Whats Wrong with VPM-B

[rjack321]

Well, my tech instructor told me that, on shallow staged decompression dives, as long as you do the total time, it probably matters very little WHERE you do it, at least in terms of full-blown DCS symptoms. My Cavern instructor is a tech instructor, and he does ALL his technical diving on a basic Buhlmann profile, using only 100% O2 for accelerated decompression. He's been doing it for years and teaching it for years, and he doesn't have any dysbaric osteonecrosis I know of

I really doubt Hermann is diving a Buhlmann profile without any gradient factors (100% low/100% high). I also imagine he dives alot of air for which a Buhlmann model seems more accurate (by Buhlmann's own admission) than trimix.

 

[Kern]

Well, my tech instructor told me that, on shallow staged decompression dives, as long as you do the total time, it probably matters very little WHERE you do it, at least in terms of full-blown DCS symptoms. My Cavern instructor is a tech instructor, and he does ALL his technical diving on a basic Buhlmann profile, using only 100% O2 for accelerated decompression. He's been doing it for years and teaching it for years, and he doesn't have any dysbaric osteonecrosis I know of

I think it's generally accepted that a slower curve is preferable, but I'm not at all sure that there are hard data to support that, and there are some data that show that the extremely deep stops that some folks are adding to their profiles actually result in higher bubble scores.

Obviously the less you've moved away from NDL's the less difference it will make.

If someone approached me to be their buddy on an 80mt trimix dive however, & said I use vanilla Buhlmann, & only use O₂ as a deco gas, I would have to decline. Why, because he's only going to have 2/3ds of the deco time I'll have, & his curve is going to start at a very different depth & follow a different path, so hard to be a worthwhile buddy.

 

[TSandM]

Richard, I don't know if he uses gradient factors, but I do know that he uses one deco gas, and that's O2, regardless of the depth or duration of the dive.

 

[nadwidny]

Richard, I don't know if he uses gradient factors, but I do know that he uses one deco gas, and that's O2, regardless of the depth or duration of the dive.

You need a better instructor.

 

[Slamfire]

Well, my tech instructor told me that, on shallow staged decompression dives, as long as you do the total time, it probably matters very little WHERE you do it, at least in terms of full-blown DCS symptoms. My Cavern instructor is a tech instructor, and he does ALL his technical diving on a basic Buhlmann profile, using only 100% O2 for accelerated decompression. He's been doing it for years and teaching it for years, and he doesn't have any dysbaric osteonecrosis I know of

I think it's generally accepted that a slower curve is preferable, but I'm not at all sure that there are hard data to support that, and there are some data that show that the extremely deep stops that some folks are adding to their profiles actually result in higher bubble scores.

Given the lack of data, human trials and other hard numbers, I wouldn't label such practice as totally wrong. After all I understand this was what people used to do before Pyle got popular. However, bunching up all your deco in the last few feet before getting to the surface would make for a long, boring dive. Personally, I really like taking the time to enjoy the scenario at various depths. At least this is my opinion for the typical wall dives you have in Western Canada. I'm sure in other dive environments like certain caves circumstances may be different.

 

[TSandM]

Brian, I didn't take technical instruction from him, I just took Cavern and Intro -- and followed them with Cave 1

 

[AbyssalPlains]

... having the option to choose as a consumer is very nice.

Liquivision Marketing & Sales Manager

In this case, to me it feels more like a burden. I don't want to complete a PhD in decompression theory, I just want to dive safely, according to what the latest science says. Just as I don't feel like completing an MD before getting a treatment for an illness, I'd rather rely on an expert who has studied the data to tell me what I, as an "end-user" of all this theory, should go by.

Is there such a thing?

Yes, basic question, I know. I'm just getting into technical diving. So far I've completed only a handful of technical dives. It's hard to do in Southern Arizona. But I'm hoping to get to do it more frequently.

In my deco class, I learned that V-Planner was the software to go by. Is that no longer advisable?

 

[rjack321]

I'd rather rely on an expert who has studied the data to tell me what I, as an "end-user" of all this theory, should go by.

You'll find alot of purported experts but almost no data.

You need to continue to learn and come up with your own best practices as you go. Get used to being a guinea pig and take good notes.

 

[BB1]

Ross,

I guess I need to clarify the science part of my post.

Your position appears to be that VPM is the ONLY algorithm that works and that VPM is clearly SUPERIOR in some way.

That position has very little support in the scientific community.

My position is that BOTH algorithms produce plans that are usable in most cases. We plan to implement the algorithm to allow the diver to plan dives that don't violate either algorithm if they chose. It is also my position that the amount of exercise during bottom time and decomression and the temperature of the body during bottom time and decompression are both big factors in successful decompression.

I think I can say that my position is very much in line with the general beliefs of the scientific community.

Bruce

Funnily enough both those factors are monitored and used to adjust the deco obligation by the UEMIS as far as I know.

 

[rjack321]

Funnily enough both those factors are monitored and used to adjust the deco obligation by the UEMIS as far as I know.

Yup.
They apparently don't expect you to stick to a plan.

BTW the Uemis is ZHL-8 so pretty rudimentary underneath the temperature and workload compensation do-hickies.