Place of dive tables in modern diving

[tursiops]

I was certified in 2013, so my information may not be valid, but looking at your story, it seems to me that the Dive Op, broke one of the Diving rules when diving with a computer. The big one being never dive on someone else's computer.

Although this is no fault of your own, I might consider checking things out before you go to use a rented computer - to avoid situations like this in the future. It also brings in the importance of having something like this - that is your own.

Secondly, when I was certified, I got trained on PADI's electronic device that had the tables in it (ERPDML??), but I also had a computer book, so I guess I got the best of both worlds....

LOL! That is the first time I've ever heard the eRDPML being in the category of the best of ANY world!

 

[Bubblesong]

A dive shop gave my daughter a Dive computer that was embedded in a console on rented reg. And was in “lockout mode” from previous Diver, But we dive tables and had our own DIve computers, so we ignored it. But if we’d needed it, there was little time to check it out and learn to use it between rental counter and diving.

 

[scubadada]

I was first certified in 1970 by LA County, we used USN tables. I was recerified with my 12 year old son in 1997 by PADI, we used PADI (DSAT) tables. I was nitrox certified in 2002 by PADI, we used PADI nitrox tables. I bought my first computer in 2002 and have not used tables since. Personally, I'm glad I had considerable experience with tables, it made it extremely easy for me to transition to a computer and to have a good idea of how it worked. I now have a good amount of knowledge and experience with dive computers.

I have no problem with new divers not being taught dive tables, as long as they receive sufficient information to have a solid understanding of how dive computers work.

 

[Bob DBF]

In 2008 the Navy Dive manual was revised and tables still had 60' at 60 min
http://www.usu.edu/scuba/navy_manual6.pdf#page498

The 120 rule was good in the 1960's from 60' to 90', above or below that it was conservative. In 2008 USN dive table 70' was 2 min over. 80' was 1 min over, and the rest was the same as back in the 60's.

I used the US Navy dive tables from 62 until I got a computer around 2006 or something. They are still in my head for sanity checks. As they say about computers, pick the algorithm you want. Since I haven't had an issue with the dive tables as I originally learned them, that's what makes sense to me. The computer is more conservative and I have no issue with following it's limits.

Torsiops is right in the fact that modern tables have evolved (PDIC alowing 51 minutes at 60ft) so it would be good to learn the "110" rule instead.

Depends on the tables you use, same as computers.
http://www.navsea.navy.mil/Portals/103/Documents/SUPSALV/Diving/US DIVING MANUAL_REV7.pdf?ver=2017-01-11-102354-393



Bob

 

[tursiops]

I have no problem with new divers not being taught dive tables, as long as they receive sufficient information to have a solid understanding of how dive computers work.

This is really the point. If they are going to use a dive computer, there is a minimal level of understanding they need. Perhaps tables will help them gain that; I doubt teaching tables and then computers is the efficient way to get get someone to understand computers.

 

[scubadada]

A dive shop gave my daughter a Dive computer that was embedded in a console on rented reg. And was in “lockout mode” from previous Diver, But we dive tables and had our own DIve computers, so we ignored it. But if we’d needed it, there was little time to check it out and learn to use it between rental counter and diving.

On more than several occassions, I have been asked by divers why their computer is are not working normally. They generally had no clue to what I was talking about when I told them it was in violation gauge mode

 

[boulderjohn]

On more than several occassions, I have been asked by divers why their computer is are not working normally. They generally had no clue to what I was talking about when I told them it was in violation gauge mode

I learned to dive about 20 years ago. On my first dive trip, I followed the Cozumel DM on a multi-level dive and found I could not use those tables for those dives. I got a computer. That time I pulled out the dive tables and realized they were useless for the diving I was doing remains the first, last, and only time I have ever seen anyone attempt to use tables for a recreational dive.

So for decades we diligently taught students how to use tables, knowing full well they would then go out and use computers instead, and they would do that with no training on how to use them. Is it any wonder that people who were given no training on computers don't know how to use them?

