Why do some agencies recommend using a bottom timer instead of a computer

[Dan_P]

Friends I know. FRIENDS I KNOW. You want me to list names? Most are pretty embarrassed about what happened (simple math problem), a few are in denial about it and all would feel that I've betrayed them were I to divulge their names. Two are posting in this thread, one on either side of the discussion.

Ratio Deco is not the Holy Grail of diving. It does not grant the user a penultimate understanding of deco and full control of their DCS destiny. Again: WHAT'S THE BENEFIT? I have gone diving, many times into deco for almost 49 years without it. Unless you can prove it's significantly safer (good luck with that) or that it will bring me a cold beer after I finish diving, I don't see a need to waste cognitive resources learning it or using it on a dive.

Friends don't let friends dive Ratio Deco.

Now, someone brings up that there's a difference between two types of Ratio Deco. Again, what's the benefit? Where's the study that shows me it's safer than my Shearwaters or my Garmin Descent? Show me how it's safer than my first PDC: my Orca Skinny Dipper. I never got bent off of that either.

To a worm in horseradish, the world is horseradish.

The problem is you're saying RD is dangerous. You can't then call for proof that it's safer than whichever computer.
Rather, you ought to provide basis for your litigations.

Reversely, I wouldn't claim Shearwaters to be a death trap, because there is no basis to support such a claim.

But you're claiming that RD is dangerous, and "Friends don't let friends dive Ratio Deco", so you're expectably called upon to support your claim.
My opinion of the preliminary retort you have chosen to offer here, is that it appears subjective.

In summary;
1) I say I see practical benefits to a standardized deco paradigm.
2) You have shown, and admitted, that you don't know the details of a such deco paradigm, so you can't speak of any such benefits.
3) You call a standardized deco paradigm dangerous.
4) When prompted for substantiation to that claim, you simply reiterate your unawareness of the benefits mentioned prior.
5) I say to a worm in horseradish, the world is horseradish, implying solely subjectivity to the matter at hand (I wish to be clear on that)

This here, however, is probably the smartest thing I've seen said in this whole conversation, though:

Ratio Deco is not the Holy Grail of diving

Indeed it is not!

I would prompt divers preoccupied with holy grails to stop preoccupying themselves with holy grails. No such thing exists.
Only cups and water dispensers.
This whole debate is about clarifying the confusion that a cup does not equal a water dispenser, and neither is a holy grail.
They're all different.

So are a standardized deco paradigm and an algorithm.
And a claim that any one such is dangerous, should be substantiated.

 

[The Chairman]

The problem is you're saying RD is dangerous.

Horseradish! I said that I know too many divers who have gotten bent on Ratio Deco and have no desire to follow in their footsteps. However, friends don't let friends dive Ratio Deco.

You can't then call for proof that it's safer than whichever computer.

Why not? Show me equivalency or that it's better. Why would I abandon what I'm using just to make you feel superior? You claim it's better: show me.

so you're expectably called upon you to support your claim.

And I've supported it with personal observation. You don't get to dismiss that because it's an inconvenient truth. Denial might work in politics, but it's a poor protocol for a scientific understanding.

I say I see practical benefits to a standardized deco paradigm.

Wow. What a spin. No, you claim "practical benefits" for Ratio Deco and haven't shown a single one. I keep asking what are the benefits and you never answer that question.

You call a standardized deco paradigm dangerous.

Please quote where I typed that. I triple dog dare you.

And a claim that any one such is dangerous, should be substantiated.

And a claim that one has "benefits" should be substanstiated.

You're free to climb out of that horseradish at any time.

 

[Dan_P]

In summary;
1) I say I see practical benefits to a standardized deco paradigm.
2) You have shown, and admitted, that you don't know the details of a such deco paradigm, so you can't speak of any such benefits.
3) You call a standardized deco paradigm dangerous.
4) When prompted for substantiation to that claim, you simply reiterate your unawareness of the benefits mentioned prior.
5) I say to a worm in horseradish, the world is horseradish, implying solely subjectivity to the matter at hand (I wish to be clear on that)

You call a standardized deco paradigm dangerous.

