if you get a good fill with LP108's or more you are going to be depending on your buddy. I assume you have a buddy right? If you don't then I would definitely consider another cylinder. Also an RMV of
.7 is okay but it might help to consider an RMV of 1 to help with conservatism.

Maybe I'm just way to conservative but running out of gas due to an obligation is not going to happen to me because i didn't plan conservatively. If it happens it will be due to a catastrophic event in which i hope never happens.

I've been grilled on the deco stop for pushing my training limits beyond my 150ft on air but i suppose I deserved it. Gas planning is important to me.