 

[kelemvor]

In the spirit on not hijacking another thread I thought I should take start this discussion from a fresh page. The event that I am describing below is true though my memory of depth and bottom time numbers that I state below may be off since this happened in 2008 and I was a new diver.

I got certified to dive in the year 2004. Dive computers were not very common and my whole class was trained to dive using dive tables. Everyone in the class knew the set point of 60 by 60. For the first dive of the day, 60/60 would be the start of our No decompression limit calculations. We knew that if the dive depth had not exceeded 60 feet then our bottom time could easily be 60 minutes. It was really that simple! Then, for 70 feet we would have a bottom time of 50 and for 80 it would be 40. The above depth and time limits were ingrained into our minds and we would remember them like we would remember our mothers name. This meant that for the first dive of the day, no one needed to even look at tables. We knew the available dive time for each depth from pure memory. It was for the second dive that dive tables were pulled out and and adjusted no-decompression limit were read, noted down on a slate and then we jumped in.

This was diving for me in the early 2000s. Then I stayed out of water for many years until I returned back to diving in 2008. Between the years of 2004 to 2008 the computer revolution happened and dive computers went from being a luxury item to a mandatory item on many dive operations. Upon my return to diving, I signed up to dive a wreck which was resting at 130 feet while the top was 50'ish. The dive operation insisted that since this wreck has many decks and different people are interested in exploring different depths, everyone should have a dive computer. I had not used a dive computer up until then and did not feel the need for it but the dive operator said that computers are mandatory on this dive. I ended up renting one.

This was the second charter of the day and the dive computer that I was given had already been used by a diver who was on the first charter and had done two dives on the same wreck with that computer. The dive operator gave me the computer without resetting it and I ended up wearing a computer that believed that the dive I was about to do would be my THIRD DIVE of the day. I was told by the dive operator that the computer will activate itself at 5 feet depth so just go and dive mate! When we splashed and I reached the top of the wreck at 60, I knew from the table ingrained in my memory that I should have 60 minutes at least. The computer was giving much less than that. I knew right away that this device is dead wrong but I did not know why. There were two things about the computer that were correct though. Depth and bottom time. As a table diver, that is all I needed to complete the dive. During the dive, I exceeded the projected no decompression limit which would have applied to the fellow who wore the computer before me. I ignored the warnings and proceeded to dive my no decompression limit from memory. When I surfaced, all alarms were going off and I knew that they were wrong. The dive boat went into panic mode because a diver just surfaced with warnings beeping on the computer!

The dive master looked at the computer and said that I had gone deep into decompression and I needed to be checked for symptoms. He started to run a decompression diagnosis on me while the deck hand was preparing to put me on 100% oxygen. I tried to explain to them that I can’t be in decompression because my depth was less than 70 and my bottom time was less than 50. Any diver knowing tables would know that the numbers I am stating mean that I was safe but behold ... the computer revolution had started and the age of electronic stupidity had begun. In this age it was not only possible to become a certified diver without knowing dive tables but was also possible to become a divemaster and lead dives without knowing depth and table limits. When computer said you were surfaced while in deco, all dive theory and basic common sense was abandoned and 100 percent oxygen was to be given.

Fortunately, other people began to surface from the dive. One of these was a dinosaur from the pre-historic era. He had been diving since the earth was very young and there were no dive computers. He saw all the chaos and asked me two questions. "How deep were you?" and "what was your bottom time?" I was relieved to see that someone spoke the same language instead of "What is your computer saying?". He told the DM that there must be something wrong with the computer because 70 feet and less than 50 minutes is really not an emergency. He kept asking me “Are you sure about your max depth and bottom time?” I told him yes. Then they all began to fiddle with the computer and it turned out that I was right and the computer was wrong! Since data from the previous dive had not been deleted, the computer calculated it to be my "third dive." The guy before me had taken the computer really really deep so the computer was seriously freaking out on this “third dive.” The confusion did not last very long and life went back to normal but had the dinosaur from the prehistoric age not emerged from the ocean then I this “lets follow the computer crowd" would have put me on pure oxygen or I would be getting evacuated by a helicopter to the nearest decompression chamber.

