100days-a-year
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The color of my apples is none of your business BTW,but I assure you their rate of fall is consistent with their age.
Suunto Tech RGBM dive profiles...
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You brought up that video... but take a closer look please.
You may not be aware, but that video is not accurate, or even correct. The Nedu did not test VPM or RGBM. The nedu's BVM test model has no relation to tech diving or VPM / RGBM what so ever. The BVM is a very shallow design, that bears no resemblance, visually or scientifically.
The connection is the one you got tricked with... word games, based on the word "bubble". That's not evidence, and its not science.
The Nedu actually tested elongated shallow stops (over double the required amount), vs the effects of getting cold. There are no deep(er) stops anywhere in that test. Some people make a great deal of implied association from that test to tech diving being made, but none of it actually exists.
Heat maps are not science, they show no actual dimensions, and are an over exaggerated comparison of harmless differences.
The simplified model used in that video, is not real and it is impossible to even create. It has no oxygen, and that missing most important aspect, changes how the off gas aspect / slow tissue on gas actually works. If the video actually used real math and real model gas formula, then the argument and conclusion diminishes to frivolous.
For a decade, the standard of dive planning was VPM-B / RGBM or a GF plan that emulated those. During that same period, tech training and diving grew significantly, using that planning as a basis. Recreational diving even adopted some of the bubble model attributes.
Also during that same period, the number of DCS treatments (both tech and rec) reduced to the lowest on record.
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Think about it.... a youtube video that attacks a very successful model and planning tool, by using inflammatory and invalid connections to science, supported with artificial model concepts, and verified by nothing more that the unsubstantiated opinion of one person.
Cheers.
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KevinNM
Contributor
A software developer without any formal training in physiology or decompression vs a collection of the worlds leading experts in decompression and diving physiology. You get to bet your life as to who is more likely to be least wrong, choose wisely.
Please provide any credible evidence to back this up.
The study did not have to specifically test VPM or RGBM, you can relate the same general principles across the models and draw conclusions from the comparisons (read: deep stops are not better than shallower decompression profiles). Dr. Dollette and Dr. Mitchell have both repeatedly shown how this data can be related to VPM and/or RGBM.
I have not run a profile to compare, but if in fact the BVM model gave shallower profiles than VPM/RGBM, then it suggest that it is even safer than VPM or RGBM. The general principle tested here was "Do deep stops provide more efficient/better decompression profiles?" The answer, based on the physical evidence, is no.
The model is a bubble model, there is no trick. The basic principles apply.
No, that is not what they tested. In simplistic terms, they tested one profile generated with a bubble model that had deeper stops, versus another profile generated with a gas content model that had shallower stops. The profile with shallow stops was statistically proven to result in less DCS. It is worth noting that the military was considering changing to a bubble model for their dives, and the results led to the conclusion that they should not.
They controlled for many factors that could possibly influence the outcome. There was no difference in temperature between sample groups, which means they were NOT testing "the effects of getting cold". The total dive time was the same for both profiles. They quite literally controlled for every factor they possibly could, with the only difference being the profiles had varying decompression stops/depths.
They are nice visual representations showing you the saturation of the varying tissue compartments between the profiles. They are science, just an easy to grasp (for some) visual representation of the data. If you have any data to back up your assertion, please provide it.
Please provide any credible evidence to back this up.
Just because people did things a certain way for decade, doesn't mean future scientific progress can't improve upon it. Also, the advances in technical diving are many, and are not solely the result of using "that planning as a basis."
As far as recreational diving is concerned, the safety margin on recreational diving calculation is so wide, the buffer negates being able to use it as evidence of superiority for VPM or RGBM over another method. You need studies like NEDU to be able to that, studies which push the limits so you can test the theory.
I have seen you state this before on the NEDU study debate. Please provide any evidence to back this statement up, or please do not claim it.
The connections to the science are real, and supported by the evidence. It isn't just verified by the 'unsubstantiated opinion of one person' it is the opinion of literally every researcher who is active in this field, dive medicine specialists, and anyone within the academic peer-reviewed circles. Please provide any peer-reviewed data or papers that suggests otherwise.
Again, please provide this evidence so we may review it. Or better yet, please publish your data for peer-review if you would like for it to be considered.
No, currently the choice is between real peer-reviewed science, versus the opinion of someone who hasn't produced any evidence to back it up.
By the way, that wasn't a 'made for youtube' video, but a presentation recorded and posted to youtube by DAN.
Cheers,
Landon
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EFX
Contributor
Agreed, if the physical evidence is based on deep stop profiles that are ridiculously exaggerated to support a conclusion already favored by the Navy (more on that below).
Here are the numbers from the NEDU study. Depth = 170 ft, BT = 30 min. BT = bottom time, DT = decompression time:
NEDU shallow stops (depth/time): 40/9, 30/20, 20/52, 10/93. DT = 174
NEDU deep stops (depth/time): 70/12, 60/17, 50/15, 40/18, 30/23, 20/17, 10/72. DT = 174.
Running the dive plan on my Perdix with VPM-B +2 gave this profile for the same depth and BT:
Deco stops (depth/time): 100/1, 90/2, 80/3, 70/4, 60/5, 50/5, 40/7, 30/14, 20/20, 10/34. DT = 95.
