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scubastud
04-12-2010, 09:40
I have been seeing this or something like this advertised .

"Get open water certified. Package includes dive computers, so no need to worry about dive tables!"

If you are new to diving, I would advise you to steer away from this type of attitude.

Just me two bits.

rayaa3
04-12-2010, 09:46
While I haven't seen it advertised exactly that way - yes, one of our local padi shops now teaches on computers, and I don't believe that table work is part of the final exam anymore.

I agree with you. It's sort of the calculator/math thing. Everyone should know how to use a calculator, and everyone should know how to do math on paper. I'm not saying that OW can't be taught with computers. In fact, I think it's great. I think however, that table diving should still be taught, and those skills should be required as part of your exam.

Hell, it might even be an excellent exercize for a beginner to dive with a computer, then figure out their no decompression limits with a 2nd dive using the tables, compare it to the computer, and discuss why the computer may be more (multilevel calculations).

At anyrate - I agree with you.

Foo2
04-12-2010, 09:53
I think it's pretty lame to not teach tables. What if your computer fails? Then you're done diving for the day whether you like it or not. Not to mention a computer isn't always the first thing that you run out and buy after you are certified. Tables are free!

brojack17
04-12-2010, 09:56
That's a tough one. I remember during Calculus in college the professor would spend 1/2 hour explaining how to do something and us working hard on it. When we finally got it, he would say, "ok, here's the short way to do that". Why not just teach the short method and show one example of how that theorem is proven.

It's a little different with the tables. Not every piece of gear has computers. What happens when one of these people go on a vacation and dive with rental gear. I doubt the rental gear has computers.

I still see this as a valuable skill to know.

DivingCRNA
04-12-2010, 10:04
If they ever take Tec, they will need to know the table theory. Even though planning software gets used a lot, it is good to know how it works.

bassplayer
04-12-2010, 10:13
My first tendancy is to say no way, everyone should learn tables because that is how I was taught and I found it to be a good way of understanding gas laws. However as I get older I find I am always saying things like, remember when bread was 25 cents...etc

If you take the way I was trained in the 70's as the standard today, there would be fewer divers out there. Perhaps we should embrace new technologies that have been proven. With regards to tec...perhaps the computers are just not there yet...give em another ten years and who knows?

So new divers only know how to dive with a computer....does it really matter? Forgot to bring your regulator....no diving today. No computer no diving today...

plot
04-12-2010, 10:19
Agencies are moving towards not teaching tables, because lets face it, most people use a computer anyways, most dives are multilevel so they want more bottom time, and computers are a whole lot safer. Yes, I said computers are safer. More people have died from bad math than a malfunctioning computer. Depth guages and SPG's can break just as easily as a computer, so some common sense has to come into play either way if a peice of gear is malfunctioning, and when you realize it, you thumb the dive. (If you're 45 minutes into a dive and think you're all of a sudden a super diver because you've only used 200lbs of air... well...).

Not to mention, if you DO screw up, blow your NDL's, your computer will tell you what to do to fix it... will beep at you when you're low on air, etc.. give you a ton of prewarning signs that can be extremely beneficial to a new diver.


I think it's pretty lame to not teach tables. What if your computer fails? Then you're done diving for the day whether you like it or not. Not to mention a computer isn't always the first thing that you run out and buy after you are certified. Tables are free!

Some of us use two computers in case one fails when planning mutliple dives for a day. :smiley2:



It's a little different with the tables. Not every piece of gear has computers. What happens when one of these people go on a vacation and dive with rental gear. I doubt the rental gear has computers.

I still see this as a valuable skill to know.

Computers are becoming a whole lot more prevalent everywhere, it's another way for them to rent one more peice of equipment to you by stating it's mandatory dive equipment. On resort dives, most people probably don't figure out their tables anyways, they rely on following their guide. When this is the case, computers add another level of safety.

Tables just arn't neccessary for the typical recreational resort diver who may get in 6 dives a year on vacation. It takes up a lot of classroom time that could better be spent on something they're more likely to need underwater.

Rorschach
04-12-2010, 12:03
I think it's pretty lame to not teach tables. What if your computer fails? Then you're done diving for the day whether you like it or not. Not to mention a computer isn't always the first thing that you run out and buy after you are certified. Tables are free!

