Ongoing discussion of Ratio Deco

[nereas]

Exactly. What I see is unwarranted faith in a methods that run on PC or Palmtop, and unwarranted suspicion of a method that uses your brain.


Tobin

Well, part of the adoption of a method is to field test it, gradually, and see how it works for you.

I think Max's post speaks directly to what would be warranted.

 

[rjchandler]

Perhaps actually having an understanding of ratio deco would be a good idea before posting crap like this. Also, an understanding of what kind of dives have been planned and executed with it day in and day out, and the reasoning behind it.

perhaps having a sense of humor would be a good idea before posting crap like this

 

[rjack321]

perhaps having a sense of humor would be a good idea before posting crap like this

Actually, I think Limeyx read it correctly or at least the same way I did.


Anyway, I have found ratio deco quite reliable. Total stop time is never less than 1 minute from decoplanner. Sometimes ratio is longer, particularly for O2 only deco.

Its not hard to use and the unintentional slip over NDLs is even easier (1:1 minutes over, exponential shape) to manage.

The only people who bash it are people who don't understand it. If you understand it and choose not to use it, that's fine. Sorta like doing NDL dives without a computer, I can understand how there might be hesitation there. But I don't see people who understand DOTF but not using it being very critical of it. Its the ignorant who are critical by and large.

 

[FishTaco]

Anyway, I have found ratio deco quite reliable. Total stop time is never less than 1 minute from decoplanner.

Really? This is not what I've observed.

The only people who bash it are people who don't understand it. If you understand it and choose not to use it, that's fine. But I don't see people who understand DOTF but not using it being very critical of it. Its the ignorant who are critical by and large.

Ratio deco may "work", but it's no substitute for real decompresion software. BTW, I do use ratio deco, however I don't blindly trust it.

Chris

 

[amascuba]

Really? This is not what I've observed.

Can you give an example? I'd like to have information such as dive profile, gases used, along with what you decided upon for deco based on DOTF please.

Ratio deco may "work", but it's no substitute for real decompresion software. BTW, I do use ratio deco, however I don't blindly trust it.

Chris

Nobody is saying that you should blindly trust Ratio Deco. Infact, I would go as far to say that if you are blindly trusting it then you don't understand the mechanics involved with Ratio Deco.

 

[rjack321]

Really? This is not what I've observed.

Time, depth, gases and GFs used please.

I want to see for myself how far "off" DOTF is. Be reasonable, no 8 hour exposures nor weird gases at unrealistic depths. 400ft on air anyone?

 

[FishTaco]

Time, depth, gases and GFs used please.

I want to see for myself how far "off" DOTF is. Be reasonable, no 8 hour exposures nor weird gases at unrealistic depths. 400ft on air anyone?

I don't have access to the program at the moment, But just run some common T1 profiles with 30/85 GF and compare for yourself.

Chris

 

[rjack321]

I have, and they are all pretty darned close. 21/35 or 18/45 (although Buhlmann has a penalty for extra He that I don't agree with) 50% for deco.

Sure the shapes are all "wrong" but total deco time for a 150ft dive with 50% deco is danged close.

Now doing a 50 min 100ft dive on 30/30 +O2 deco with proper DOTF deep stops will be alot more deco time overall than decoplanner. That I agree. However since there's no race to exit the water, I'm fine with that conservatism, which is mostly for the deep stops and only partially in the O2 time.

Since you seem to think there's a discrepancy between the 2 approaches, maybe you could give us a litle more info so we can see for ourselves, hmm? 'Cause I haven't seen any flaws.

 

[ScubaMilo]

Time, depth, gases and GFs used please.

I want to see for myself how far "off" DOTF is. Be reasonable, no 8 hour exposures nor weird gases at unrealistic depths. 400ft on air anyone?

Try 20min at 160fsw using 21/35 w/ean50
ratio deco says: 25min
d-plan(set at 30/85 GF) says:20min

and try

130fsw for 40 min using 21/35 w/ean50
ratio deco says: 30min
d-plan(set at 30/85 GF) says: 35

Neither is within 1 min as stated.
ratio deco seems to be inconsistent as to being conservative or liberal depending on the profile.

Hope this helps,
|Milo

 

[rjack321]

Isn't that what I said?

Anyway, I have found ratio deco quite reliable. Total stop time is never less than 1 minute from decoplanner. Sometimes ratio is longer, particularly for O2 only deco.

Let me try again since I guess this may have been misinterpreted...

Ratio is never more than 1 minute LESS than decoplanner. It may be more conservative. And you need to add it the deep stop times.