Modern Ratio Deco usage?

[_Ralph]

With no horse in the race I think I underestimate the powder keg topics.

Just saying that Ratio Deco <> Ratio Deco

Two different organizations tools to get out of the water, with two completely different methods with the same name ....


_R

 

[PfcAJ]

Typically it's a backup to tables (primary). Sometimes it's a backup to the tables and a computer. On standard-issue south Florida tech 1 dives in the 130-170' range in familiar enough with the tables that I can use RD as a primary tool.

But sometimes the length (or other parameters) of the dive outruns the parameters of ratio deco and it's not a consideration at all.

 

[kafkaland]

I checked secondary backup, although it's way down in the list of backups. Why use something that's by design a crude approximation to what computers can do much better? It feels like approximating sin(x) in your head with a polynomial, something you can certainly do, but would never ever consider doing if you had a calculator handy.

 

[CAPTAIN SINBAD]

UTD and GUE have totally different views on it. There are UTD divers who follow Ratio Deco on all dives including those where it deviates from every established algorithm and after hundreds of dives they can swear that they have not experienced any DCS symptoms. This has led them to believe that decompression is really not as simple to figure out as the mainstream dive industry believes and the risk you are taking while doing ratio deco is the same risk that you would be taking if you were religiously following a Buhlmann profile or bubble mechanics VPM etc. This crowd will follow Ratio Deco on all dive profiles and if and when they do get the bends they will gladly point at people who got bent following established algorithms too. To them it is not Ratio Deco that got them bent but "risks inherent to decompression diving no matter which profile you follow!"

I am personally not comfortable in following ratio deco outside of established algorithms so while I have some working understanding of Ratio Deco, I leave it at that. I would stick to Buhlmann and follow gradient factors so that I know what I am putting myself into. I am no expert but I believe that more research stands behind established models than what is generally shown to stand behind ratio deco.

 

[lowviz]

Typically it's a backup to tables ...//...

Now that finally makes a bit of sense to me.

What to do when my tables lock up...

 

[DevonDiver]

The vote is biased. Theres only a option for "I dont use it and feel it's dangerous"

There are many other reasons why divers might not elect to use RD, without feeling it's dangerous.

 

[PfcAJ]

Now that finally makes a bit of sense to me.

What to do when my tables lock up...

Or drop em, or if the dive plan shifts shallower or deeper.

 

[lowviz]

Fair enough.

You guys intrigue me, not enough to be a believer, but enough to keep watching...

 

[northernone]

The vote is biased. Theres only a option for "I dont use it and feel it's dangerous"

There are many other reasons why divers might not elect to use RD, without feeling it's dangerous.

Modified.

 

[sierrakilo]

In my first tec course with ISE (InnerSpace Explorers) a DIR-oriented, GUE offshoot I learned RD. I don't know which particular flavour of RD it was, as I understand from this thread that UTD and GUE do it differently. Perhaps a third flavour.

The ratio based profiles I would do previously, are less conservative than what I do now, using ZHL16 with GF. (not to mention RD start deeper)

Cheers,
SK