Redundant computers can be a wise investment, especially pre-owned computers. A one-time investment of about $200 or so for the many dive trips to take.

This was also the only option when the Bikini Atoll divers were in operation that didn't require a bunch of bail-out options (although it was best if both computers were two-mix Nitrox capable and from their "Recommended - Proven to Work on Bikini" list).

Message from the Head Divemaster (http://www.bikiniatoll.com/divemaster%20advice.html)

I have 3 dive computers - a DR NiTek3, a TUSA IQ-700 (both on the Bikini Approved list), and a TUSA IQ-800 I picked up for just 'recreational' single mix Nitrox diving (which I got for $199 brand new with manufacturers' warranty) with a very much less annoying vibrating alarm and display size that is extra friendly to my ever-aging eyes.

When I was first diving, even when I used the PADI Wheel to try to figure out my likely repetitive group after a computer profile dive there never really was a good way to come up with a reasonably close estimate, and that was with my first dive computer, an Oceanic Data Plus, which used DSAT / Haldanean algorithms (matched the PADI tables for square profile dives - seen in the 'dive plan' mode).

Redundant dive computers with similar algorithms like I have can be a savvy option if you shop around.

If I'm Tech Diving which of course has a profile pre-set, I take my IQ-700 as primary and NiTek3 along as secondary backup, especially if something was to happen during the dive. When doing recreational diving, I take my IQ-800 as primary with my DR NiTek3 as backup. In either case, considering the investment made for my dive trips, this is cheap redundancy.

It doesn't boil down to the cost of square profile dive tables IMO, it comes down to the value of square profile dive tables, which is solely in the judgement of the individual.

I can tell you that once I was OW certified, I never executed a square profile dive after that - always computer profiles.

emclean
04-12-2010, 12:11
i know my LDS os still teaching the tables with PADI, but then again, we were also tought buddy breathing.

scubadiver888
04-12-2010, 15:15
I have been seeing this or something like this advertised .

"Get open water certified. Package includes dive computers, so no need to worry about dive tables!"

If you are new to diving, I would advise you to steer away from this type of attitude.

Just me two bits.

What is wrong with using a dive computer instead of tables? I would guess that MOST people diving today use a computer and hardly ever go back to using tables.

I think learning to dive without learning the difference between decompression and non-decompression diving, NDLs, etc. is a bad idea. You need to understand WHY the computer tells you what it does just as you need to understand WHY the dive tables tell you what it does.

So if you still learn all the theory and then rely on a computer to do the calculations it would be fine in my opinion. You should also take into consideration the sort of person who would take a course advertised like this. I would not take a course advertised like this. The sort of person who goes for something like this is going to go scuba diving on vacation and only if it is convenient.

The amount of information you require someone to know really depends on the type of person they are. If everyone has to know what I know to be able to dive, a LOT of people would not be allowed to dive and even more just wouldn't be interested in diving. Additionally, there are people who know WAY more than me. Does that mean I should quit diving? I don't think so.

Case in point:

- How much time does a 60 minute tissue compartment require to fill or empty completely?
- How many different compartments are their in the RDP?
- What is the m-value for each compartment?
- Which tissue compartment does the RDP use to control its "Surface Interval Credit Table?"

If you don't know the answer to these, you really don't understand the RDP tables. Should you stop diving? I would guess a LOT of people would say they don't need to know this to dive safely. And that is what it is all about. Is it safe to dive with a computer *AND* the proper training? A lot of people would say yes.

navyhmc
04-12-2010, 15:51
Okay, I will admit that old school was new shool when I started. Why should you learn the tables? Pure and simple: Back up plan! What do you do when you're in day 2 of a 7 day charter and your computer goes south on you? What if you don't have a spare? Are you done diving? Since I'm not a fan of trust me dives, I won't go off your computer. That leaves me hoping there's a spare computer on board the boat in the middle of a beautiful section of ocean and if I don't know tables and there's no spare computer then I'm now a deck hand/surface support person that paid big $$$ to be there. Can't safely dive and plan dives if you don't know the material. If you know the tables, it's still dive on! And more importantly, it's dive on safely. We won't go into borrowing a computer that you're not familiar with...