The NEDU deep stop profile doesn't come close to the VPM-B profile. The deepest stops for VPM-B are very short compared to the Navy's deep stop schedule (1,2,3,4 min vs. 12,17,15,18 min.). Also note that VPB-B gives much less DT. This is in keeping with the idea of limiting slow tissue on-gassing and the resultant super-saturation of those tissues which led to the DCS hits as reported in the Navy study, while limiting bubble growth beyond the critical size.
The conclusions drawn by Mitchell et al, are not based on actual scientific evidence (because no VPM-like profiles were tested) but were based on assumptions carried over to general deep stop dives. If you're going to test deep stop profiles based on bubble models than use a profile realistic to those used by actual PDC's that generate deep stop profiles. Duh!
It was amazing how much support (heat maps to think of one) the NEDU study received from both its extinguished authors and the SB participants, and not one word on how bubble mechanics promoted (or failed to restrict) DCS. The majority of the responses in SB were directed at support for lowering the amount of bubbles (offgassing) at the shallow stops following deep stops in excess of those generated without deep stops. The overriding conclusion was that the decompression strategy producing the least bubbles on surfacing was the correct one. However, this conclusion neglects the major science behind deep stops in that a lower gradient at the shallow stops may generate DCS due to larger size bubbles in the tissues. Deep stops as the theory goes provide smaller radius bubbles, an hence higher internal pressures, to reduce the gas flow into those bubbles. As bubbles grow in size their internal pressures drop causing lower gradient inert gas to enter those bubbles and enlarge them even more. There was no scientific procedure in the NEDU study to test the basis and validity of bubble mechanics.
I understand the motive for conducting the study as it was done. The Navy wants its divers to spend more time doing deco in shallower rather than deeper waters. If the divers get in trouble it's much easier to provide support in shallower than deeper seas.
With that being said there is an emotional appeal to using a non-bubble decompression model (Buhlman with GF's). The model is easily understood and easily adaptable through the use of GF's, and get this, to mimic somewhat what bubble deep stops do. In addition the algorithm is readily available on the net. Bubble models are not as easily understood and documentation not as readily available.
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EFX
Contributor
This is an argument from incredulity or its variant credulity. Your statement above is misleading as it doesn't distinguish scientific knowledge from conclusions drawn from that knowledge or its application which is not science. Here is an exaggeration of the same argument: Automotive engineers know more than you and me about cars. So I guess they must be better drivers.
Hi, As I said to you in the PM - not wasting my time on this again. You will need to do your own home work, or look up the hundreds of pages of data posted so far. If you don't understand it, then ask me to explain in private.
No. that is false. Neither have provided valid evidence connecting the nedu test to RGBM/VPM. There is lots of official sounding opinions, and The 5 different attempts at explanations made so far have all been shown to be inadequate and shown to be scientifically false.
There is no science connection from nedu to VPM/RGBM.... all there is are word games and deceptions, based on the word "deep" and the word "bubble", but no real science connection exists.
Trickery by Word association games are not science.
Then you should do some home work.... there is nothing like a BVM(3). it is a hand crafted very shallow profile.
That is the same logic that says ....all red cars are a Ferrari.
Your assumption is not true and the fact you are using a connection based on "word" association only, clearly shows how little science there is.
When we examine the Supersaturation graphs (using the same method / formula the nedu validates itself with), we find there is no connection or similarity to tech diving. End of story.. Math and science simply show there is no connection. Even worse is that filling in the missing supersaturation details in the nedu test, shows the nedu's own explanation of its findings, is not what really happened.
The test has NO relation to tech or deep or anything we do. They tested for a concept that does not exist in the tech world...
The real result of the nedu test..... is that models that follow the established gas tracking formula (like ZHL and VPM-B and every dive computer), these are OK. The profiles that can have trouble is the hand made things that ignore the basic gas rules... like some DIR style add-hoc mods.
Really? So the presentation was dumbed down for a group of peers, physics and science researchers and included a false model concept with no math, (an insult to the audience). And then it was edited for use on youtube??? Sounds more like it was made for the purpose of a public show.... to convince the unsuspecting with a flashy presentation, using scare tactics.
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KevinNM
Contributor
No, you are saying that the guy who wrote an iPhone app for configuring race cars should be trusted more than a group of world renowned experts on configuring race cars when you go to set up your race car. They don't have to know how to drive the car at all in order to tell you, based on their research and vast personal experience, what is most likely to produce a winning car.
I think the message is being lost in the attempts to draw parallels.
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The nedu test verifies its conclusions using the basic research standard of a series of mono-exponential gas kinetics formula (explained in its first paragraph). These are not complicated formula, and its high school level math at best. Now if we take that same formula and compare the VPM-B, vs the nedu test profiles, we can clearly see that no connection exists. It's that simple. The formula used to validate the nedu test, also vindicates VPM-B.
That is where the argument sits - the reality of science that shows VPM-B/RGBM is not connected to the test, vs the opinion of some who imply it is.
I have shown those graphs many times in the past and it remains scientifically uncontested. Divers can do the same inspection with the same formula, as these research standard graphing tools are inbuilt to MultiDeco (supersaturation graphing).
Cheers.
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