Please quote where I typed that. I triple dog dare you.

Why the f@#$ does Ratio Deco account for such an inordinate number of DCS incidents?

Friends don't let friends dive Ratio Deco.

But you're claiming that RD is dangerous, and "Friends don't let friends dive Ratio Deco", so you're expectably called upon you to support your claim.

The problem is you're saying RD is dangerous. You can't then call for proof that it's safer than whichever computer.
Rather, you ought to provide basis for your litigations.

Why not? Show me equivalency or that it's better. Why would I abandon what I'm using just to make you feel superior? You claim it's better: show me.

I've claimed it to have practical benefits, you've claimed it to be dangerous.
Where have I claimed RD to be more optimal in terms of the physiological decopression process?

I say I haven't. You seem to say (wrongfully) that I have. Do you stand by that?

Wow. What a spin. No, you claim "practical benefits" for Ratio Deco and haven't shown a single one. I keep asking what are the benefits and you never answer that question.

And a claim that one has "benefits" should be substanstiated.

And I've supported it with personal observation. You don't get to dismiss that because it's an inconvenient truth. Denial might work in politics, but it's a poor protocol for a scientific understanding.

So "The Chairman says so" is your scientific evidence, and what, anyone disagreeing are part of a personal cult?

The problem is you're saying RD is dangerous, but you can't support your claim.

I, in turn, find that RD or a standardized deco paradigm is practical because of the easy logistics, including in blending, the uniform decompression across systems, the growing recognition and increasing intuitive understanding of ratios across time and deco and the potential to test and develop divers' ability to think while diving - you can try to argue whether or not I feel that way, or you can actually try to support your own statements:

What is your support/basis for calling RD dangerous?

 

[The Chairman]

I've claimed it to have practical benefits,

Just what are those benefits??? I keep asking. You keep not telling.

 

[LiteHedded]

If you have a smart phone and a petrel, IMO the benefits are slim to none

 

[Dan_P]

@The Chairman you really should start reading what's written before you kick off.

I've been PERFECTLY clear that I'm not stating RD to be more optimal in terms of the physiological decompression process.
Here is a quick answer regarding some practical benefits that I see, repeated from my post above:

So "The Chairman says so" is your scientific evidence, and what, anyone disagreeing are part of a personal cult?

The problem is you're saying RD is dangerous, but you can't support your claim.

I, in turn, find that RD or a standardized deco paradigm is practical because of the easy logistics, including in blending, the uniform decompression across systems, the growing recognition and increasing intuitive understanding of ratios across time and deco and the potential to test and develop divers' ability to think while diving - you can try to argue whether or not I feel that way, or you can actually try to support your own statements:

What is your support/basis for calling RD dangerous?

You're claiming RD to be dangerous.
I've asked you to support that claim.
You're failing to present support of your claim.

I'm prone to believing that's because no evidence exists to support your claims, and what you're saying is built on subjective narrative - unless you actually have something of substance to present?

 

[Dr Simon Mitchell]

Dan,

I think you are being a little disingenuous in purposively focussing your defence of UTD-RD on opposing claims that "it is dangerous". That is a great platform for you because you are well aware no-one could substantiate such a claim on the basis of existing data. However, it would be a little more honest to admit, from time to time, that there are published data demonstrating that UTD-RD is not the most efficient physiological approach to decompression. Therefore, depending on how you define "dangerous" (eg associated with a significantly higher risk of DCS than other approaches of similar length), those existing data certainly raise the possibility that it could be "dangerous"; we just don't presently have the data to make such a judgement.