Bottom line, I use a computer now, finally after 30 plus years ofbeing a table only diver. Yes, they do help to safely extend bottom times, they do add a margin of safety to the dive, but not learning tables and the theory behind them leaves a big hole in the safety net.

As you say 888, it's knowing that makes it safer.

plot
04-12-2010, 16:41
i was a boyscout, if i'm stuck on a boat for 7 days, i'm having backup everything.

Rorschach
04-12-2010, 17:20
I concur, and I don't even have to be on a boat! If I'm paying for flights, accomodations, and diving, redundancy in dive computers is an inexpensive hedge in my experience. I will usually have 2 different wings with me on a trip as well.

I still take the PADI Wheel with me when traveling / diving because it's easily portable, and I never had any real difficulty understanding the priciples of physics and physiology involved.

I'd like to hear directly from someone with first-hand experience of such events who actually did figure out what repetive nitrogen group they were in via square profile tables, or the Wheel, after several days of a multi-day dive trip. I could use the tips, as I can't make it make sense even on the Wheel - unless you just want to say "after 6 hours even if my dive computer fails I'm OK to dive any given recreational profile because that's the maximum SI on the PADI tables"

My individual sense never could persuade me that was a viable position to take.

scubadiver888
04-12-2010, 21:45
Okay, I will admit that old school was new shool when I started. Why should you learn the tables? Pure and simple: Back up plan! What do you do when you're in day 2 of a 7 day charter and your computer goes south on you? What if you don't have a spare? Are you done diving? Since I'm not a fan of trust me dives, I won't go off your computer. That leaves me hoping there's a spare computer on board the boat in the middle of a beautiful section of ocean and if I don't know tables and there's no spare computer then I'm now a deck hand/surface support person that paid big $$$ to be there. Can't safely dive and plan dives if you don't know the material. If you know the tables, it's still dive on! And more importantly, it's dive on safely. We won't go into borrowing a computer that you're not familiar with...

Bottom line, I use a computer now, finally after 30 plus years ofbeing a table only diver. Yes, they do help to safely extend bottom times, they do add a margin of safety to the dive, but not learning tables and the theory behind them leaves a big hole in the safety net.

As you say 888, it's knowing that makes it safer.

I know people who would skip diving rather than learn tables. That is not you, that is not anyone who is on this board. These are the sort of people who don't know what a scuba charter is. They go to somewhere like Jamaica or Dominican Republic for vacation. While they are there they might get in one or two dives. PADI is trying to capture this market. Most these people will never need tables. They will dive 60' for 30 minutes then 40' for 40 minutes. Even with a zero surface interval this is fine.

EVERYONE I know who feels about scuba diving like I do (or more) learns tables. My shop teaches tables; if you don't like it go somewhere else. If you go to get your Nitrox, you re-learn tables. I can only think of one shop within a 100 miles that will teach OW without tables. He will still teach the theory behind the tables... then he'll try to set you up for the Computer Diving Specialty course ($125 plus you have to buy his computer :) ).

I really believe, people who need to learn tables will probably go beyond learning tables. People who don't need to learn tables will buy a computer but still understand the theory behind the computer. If a shop does not teach the theory behind the algorithm then they are bad instructors. PADI expects you to teach the students the theory just not using tables.

scubadiver888
04-12-2010, 21:57
I concur, and I don't even have to be on a boat! If I'm paying for flights, accomodations, and diving, redundancy in dive computers is an inexpensive hedge in my experience. I will usually have 2 different wings with me on a trip as well.

I still take the PADI Wheel with me when traveling / diving because it's easily portable, and I never had any real difficulty understanding the priciples of physics and physiology involved.

I'd like to hear directly from someone with first-hand experience of such events who actually did figure out what repetive nitrogen group they were in via square profile tables, or the Wheel, after several days of a multi-day dive trip. I could use the tips, as I can't make it make sense even on the Wheel - unless you just want to say "after 6 hours even if my dive computer fails I'm OK to dive any given recreational profile because that's the maximum SI on the PADI tables"

My individual sense never could persuade me that was a viable position to take.

If you look at the RDP, the section on Emergency Decompression states that you need to do an 8 minute deco stop if you exceed an NDL for no more than 5 minutes then stay out of the water for 6 hours. If you exceed the NDL for more than 5 minutes, you need to do a deco stop for 15 minutes or more (depending on air supply) then stay out of the water for 24 hours.

