Deco with too less air, options from the book

[Kevrumbo]

Yes Bob, I've done both on separate dives to 45meters --on Air and 21/35 -- same RD profile.
(And of course, I felt much better post-dive hours later after the trimix dive than the deep air)

Mind you, Truk Lagoon is the only place I would do deep air because of its relatively benign conditions (warm 28deg C water, no current at depth and good visibility). . . But still, an obvious caveat that I learned the hard way three months ago: such conditions can also lull you into a false sense of security and over-confidence.

 

[Blackwood]

This question is for the peanut gallery, not just Kevin.

It is . . .what it is. And Ratio Deco was definitely used and practiced despite what you contend Blackwood. . .

If I run a profile in DecoPlanner, say 160 for 45 on 21/35, and I write that on a slate, and then I go dive 160 for 45 on air using the information on the slate, am I diving DecoPlanner?

 

[Bismark]

This question is for the peanut gallery, not just Kevin.



If I run a profile in DecoPlanner, say 160 for 45 on 21/35, and I write that on a slate, and then I go dive 160 for 45 on air using the information on the slate, am I diving DecoPlanner?

That is really too funny........

If I substitute gasoline for water, but follow the rest of the instructions in the firefighting manual...............

 

[Kevrumbo]

This question is for the peanut gallery, not just Kevin.



If I run a profile in DecoPlanner, say 160 for 45 on 21/35, and I write that on a slate, and then I go dive 160 for 45 on air using the information on the slate, am I diving DecoPlanner?

Try it Marc --a straight verbatim Decoplanner profile as crunched out by a computer for your hypothetical construct above . . .tell us if it works. Then try it again, tweaking/optimizing the shape to the DecoPlanner schedule and cross checking it with the Ratio Deco method (which most people do in some form or fashion anyway --but is it still DecoPlanner?). . .

Exercises in rhetorical logic aside . . .what works, works!

 

[Bismark]

Try it Marc --a straight verbatim Decoplanner profile as crunched out by a computer for your hypothetical construct above . . .tell us if it works. Then try it again, tweaking/optimizing the shape to the DecoPlanner schedule and cross checking it with the Ratio Deco method (which most people do in some form or fashion anyway --but is it still DecoPlanner?). . .

Exercises in rhetorical logic aside . . .what works, works!

What exactly is your definition of "worked" here? As I understand it, you were bent on two separate occasions doing this. If that is correct, I don't think we can really say it worked. Am I mistaken about the facts here?

 

[Kevrumbo]

Wow --now I've been bent on two separate occasions? That's news to me. . . !

No . . .only acutely bent once requiring HBOT (hyperbaric oxygen treatment/therapy) in Truk's Hyperbaric Chamber, and then one more round of HBOT as a precautionary follow-up & three-day convalescence in Honolulu before returning to the mainland.

http://www.scubaboard.com/forums/near-misses-lessons-learned/264517-type-i-bends-hit-chuuk.html
http://www.scubaboard.com/forums/di...p-vein-thrombosis-status-post-dcs-type-i.html

The only objective conclusion you can draw from the incident regarding Ratio Deco (or any other deco algorithm) is that a 30% less than optimal deco profile leaves no room for error on the ascent. My buddy had a pefectly executed slowing ascent rate, right on the hairy edge --while I blasted-up to the surface like a Trident Ballistic Missile from around 3m in depth.

 

[MXGratefulDiver]

Yes Bob, I've done both on separate dives to 45meters --on Air and 21/35 -- same RD profile.
(And of course, I felt much better post-dive hours later after the trimix dive than the deep air)

Kevin ... that's your body talkin' to ya. Maybe those dives weren't as perfectly executed as you believe. As Uncle Pug used to say to me when he thought I was being a bit too aggressive ... "Maybe you ought to rethink your approach to that dive" ... (just a suggestion ... it's your body) ...

... Bob (Grateful Diver)

 

[Blackwood]

Try it Marc --a straight verbatim Decoplanner profile as crunched out by a computer for your hypothetical construct above . . .tell us if it works. Then try it again, tweaking/optimizing the shape to the DecoPlanner schedule and cross checking it with the Ratio Deco method (which most people do in some form or fashion anyway --but is it still DecoPlanner?). . .

Exercises in rhetorical logic aside . . .what works, works!

I agree that what works works, and I applaud your efforts to push the boundaries of existing decompression methodology (as Andrew did himself when establishing Ratio Deco). I'm not willing to take that risk, but I'm glad that some people are. More power to ya.

All I'm saying is that the term 'ratio deco' involves a specific set of standard gases, and if you don't use them, you aren't doing ratio deco (no more than you are doing ratio deco if you dive 21/35 with 50% deco mix but follow a schedule from Vplanner).

You're doing KeRumbo Deco

 

[Bismark]

Wow --now I've been bent on two separate occasions? That's news to me. . . !

No . . .only acutely bent once requiring HBOT (hyperbaric oxygen treatment/therapy) in Truk's Hyperbaric Chamber, and then one more round of HBOT as a precautionary follow-up & three-day convalescence in Honolulu before returning to the mainland.

http://www.scubaboard.com/forums/near-misses-lessons-learned/264517-type-i-bends-hit-chuuk.html
http://www.scubaboard.com/forums/di...p-vein-thrombosis-status-post-dcs-type-i.html

The only objective conclusion you can draw from the incident regarding Ratio Deco (or any other deco algorithm) is that a 30% less than optimal deco profile leaves no room for error on the ascent. My buddy had a pefectly executed slowing ascent rate, right on the hairy edge --while I blasted-up to the surface like a Trident Ballistic Missile from around 3m in depth.

From all the posts about your incident on various locations I misunderstood this as two separate trips to Truk, last year and the year before, and that you were bent on both trips. My mistake.

I am very curious as to why you continue to call your decompression strategy Ratio Deco even though I am pretty sure we have established via other sources, (UTD instructors, etc) that Ratio Deco is only intended to be used with standard gases of which air is not one of them. Or are you meaning you are using ratio deco (intentional lack of capitals)? Like I mentioned earlier, it may be entirely possible to construct a schedule that works in some fashion like RD for air, however, using the same numbers, intervals, etc that are used for helium which has markedly different on-gassing and out-gassing characteristics from N2 does not strike me as the way to do this. Your body and your choice though so this is up to you.

 

[Kevrumbo]

Fair enough guys . . .it's tough being a "documentary guinea pig".

I call it Ratio Deco Method because that's how I applied the algorithm per AG's monograph & PP presentation in the lecture/seminar taken two years ago. I came to the understanding that because of RD's (ie. Ratio Deco's) overall strategic conservatism and tactical profile shape for a trimix deco profile, the same application can be made to a deep air dive.

As an example, I derived the following simple table derived from RD on successful deep air dives during my Dec '07 Truk Trip:

Setpoint references: at setpoint 150'/45m for Ratio Deco 1:1 Schedule, my one 40cf Deco Bottle of eanx50% can safely cover a total deco profile time of 20 minutes given my deco stop DCR (Depth Consumption Rate). So my "insta-profile" depth & bottom time choices, using RD rules (i.e. adding 5min deco for every 10'/3m you go over the setpoint of 150'/45m), calculated out like this:

150'/45m for 20min;
160'/48m for 15min
170'/51m for 10min
180'/54m for 5min.
(Choose one of the above and stick to it for a square profile at the particular depth of interest)

The Deco Profile and time on Nitrox 50% is the same (20min) whichever depth and corresponding bottom time you choose above.