Today there are agencies that train you to dive on computers from day one and they are proud of it. It is seen as a sign of embracing tomorrow and being progressive. The questions is not whether computers are good or bad but whether we are using the computer to advance our thought or whether we are using it to think for us? Furthermore what is wrong in using a multiple tool approach to planning dives? Diving courses of today are loaded with so much nonsense (boat dive specialty, shore dive specialty, put your mask on specialty, take your own fins off specialty) what is wrong with creating divers who are as proficient on tables as they are on computers?

Thoughts?

It sounds to me like diving a computer you did not know how to operate was the real problem. I don't think that story says anything at all about dive computers vs tables other than this. Whichever tool you choose, you need to know how to use it.

 

[lowviz]

...//... The questions is not whether computers are good or bad but whether we are using the computer to advance our thought or whether we are using it to think for us? ... Thoughts?

I posted in the other thread but didn't pursue the thought as it was off-topic. Here, it can be continued.

My OW instructor stated: "For our OW instructional diving, the table that I'm giving you is effectively the same thing as that which is in your computer". His experience was that an OW DC class degenerates into a beep-fest of three to four different DCs with everyone looking at the odd computer that his/her neighbor is fussing with. Basic understanding is totally lost in the confusion. 'We'll get your DCs squared away tomorrow, but for now, let's understand what is going on."

He examined a rectangular dive profile and showed how tables worked rather well, even for a few repetitive dives. He then examined a shore entry profile and showed how tables sucked. But you can cut your dive into segments as long as you can keep track of the loading from the earlier segments. Forget it, that's why we have DCs.

Tables are great training wheels for understanding your DC.

 

[tursiops]

Depends on the tables you use, same as computers.
http://www.navsea.navy.mil/Portals/103/Documents/SUPSALV/Diving/US DIVING MANUAL_REV7.pdf?ver=2017-01-11-102354-393

Interesting point. the whole "Rule of XXX" was based on the sum of depth (in feet) and NDL (in minutes), which turned out to be 120 for the old Navy tables, between 60 and 90 ft. For shallower depths, or deeper depths, the 120 rule was quite conservative...for example it would suggest 10 minutes at 110 ft and zero minutes at 120 ft, whereas the actual table gave 20 and 15 minutes, respectively, at 110 and 120 ft. So, the rule of 120 kept you "safe." On the first dive, only. It was even printed on the watchbands of the day:

This same "Rule of XXX" could be applied to pretty much any dive table or dive computer, for the first dive. Find that depth at which the sum of depth and time is the minimum, and that is your new rule. The PADI RDP gives 110, valid for 70 and feet; at any other depth the Rule of 110 is conservative. For 32% Nitrox, the PADI RDP rule would be 125, 'exact" for depths of 80 and 90 ft, conservative for any other depth.

The newest Navy table, linked above, would have a Rule of 118, "exact" at 70 ft, conservative at any other depth.
DCIEM would have a Rule of 105.
My old DiveRite DUO would have a Rule of 104.
My old DiveRite PLUS would have a Rule of 106.
My old Zeagle N2Ition 3 would have a Rule of 105.
My Oceanic OC1 (DSAT) has a Rule of 110, just like the PADI RDP. Surprise!
My Oceanic OC1 (PZ+) has a Rule of 105.
My Shearwater in Rec Mode with Low Conservatism (GF 45/95),Rule of 105.
My Shearwater in Rec Mode with Med Conservatism (40/85),Rule of 98..
My Shearwater in Rec Mode with High Conservatism (35/75),Rule of 92.
My Shearwater in Tec Mode with GF 30/60, Rule of 81.
My Shearwater in Tec Mode with GF 30/70, Rule of 89.
My Shearwater in Tec Mode with GF 20/80, Rule of 96.
My Shearwater in Tec Mode with GF 49/99, Rule of 109.