If my computer failed during the dive it is difficult, if not impossible, to know if I've exceeded the NDL and by how much. So I would assume worst case scenario, do a 15 minute or more deco stop then stay out of the water for 24 hours. By the way, I always carry a dive watch with me so I can time the deco stop should my computer fail.

If my computer failed between dives and I am sure it was working okay on the last dive, I feel comfortable knowing I didn't exceed any NDL. After each dive I'll write my computer info into a log book. If the last dive done with tables puts me off the pressure groups (i.e. beyond Z) then I'll assume worst case scenario and stay out for 6 hours.

navyhmc
04-13-2010, 11:23
While it's not scientific, I do something similar: I look at my 60' NDL for dive 2 at the 10 minute SI point. Since I know that the zero dives NDL on my Geo is 57 minutes I use that as a reference point to what my nitrogen loading is and what repetative group I would be in had my dive been a table dive and drop a letter group. (i.e. if after 10 minutes of SI, I have 20 minutes of NDL for dive 2, that would be a "P" diver at the end of the first dive. Drop one letter, I'm a "Q" diver.) But I do like a default "Z" too, built in safety.

I do understand that there are folks that would not dive if they absolutely had to learn tables, but in the back of my mind, it's not the safest way of doing business. Not saying it's not safe, just not as safe.

(maybe it falls back on the old saying: There are old divers, there are bold divers. But there are very few old and bold divers. ) :smiley20:

RedRattler
04-13-2010, 13:05
I was taught how to use the tables, and we did not even have computers in my classes. I am very thankful that I was "forced" to learn what the tables were, but I am also thankful that I have a computer to take with me going forward. The computer is a nice tool to have and use, but will not replace the knowledge I gained when learning how to use the tables. Also, not everyone can afford a computer when they 1st start off with scuba. I know I would not have one today if a co-worker did not give me his old one. It is hard to fins a justification of the added expence, after paying for the course and mandatory start up gear. If I was single and did not have to worry about eating for a week or 2, then the justificaiton may not be so hard :D

Noob
04-13-2010, 13:11
IMO, you should learn the tables. It is simple and always a great thing to have a back up if your computer fails or diving with someone who doesnt have a computer.

scubadiver888
04-13-2010, 13:21
IMO, you should learn the tables. It is simple and always a great thing to have a back up if your computer fails or diving with someone who doesnt have a computer.

Simple for one person is not simple for all people. Different people learn and work in different ways. If we teach the theory but not using tables, there are some people who would understand it better.

plot
04-13-2010, 15:35
IMO, you should learn the tables. It is simple and always a great thing to have a back up if your computer fails or diving with someone who doesnt have a computer.

It's also very forgettable and very easy for a new diver to screw up calculations on, making them think maybe they have 60 minutes of bottomtime at 100' when a more experienced diver knows that's waaaaaay off.

Classtime is better put to use teaching something more practicle, like the theory behind the tables instead of "Now follow this column... and take that number..."

Rorschach
04-13-2010, 17:13
I concur, and I don't even have to be on a boat! If I'm paying for flights, accomodations, and diving, redundancy in dive computers is an inexpensive hedge in my experience. I will usually have 2 different wings with me on a trip as well.

I still take the PADI Wheel with me when traveling / diving because it's easily portable, and I never had any real difficulty understanding the priciples of physics and physiology involved.

I'd like to hear directly from someone with first-hand experience of such events who actually did figure out what repetive nitrogen group they were in via square profile tables, or the Wheel, after several days of a multi-day dive trip. I could use the tips, as I can't make it make sense even on the Wheel - unless you just want to say "after 6 hours even if my dive computer fails I'm OK to dive any given recreational profile because that's the maximum SI on the PADI tables"

My individual sense never could persuade me that was a viable position to take.

If you look at the RDP, the section on Emergency Decompression states that you need to do an 8 minute deco stop if you exceed an NDL for no more than 5 minutes then stay out of the water for 6 hours. If you exceed the NDL for more than 5 minutes, you need to do a deco stop for 15 minutes or more (depending on air supply) then stay out of the water for 24 hours.

If my computer failed during the dive it is difficult, if not impossible, to know if I've exceeded the NDL and by how much. So I would assume worst case scenario, do a 15 minute or more deco stop then stay out of the water for 24 hours. By the way, I always carry a dive watch with me so I can time the deco stop should my computer fail.

