What defines a "Deco" dive?

[Jax]

Looks like Dwayne and Voodoo are still trying to slime Nicole and Steven. The boat changed their equipment to prevent the incident that happened so it seems something good came from this. Maybe you two can lose the hatred and go diving.

Agree that something is askew . . .

The deco discussion was getting very good, but when you start throwing made-up parameters in it . . .

I figure that those who were there would know if they crossed an NDL line . . . . I don't HAVE to try and make it fit my made-up version of a dive profile, because there are an infinite number of variations.

 

[VooDooGasMan]

Why would you do two dives on a set of doubles, when starting a gue class?

How much gas did you and steven have left after your first dive?

How is it easier to dive doubles then single tanks, in 4 to6' sea's, Plus loading and donnig them.

Lets see your download from the day of dive.

Nicole why do you now say you were doing both dives on doubles?


Scubasteve I spend a few hours a day in the water, everyday right now, and have for the past few months. the last few day's were a riot down under. There were down rigger balls going everywhere, I am checking out how the salmon strike lures and bait. How the seals strike the salmon once on line. Vis has improved a bit, better vis will be able to analyze a better feel on how to catch on a rod, and what makes them strike.

 

[ScubaFeenD]

Why would you do two dives on a set of doubles, when starting a gue class?

How much gas did you and steven have left after your first dive?

How is it easier to dive doubles then single tanks, in 4 to6' sea's, Plus loading and donnig them.

Lets see your download from the day of dive.

Nicole why do you now say you were doing both dives on doubles?

And exactly WHO made you grand inquisitor?

 

[ScubaSteve]

Your bias is clear voodoo. I don't care if you spend 24 hours a day in the water. Your ability to latch on to and obsess over some nit of information is astounding. You and Dwanye are trying your darndest to make Nicole and Steven look bad and for what? To get even for their perceived (perceived by you) wrong doing? What you guys are arguing has nothing to do with the original topic.

 

[Jaydubya]

How is it easier to dive doubles then single tanks, in 4 to6' sea's, Plus loading and donnig them.

personal preference but I like diving dubs vs 2 singles in big seas since no need to change tanks on rocking boat. dubs too gives more reserve gas in case i need it. no comparison for loading. i choose dubs every time. I can carry dubs on my back and my gear bag and other crap at the same time. with singles I have to make an extra trip to the boat. can even do 3 tank day on a set of 120s.

 

[UCFKnightDiver]

Agreed, something to be said for not having to switch over tanks in pitching seas!

 

[TSandM]

Did anybody notice that this thread is NOT the Marissa thread? This thread was deliberately split off, so that we could have a discussion of minimum deco and whether minimum deco dives are considered "deco" dives or not, and get that conversation away from the issues of the specific incident. Please, can we keep this one to the topic as designed?

ScubaFeenD, I'm not entirely sure you are right about MDLs -- although the whole matter is confounded by the fact that there have been, over time, a number of DIFFERENT sets of MDL limits that have been published or taught by various sources. I began with the "120 rule" limits that AG teaches. I have also seen the dir-diver.com tables, and I understand GUE now has a table that comes with its Rec 1 class. But if, in fact, the limits were engineered by running deco software and finding what required one minute stops, then at least THAT software thinks you have to do them. Diving right to the limit of the table and then not doing the stops would be like exceeding the programmed ascent rate in another table; because there is so much conservativism (and so much uncertainty) in the models, you would probably be fine. But saying you can go directly to the surface at 30 or 60 fpm on an MDL dive would be like saying you could go to the surface at 90 fpm on an RDP dive. I'm sure people (including me) have done it, but it isn't advisable.

The fact is, most of us don't max out table limits on square profile dives. I can only think of a dozen or so dives I've done that were truly like that. One of the reasons I got some tech training was because, if I was going to do a dive that DID max out, I wanted to come at it the other way, and treat it as a mild tech dive, rather than an aggressive rec one. I can remember Mike Ferrara saying that over and over again . . .

And this brings up another idea for me. GUE puts divers in "technical" gear setups and teaches a kind of "technical" mindset for diving from the get-go, which makes it easy, even for someone who has no initial intention of doing any "technical" diving, to slide into more advanced dives and techniques. This whole "minimum deco" approach is a good example of that. Instead of moving from no stop (and often a not very carefully controlled ascent rate) into a whole new concept, the GUE-trained diver simple does longer versions of the same kind of stops he's already used to. (And I have to say that longer stops are actually EASIER -- keeping that 30 second stop/30 second move schedule can be a real challenge!)

 

[VooDooGasMan]

No doubt about it jay, And a lot of divers do also. and there are even more reasons then What you have posted.

No one feen, I call it as I see it. When a diver post and comes up with hidden info later, or changes there motive in a dive, explain why you have done so or don't post.

Very thing that has been posted before, 40 min dive, and this is not a technical dive. Seen different responses, after this and the latest one is the gue format of doing stops on a not madatory deco dive.

Dr Bill even asked what is this way of theory to gue/dir deco.

So If you are so concerned of a safety practice, you need to make a business change there way's in what you think happen. Then why are you performing unsafe dive practices that are against deco and air management.

Jay I fill my tanks way beyond and get many dives out of all different size bottles, and this gives me lots of deco time, sort of like the deeper stops that is mention in this post.

Getting bent is a fear that brings all of this to perspective, having slow ascents, minimal nitrogen build up and diving mixed gases is what is the theory is to achieve safe dives from not getting bent. Then other things come in to play.


