Place of dive tables in modern diving (Split from the basic thread)

[CAPTAIN SINBAD]

It's a strategy to be 'different' and look cool to everyone else using this fraudulent system. That's my opinion and I have seen no real science to change my mind. In fact, in talking with DAN behind the scenes, they don't like it either. While the rest us, following tables or PDCs get bent so rarely as to DAN referring to these incidents as being mere "noise", it's not so with ratio deco divers. They get bent to the point of it being alarming to DAN.

To quote the venerable Dick Rutkowski who popularized NitrOx: "Science over Bullshite". If you can't produce the science, then don't feed me the BS.

To put this in perspective, I know of only 4 people who got bent diving within their NDLs. All of them were on Ratio Deco. All of them. None of them blame ratio deco... they blame themselves for not averaging correctly, making mental mistakes and what not. This is why PDCs are so good. They never get distracted from their one job of making sure you're not a DCS statistic. Within NDLs, they are amazingly effective. Get into deco and especially multiple days of deco and then things start to slide a bit. But not nearly as bad as Ratio Deco. I love you Kev, but that RD crap scares the bejesus out of me. I won't go there. I won't.

What I find interesting is that if you sit with the UTD community, they think that you and I are trying to look "cool" with our Perdix and Air integration computers etc. In their mind, theirs is the less glamorous and more practical style of diving than ours. We are the show offs! Outside UTD/DIR people tend to think that it is the DIR people who are trying to be "cool" (kool aid drinkers).

I like to be open minded. Presently there are four ways you can plan a dive.

1) Computers
2) Tables
3) Desktop software
4) Ratio Deco

Each of these have advantages in specific situations as well as disadvantages in specific situations. I think all of these add value to the other but I am not convinced that any of these really "replaces" the other. I also think that in order for form any opinion on any of the above, you really have to spend at least 10 dives diving with that particular method. It is only when you develop equal comfort / proficiency level with all of these that you can then be objective about which is more prone to "user errors."

 

[CAPTAIN SINBAD]

When people say that folks are getting bent on ratio deco then we need to be more specific. There are three different groups who use the term ratio deco.

a) First is GUE who use it as a back up. In case they ever used it then I would assume they were amidst a catastrophic situation and if RD was used then they got out with relatively less symptoms than they would have if they had not relied on RD. This is the use of RD when $h!t has hit the roof!

b) UTD is the second category. Unlike GUE they use Ratio Deco as a strategy which used to incorporate theories (like oxygen window and S curve) that were not part of any algorithm but were making the ascent safer than a pure algorithm (at least in their minds). Nowadays UTD RD it is starting to look more like a Buhlmann profile since a lot of stuff on which UTD RD was based was found to be unnecessary and even riskier in the UTD Italian study.

c) Self tutored RD experts: These are people who have no formal training in Ratio Deco. They have figured out relationship between bottom time and deco times and are eager to execute them without cross referencing the risk against any established algorithm. I have never met any of these in person but while wandering on various internet forums, I have seen discussions that are quite shocking and it makes me wonder if these guys are really going out and doing what they believe to be "ratio deco" then I am sure there will be DCS incidents. So when DAN collects incidents caused by Ratio Deco, all of the above would get classified into one single category which will then get classified as "high risk." When DAN or anyone else says "people have been bent on RD" then a more accurate data analysis is needed in terms of what they are calling as RD and if someone has some real figures with more accurate classification then I would really like to see those.

 

[AfterDark]

On multilevel recreational dives when you don't know what your times will be at different depths because you do not know what you are going to see, the difference is often many multiples of 5 minutes. The difference is "I can go look at that shark" instead of "I don't dare go below my current depth".

Great but that's not what I was thinking. When I'm planning my next dive I compare what the PDC tells me my max BT will be to what I cipher from the tables. That's usually a difference of abt 5mins. However on this hypothetical next dive the BT is near and, providing I haven't been playing the depth/time game, lets say my PDC gives me a LOT more additional BT than the table did, than my reaction is the PDC has failed and I surface at the tables times. However if it's say 5 more minutes then I'll take it! The other scenario would be if I'm using my 2nd PDC and it does not agree with the 1st by a wide margin than the lesser of the two wins. Works for me as they say!

 

[dmaziuk]

Great but that's not what I was thinking. When I'm planning my next dive I compare what the PDC tells me my max BT will be to what I cipher from the tables. That's usually a difference of abt 5mins. However on this hypothetical next dive the BT is near and, providing I haven't been playing the depth/time game, lets say my PDC gives me a LOT more additional BT than the table did, than my reaction is the PDC has failed and I surface at the tables times.

This works on day 1 and/or if you're using DSAT tables and DSAT PDC. Otherwise by day 3 or 4 your PDC should be giving you less BT than the table did -- what's your reaction gonna be? That the table has failed?

 

[oldschoolto]

I guess some people are happy to ride their PDC at the least conservative setting and push the dive times to the last minute... Have Fun..... It's not for me.. I can't think of going to Bonaire to make 4-5-6 dives a day and feel like hell when I get home.. But maybe I'm just old...

I like to drink a Brite, Cook a lionfish on the grill and then a good helping of Nookie after... I'm lucky if we get out of the house by 10:00 AM....

Jim.....

 

[CT-Rich]

Each of these have advantages in specific situations as well as disadvantages in specific situations. I think all of these add value to the other but I am not convinced that any of these really "replaces" the other. I also think that in order for form any opinion on any of the above, you really have to spend at least 10 dives diving with that particular method. It is only when you develop equal comfort / proficiency level with all of these that you can then be objective about which is more prone to "user errors."

I think th concern is that if I were to do 10 dives using RD I would get bent and then be told “Of course you got bent, you only did ten dives with it. If you coul show with other models that you won’t get bent using RD, you might have something, but I am yet to hear anything that definitively validates this type of diving. Properly used PDCs and tables get people to the surface safely. While I have not read up extensively on RD, I am yet to hear anything that woul show by a previously accepted method that it is better or safer than other methods.

 

[The Chairman]

Properly used PDCs and tables get people to the surface safely.

Which makes one wonder why they want to reinvent the wheel (or RDP) without any science to back it up?

 

[PfcAJ]

ITT: people opining on ratio deco that don’t understand ratio deco.

 

[Kevrumbo]

I think th concern is that if I were to do 10 dives using RD I would get bent and then be told “Of course you got bent, you only did ten dives with it. If you coul show with other models that you won’t get bent using RD, you might have something, but I am yet to hear anything that definitively validates this type of diving. Properly used PDCs and tables get people to the surface safely. While I have not read up extensively on RD, I am yet to hear anything that woul show by a previously accepted method that it is better or safer than other methods.

IMO, problem is if you did the typical liveaboard week-long itinerary of 3 to 5 repetitive dives per day on Air or Nitrox right up to NDL, you will have a significant slow tissue inert load by day 5 on any particular model PDC or Table algorithm, and therefore subject to the same increased risk of DCI. . .

 

[The Chairman]

right up to NDL

Why would you do this? That's just abusing your body and the algorithms. I've done many a liveaboard and have yet to be bent. That's no accident.