If my computer failed between dives and I am sure it was working okay on the last dive, I feel comfortable knowing I didn't exceed any NDL. After each dive I'll write my computer info into a log book. If the last dive done with tables puts me off the pressure groups (i.e. beyond Z) then I'll assume worst case scenario and stay out for 6 hours.

I concur you have a reasonable, well-thought out approach that is not in line with the PADI OW training I took.

Have you ever actually done this during a dive trip - just curious?

My first response which was to Foo2's post - that somehow, having tables along mitigates having to wait 24 hours to go back in the water if you use a single computer and that computer fails.

For that to be true, you would need to plan and execute every single dive using tables (or The Wheel) adhering to the table (or Wheel) profiles on all dives instead of using a dive computer for any of the dives, considering the things that aren't spelled out on the tables but are spelled out in the training materials, as you've noted and I've been aware of. Last I saw was if you messed up and went into mandatory deco (and completed the deco) or lost your dive compter, it's 24 hours out of the water period when I took my PADI O/W 11 years ago.

fisheater
04-13-2010, 17:42
I know people who would skip diving rather than learn tables. That is not you, that is not anyone who is on this board. These are the sort of people who don't know what a scuba charter is. They go to somewhere like Jamaica or Dominican Republic for vacation. While they are there they might get in one or two dives. PADI is trying to capture this market. Most these people will never need tables. They will dive 60' for 30 minutes then 40' for 40 minutes. Even with a zero surface interval this is fine

That's probably the reasoning behind this. If so, isn't time that PADI renamed the current OW course "Supervised Open Water Diver?"

That appears to be the goal, so PADI (and the other rec agencies) should admit it. Then, folks with shortcut, benign conditions training won't get themselves in trouble by attempting dives beyond their training.

More traditional training could be term something like "Independent Open Water Diver" and include more dive planning, adverse
conditions and buddy/team awareness. Divers who only wish to get a few DM-led dives in during their annual tropical vacation need to be bothered with stuff they don't need to know and skills they'll never use.

in_cavediver
04-13-2010, 20:18
I concur, and I don't even have to be on a boat! If I'm paying for flights, accomodations, and diving, redundancy in dive computers is an inexpensive hedge in my experience. I will usually have 2 different wings with me on a trip as well.

I still take the PADI Wheel with me when traveling / diving because it's easily portable, and I never had any real difficulty understanding the priciples of physics and physiology involved.

I'd like to hear directly from someone with first-hand experience of such events who actually did figure out what repetive nitrogen group they were in via square profile tables, or the Wheel, after several days of a multi-day dive trip. I could use the tips, as I can't make it make sense even on the Wheel - unless you just want to say "after 6 hours even if my dive computer fails I'm OK to dive any given recreational profile because that's the maximum SI on the PADI tables"

My individual sense never could persuade me that was a viable position to take.

If you look at the RDP, the section on Emergency Decompression states that you need to do an 8 minute deco stop if you exceed an NDL for no more than 5 minutes then stay out of the water for 6 hours. If you exceed the NDL for more than 5 minutes, you need to do a deco stop for 15 minutes or more (depending on air supply) then stay out of the water for 24 hours.

If my computer failed during the dive it is difficult, if not impossible, to know if I've exceeded the NDL and by how much. So I would assume worst case scenario, do a 15 minute or more deco stop then stay out of the water for 24 hours. By the way, I always carry a dive watch with me so I can time the deco stop should my computer fail.

If my computer failed between dives and I am sure it was working okay on the last dive, I feel comfortable knowing I didn't exceed any NDL. After each dive I'll write my computer info into a log book. If the last dive done with tables puts me off the pressure groups (i.e. beyond Z) then I'll assume worst case scenario and stay out for 6 hours.

I concur you have a reasonable, well-thought out approach that is not in line with the PADI OW training I took.

Have you ever actually done this during a dive trip - just curious?

My first response which was to Foo2's post - that somehow, having tables along mitigates having to wait 24 hours to go back in the water if you use a single computer and that computer fails.