Divers that dive Al 80's for years have an advantage over other divers. they have become great at there sac, where the more CF on a diver from the get go is how they dive. We all have a pressure gauge, and follow it down to the given 500 psi.

Deco diving theory has now different amounts of gas supply, cause of multiple fill pressures to get the approved CF. This of course is not a difficult thing to figure out. Yet older seasoned divers have a much better dive profile in the gas supply to perform safe deco dives if needed, Where as ones that are at 100 CF or bigger have been conditioned to dive with more CF of gas.

A divemaster in warm water diving AL80 is along the same reigns.

Deco diving is a fun math theory, its even more fun for Recompression.

To do the deeper stops is only a theory of diving that has came a long the wheel.

When doing a multilevel dive, you are now being more accurate in your nitrogen loading, therefore ascending to shallower depths and leveling out has made dives longer, now if on a deep wreck there is an ascent line and there is some multilevel diving, but not the rest of the way up the ascent line. So now you have make your own and this is where we find doing a deeper stop after ascending is now a deco theory.

I was taught to slow and stop on the way up from wrecks when I started diving, yet under stood it in the multilevel diving.

The funniest thing I like to see, when a person ask me about getting bent, and only has a little knowledge, they comment the air bubbles, and I say I hate it when I am diving deep and a buddy, He has a problem and fly's to the surface, they ask why, I reply that once they surface all the bubbles blow there head clean off, and then it sinks and I catch it, now I have the sea life all over me, then when I hit the surface its like caring a bowling ball.

 

[ScubaFeenD]

ScubaFeenD, I'm not entirely sure you are right about MDLs -- although the whole matter is confounded by the fact that there have been, over time, a number of DIFFERENT sets of MDL limits that have been published or taught by various sources. I began with the "120 rule" limits that AG teaches. I have also seen the dir-diver.com tables, and I understand GUE now has a table that comes with its Rec 1 class. But if, in fact, the limits were engineered by running deco software and finding what required one minute stops, then at least THAT software thinks you have to do them. Diving right to the limit of the table and then not doing the stops would be like exceeding the programmed ascent rate in another table; because there is so much conservativism (and so much uncertainty) in the models, you would probably be fine. But saying you can go directly to the surface at 30 or 60 fpm on an MDL dive would be like saying you could go to the surface at 90 fpm on an RDP dive. I'm sure people (including me) have done it, but it isn't advisable.

If you use the rule of 120 or 130 (depending on gas used) and you run the plan through v-planner you will get profiles that mirror a direct ascent to the surface or the inclusion of a "safety" stop like in other agencies (especially if you include a short stop at 0.5 max depth as I was taught in NAUI EANx) Regardless, when i dive an MDL/NDL dive there is no point during the dive where I consider it completely unsafe to go to the surface in a total emergency and have done so in the past without ill effects. Perhaps you more prone to DCS in that case, but if the emergency is great enough (such as sever hypothermia) I would rather get on the boat and get on O2 and begin treatment than worry about violating a prescribed minute- 3 minute stop (which is was vplanner gives for pushing the MDL to the limit based on the rules of 120/130).

On a "deco" dive, where decompression stops are mandatory due to the gas or profile, it is a completely different story.

I was trying to highlight the differences between the two concepts for some of the more stubborn members of the discussion.

Nonetheless, GUE uses MDL stops to slow ascent rates to control bubble growth and to slow ascent rate, which is more in accordance with VPM type diving than it is with Buhlmann which would indicate getting up and establishing a higher gradient is the goal. Further, the training is meant, as you mention, to set you up to go into more intense training where holding stops is absolutely necessary, and practicing that, even on "recreational" dives is a great idea.

 

[scubadada]

I wonder what NDL plan was being followed... As originally planned 6+ mins of deco.
Decompression model: VPM - B

DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 2

Dec to 90ft (1) Nitrox 32 50ft/min descent.
Level 90ft 40:12 (42) Nitrox 32 1.19 ppO2, 73ft ead
Asc to 20ft (44) Nitrox 32 -30ft/min ascent.
Stop at 20ft 0:40 (45) Nitrox 32 0.51 ppO2, 13ft ead
Stop at 10ft 6:00 (51) Nitrox 32 0.42 ppO2, 4ft ead
Surface (51) Nitrox 32 -30ft/min ascent.

Off gassing starts at 51.6ft

As dived...

Decompression model: VPM - B

DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 2

Dec to 100ft (2) Nitrox 32 50ft/min descent.
Level 100ft 20:00 (22) Nitrox 32 1.29 ppO2, 81ft ead
Asc to 75ft (22) Nitrox 32 -30ft/min ascent.
Level 75ft 20:00 (42) Nitrox 32 1.05 ppO2, 60ft ead
Level 75ft 2:00 (44) Nitrox 32 1.05 ppO2, 60ft ead
Asc to 10ft (47) Nitrox 32 -30ft/min ascent.
Stop at 10ft 1:00 (48) Nitrox 32 0.42 ppO2, 4ft ead
Surface (48) Nitrox 32 -30ft/min ascent.

Only a minute of deco. Using +2 level of conservatism but even at +0, the first dive was still a deco dive. Ratio deco to find max NDL? Navy tables max NDL?

By the by - Found a link to the NOAA tables... http://www.ndc.noaa.gov/pdfs/nitrox32.pdf

Is this a trick question or is it making an incredibly simple concept into something more complicated?

Good diving, Craig