Simon M

 

[Dan_P]

Dan,

I think you are being a little disingenuous in purposively focussing your defence of UTD-RD on opposing claimsthat "it is dangerous". That is a great platform for you because you are well aware no-one could substantiate such a claim on the basis of existing data. However, it would be a little more honest to admit, from time to time, that there are published data demonstrating that UTD-RD is not the most efficient physiological approach to decompression. Therefore, depending on how you define "dangerous" (eg associated with a significantly higher risk of DCS than other approaches of similar length), those existing data certainly raise the possibility that it could be "dangerous"; we just don't presently have the data to make such a judgement.

Simon M

Hi Simon,

As well indeed I do -
(admit, from time to time, that there are published data demonstrating that UTD-RD is not the most efficient physiological approach to decompression) - at least in the case of RD1.0.

That's not the point of contention here, however.

This string took a turn well beyond the scope of the nuances you're expressing and which are usually discussed in terms of what the "optimal" deep stop emphasis may be;

When it crossed into the realm of "friends don't let friends dive Ratio Deco", I think it's more than fair to object.
I don't think there's anything disengenious about such an objection, nor anything controversial.

I don't mean for the following to be a slander or belittlement of anyone, but from my admittedly limited third-hand understanding, "friends don't let friends dive Ratio Deco" appears to have evolved from a single sample of divers (let's refer to it here as Tordenskiold's Soldiers) who reportedly experienced a disproportionate occurance of negative outcomes while using RD, compared to general population.

I propose it's reasonable to assume that factors hadn't been isolated in such a sample.
That equating those outcomes to RD efficiency in general, would be unacceptable.

While I have no first-hand knowledge about the case in question, we're apparently talking diving one might call on NASA for consultancy on, carried out by divers who reportedly struggled to keep track of max depths/times, maintain ascend rates, maintain depths during stops and carry out simple arithmetics.

Is it your genuine position that I'm being disingenious for defending RD from "friends don't let friends dive Ratio Deco" on such a basis?

I'd like to reiterate that this is not me stating anything to the effect of supremacy in the physiological decompression process whilst using RD, rather me objecting to "friends don't let friends dive Ratio Deco" and similar comments.


Best Regards,

Dan

 

[Dr Simon Mitchell]

Is it your genuine position that I'm being disingenious for defending RD from "friends don't let friends dive Ratio Deco" on such a background?

Hello Dan,

"Friends don't let friends dive RD" and "RD is dangerous" are comments cut from approximately the same cloth. I don't blame you for pointing out the obvious, which I do too in my post above. BUT at the same time, the most honest, accurate, and complete appraisal is the one I also present above. You, on the other hand, invariably stop with simply saying "you have no data to support that statement" without ever quite admitting what the extant data could imply.

Simon

 

[Dan_P]

Hello Dan,

"Friends don't let friends dive RD" and "RD is dangerous" are comments cut from approximately the same cloth. I don't blame you for pointing out the obvious, which I do too in my post above. BUT at the same time, the most honest, accurate, and complete appraisal is the one I also present above. You, on the other hand, invariably stop with simply saying "you have no data to support that statement" without ever quite admitting what the extant data could imply.

Simon

Hi Simon,

Agreed.
But that's not to say that I'm trying to represent room for further research as any measure of probability that RD has an 'optimal' emphasis on deep stops.

That said, I am purposely trying not to deal in, or phrase myself in, absolutes;
E.g. I don't believe the "optimal" algorithm (whichever it will turn out to be) will make decompressing "safe", and I don't believe that deviating from such an algorithm could necessarily be described as significantly more "unsafe".
I also don't believe that an "optimal" algorithm will be identical across all persons (the current theme of my extracorrigular pursuits is a hypothesis that if bubble-induced platelet aggregation accounts for lacking benefitial results on bubble propagation from deep stops, namely due to CCL5/rantes, and CCL5 activation is genetically dispositioned, then optimal deep stop emphasis could be said to be genetically determined on the individual level, at least to some extent, by a metric involved in that response).

Yet another sidenote, that.


Best Regards,

Dan