For that to be true, you would need to plan and execute every single dive using tables (or The Wheel) adhering to the table (or Wheel) profiles on all dives instead of using a dive computer for any of the dives, considering the things that aren't spelled out on the tables but are spelled out in the training materials, as you've noted and I've been aware of. Last I saw was if you messed up and went into mandatory deco (and completed the deco) or lost your dive compter, it's 24 hours out of the water period when I took my PADI O/W 11 years ago.

There was a pretty good discussion about this a while back. In that area - the consensus was an educated diver, who is pretty comfortable knowing what their prior profiles are and the model used in their computer, can make a jump to tables conservatively and safely. Its a calculated risk but still quite doable.

Rorschach
04-14-2010, 00:04
But this is contraindicated in the materials prsented in OW training - which after all is what the original post was about. If you follow the training materials as taught having a set of tables or The Wheel doesn't somehow instantly grant you leave to return to diving in less than 24 hours after your dive computer quit working.

However, the OP did not include details for what that specific class teaches one to do in the event of dive computer failure - it would be interesting to learn that answer.

Being a vacation only diver myself, my money would be that someone who has a single dive computer experiencing a computer failure during a dive trip and waiting 24 hours until the next dive (say it was something as simple as a battery failure with a spare battery readily available in luggage before departure) would still get more dive time in the water than a person solely using square profile tables or The Wheel at any typical tropical dive site appropriate for OW divers to dive at for the whole trip. Even if the computer failure wasn't simple to fix, someone who started the trip using a dive computer, having a computer failure, waiting 24 hours, then using square profile tables or The Wheel afterwards would likely still log more u/w time racked up vs. someone using only square profile tables or The Wheel for the entire duration of the dive trip.

Anyone who's interested in the local diving in Southeast Louisiana can send me a PM, but I recommend you watch the Louisiana specific episodes of "Dirty Jobs" first, as just a teaser for what awaits you here for diving opportunities.

There was an article in Undercurrent several years ago that showed the highest rates of DCI / dive were from divers executing square profile dives - they beat out Cozumel dive guides, liveaboard dive tourists, etc. that were using dive computers in this study. The study did note the groups in the analysis that executed square profile dives and got bent more tended to be diving in low vis, cold water relative to the other groups, and a few other factors that could be ranked as additional stressors. But, it still stands as a study showing square profile divers got more incidents of DCS than someone who might be doing 3 to 5 dives a day 6 days a week plus playing tank toter on & off the boats etc. in Cozumel - and the Cozumel dive guides had the next highest rate of DCS incidents.

I have no desire to dive the wrecks of Scapa Floe, nor do I aspire to be a Cozumel dive guide, even before seeing that report, but especially after seeing that report.

in_cavediver
04-14-2010, 04:45
As for what 'is taught' about computer failures - My OW class (many years ago) stated to 'Follow the manufacturer's directions'.

The question of what to do really comes down to what you know. If you know nothing, then 24hrs is a safe bet (for NDL diving). If you know a bit more about your computer/model - then 6 hours may be a safe bet. If you know even more - less.

For instance. When I started, I got a genesis DC. It was based on and implemenented the DSAT PADI model. As such, if it failed and I knew I was within NDL with it, I could assume I was a 'Z' diver on the PADI tables safely. A couple hours out of the water and I was back diving.

Still - I bet every class teaches to 'follow manufacturer guidelines' for computer failures.

Rorschach
04-14-2010, 12:44
You'd think the manufacturer's guidelines would recommend buying two of their same brand and model then, both boosting sales and providing redundancy!

Maybe I'll dabble in the dive computer market when I retire. I'd like to write that in a product's recommendations. Perhaps I can be a telecommuter for Scott Zeagle and come up with a Scubatoys-only model dive computer that recommends you buy and maintain 2 of them.

The 24 hours Foo2 referred to *I think* comes from the same spot I'd remembered seeing it. At least that's my interpretation of how 'done diving for the day' came across.

scubadiver888
04-18-2010, 07:37
If you look at the RDP, the section on Emergency Decompression states that you need to do an 8 minute deco stop if you exceed an NDL for no more than 5 minutes then stay out of the water for 6 hours. If you exceed the NDL for more than 5 minutes, you need to do a deco stop for 15 minutes or more (depending on air supply) then stay out of the water for 24 hours.

