PADI tables finally going away?

[The Chairman]

And last time I checked some a couple agencies require computers and do not teach tables at all.

SDI encourages the use of a computer... but you can do the class on tables. Again, I would rather teach my students the vagaries of the equipment they will be using and not be held to teaching the far more mundane and confusing tables. I guess that's why I am an SDI instructor.

 

[DiveNav]

You are too deluded and dangerous for me to dive with my friend. ......

Calling me deluded and suffering surface narcosis sure sounds to me like an insult, not that I really care.

Pete & ZKY ...... com on ..... give me a break!

Have a beer on me.

Alberto

 

[DevonDiver]

I'm not referring to ZKY... but it does raise a decent issue (albeit slightly off-topic).

Being discerning about potential buddies..and refusing to dive with individuals you consider dangerous... is something that should be stressed in entry-level dive training.

Again...I am not referring to ZKY... but there are dangerous, careless, risk-taking, misinformed and deluded individuals within the diving community.

The capacity to spot them...and courage to refuse to enter the water with them....is the first step in responsible accident prevention.

Maybe if enough people did that...then these 'black sheep' would be forced to consider some self-analysis and re-appreciation of their diving methods.

 

[boulderjohn]

I would love to see the reaction Gary Gentile, Richie Kohler, or John Chatterton would dispaly if they showed up on a boat with no computer but did have analog gauges, a watch and tables and were told they could not do a dive..

Well, I don't know about Gentile, and I don't know about Kohler directly, but I know about Chatterton through his posts on ScubaBoard. Chatterton has participated in threads that discuss this very issue, and a search for them should be interesting. He would not show up with a computer. He would show up with 2 computers, and if Kohler were with him, he would count on Kohler having 2 as well.

I think we can be confident Gentile would not be there.

 

[miketsp]

Theres a side of the argument that no one has mentioned yet.

When diving tables, diver are cautioned not to dive a "square profile". I learned to dive with US navy tables and as part of the training it was understood that when used on a square profile (remaining at the max depth for the max NDL at that depth for the whole dive) the tables had a hit rather of about 1% and this rose to 4% for repetitive dives. As a result we added in fudge facotors - next deeper depth or next longer time on hard working or cold dives and next deeper depth and time on hard working and cold dives, etc. We also normally took care to avoid staying at the max depth for the whole dive and rounded up - a 61 ft dive always became a 70 ft dive.

When you look at multilevel tables (PADI Wheel, etc) or at a computer one of the first things you should notice is that the the NDL's are much shorter, even when compared to newer tables based on doppler ultra-sound, Bulhman tables, etc. The reason for this is that the computer calculates depth and compartment loading every few seconds, so every dive is in essence a "square profile" and the only way to add in a safety factor is to reduce the NDL's.

But what that means is that the responsibility for adding in a safety factor shifts from the diver to the computer - unless the diver also knows enough deco theory to understand the limitations and the factors a computer may not consider, such as how cold you are, how hard you are working, how much you drank last night, your hydration state, how many dives in a row you have been diving, etc.

In my opinion, that knowledge is vital to using a computer safely.

Could that hit rate be why tables based on US Navy tables suffered an adjustment around about 2000 to make them more conservative? My CMAS tables from the 90s are identical to US Navy original tables. My CMAS tables from 2002 are quite a lot more conservative.

 

[rstofer]

Not only do you revisit the tables for the PADI Nitrox course, I was just looking over the PADI Altitude course and... They're back!

It's going to be a bit of a challenge for my grandson as he did his OW using the eRDP. I'm not sure that you can specify an initial pressure group to the eRDP so it may not be useful for the Altitude course.

Yes, his computer does account for altitude. In fact, it automatically switches to fresh water when the altitude is over 1000 feet, something my NiTek Duo does not do. But the coursework still requires an RDP and correction tables.

Richard

 

[DA Aquamaster]

Could that hit rate be why tables based on US Navy tables suffered an adjustment around about 2000 to make them more conservative? My CMAS tables from the 90s are identical to US Navy original tables. My CMAS tables from 2002 are quite a lot more conservative.

I still have my original set of PADI tables and in the early 1990's I added a new line along the bottom indicating the new "doppler" limits based on doppler ultrasound research at the time. Most of the times moved back one increment (for example 60' for min became 60' for 50 min) and some moved back two or more, while the deeper deeper/shorter NDL's were largely unchanged. Those particular limits were widely publicized at the time and some agencies adopted modified tables based on those suggested limits.

The USN Navy has periodically revised their tables, but in a slightly different manner.

The PADI RDP has similarly conservative limits but is no longer a reformatted Navy table as it uses some different assumptions (such as a 6 hour out rather than a 12 hour out for offgassing).

 

[boulderjohn]

The PADI RDP has similarly conservative limits but is no longer a reformatted Navy table as it uses some different assumptions (such as a 6 hour out rather than a 12 hour out for offgassing).

Just some additional information on this topic for readers who may not have as much background as some posters:

When the Navy tables in existence at that time were created, they took Haldane's original compartments and added a 120 minute compartment, and they decided that the 120 minute compartment controlled the dive. That is why they have a 12 hour washout, as it takes 6 half times (6 X 120) to clear that compartment (98.5% clear, actually).

The doppler bubble imaging work that led to the RDP determined that for no decompression (recreational) diving, the 40 minute compartment actually controlled the dive. They decided to be more conservative and selected the 60 minute compartment as the basis for the RDP. Thus you have a 6 X 60, or 6 hour washout.

The result is that in following the RDP, the recreational diver does not have to wait as long during a surface interval as someone following the Navy tables.

 

[muddiver]

Fair points, but....

When a new computer user reads their manual (we all do right?).... they will see that they are recommended to use the in-built computer conservatism settings in the event of certain diving situations (cold water. exertion etc).

So, instead of planning "one depth level deeper" on a table, they just blip the appropriate button onto the appropriate setting of conservatism.

Same effect and, as alway'...easier to do on a computer than tables....

Ok, I'm sitting here with my Oceanic DataMax Sport, read the manual, can you tell me how to set the conservatism?

 

[stadevene]

There's a recent thread in A & I which gives a good example of why knowing tables is important.

http://www.scubaboard.com/forums/ne...rned/299561-long-deco-incident-last-week.html

Personally, while I have a computer, I still run the tables. It's actually fun.