If my computer failed during the dive it is difficult, if not impossible, to know if I've exceeded the NDL and by how much. So I would assume worst case scenario, do a 15 minute or more deco stop then stay out of the water for 24 hours. By the way, I always carry a dive watch with me so I can time the deco stop should my computer fail.

If my computer failed between dives and I am sure it was working okay on the last dive, I feel comfortable knowing I didn't exceed any NDL. After each dive I'll write my computer info into a log book. If the last dive done with tables puts me off the pressure groups (i.e. beyond Z) then I'll assume worst case scenario and stay out for 6 hours.

I concur you have a reasonable, well-thought out approach that is not in line with the PADI OW training I took.

Have you ever actually done this during a dive trip - just curious?

My first response which was to Foo2's post - that somehow, having tables along mitigates having to wait 24 hours to go back in the water if you use a single computer and that computer fails.

For that to be true, you would need to plan and execute every single dive using tables (or The Wheel) adhering to the table (or Wheel) profiles on all dives instead of using a dive computer for any of the dives, considering the things that aren't spelled out on the tables but are spelled out in the training materials, as you've noted and I've been aware of. Last I saw was if you messed up and went into mandatory deco (and completed the deco) or lost your dive compter, it's 24 hours out of the water period when I took my PADI O/W 11 years ago.


I have not had a dive computer failure yet. I do transfer my dive from my computer to my logbook immediately after each dive. I also like to take that time to note the more important things, the name of the guide, the location, what I saw, what I liked, what I didn't like, my dive buddy's name, cool people I met on the boat, etc. :smiley2:

If my dive computer fails there is a good chance I will end up spending 24 hours out of the water.

cyclone3565
04-18-2010, 07:46
Just because we all learned tables and wheels, I am not sure I disagree. When is the last time we used them, or even saw them in our stuff.

Another way to look at it, how many here know how to drive a stick shift, used to be the norm, not anymore. As a society advances, technology advances it might be time to get away.

In ten, maybe even five years, will we still by books, wear a watch, or just read on a computer and use our cell for the time.

Tables have their place, but this is 2010.

scubadiver888
04-18-2010, 07:54
I know people who would skip diving rather than learn tables. That is not you, that is not anyone who is on this board. These are the sort of people who don't know what a scuba charter is. They go to somewhere like Jamaica or Dominican Republic for vacation. While they are there they might get in one or two dives. PADI is trying to capture this market. Most these people will never need tables. They will dive 60' for 30 minutes then 40' for 40 minutes. Even with a zero surface interval this is fine

That's probably the reasoning behind this. If so, isn't time that PADI renamed the current OW course "Supervised Open Water Diver?"

That appears to be the goal, so PADI (and the other rec agencies) should admit it. Then, folks with shortcut, benign conditions training won't get themselves in trouble by attempting dives beyond their training.

More traditional training could be term something like "Independent Open Water Diver" and include more dive planning, adverse
conditions and buddy/team awareness. Divers who only wish to get a few DM-led dives in during their annual tropical vacation need to be bothered with stuff they don't need to know and skills they'll never use.

I'm sure at some point PADI will come up with something like this. They just need to figure out how to market it and what kind of pricing everything will be. :smiley36:

Reading their training material it is easy to see that they are training very conservatively. People who ignore rules will get themselves into trouble regardless of what they are trained. Some people are just that way. Most people who will take a PADI course will follow the rules blindly. I would like to think that only with further knowledge will it occur to them that they are not going to die if they do something else.

Basically, a typical PADI OW is taught they will die if they don't follow the rules. The vagueness of things like DCS troubles them. The number of people I've met who worry they may have been bent is quite remarkable. My favourite is out of shape people lugging 100 lbs of gear (tanks, BCD, weights, etc.) to and from the pool. The next day they are sore and tired because they are out of shape but they start wondering if they are bent. They are usually happy to find out they cannot get bent in a 10' deep pool.

For whatever reason, PADI liked to call a diver who really should be with a guide in benign dive conditions an OW and people who really know what they are doing an AOW. I would guess, and this is totally a guess, people like to get their OW so they can tell people they are a scuba diver. If their card said "Supervised" it would not be as impressive.

Changing the name of the card isn't really going to change the way people dive. It might actually make the divers who will never be good at tables or diving in adverse conditions try to get to that level just so they can have the "Independent" diver card.

Rorschach
04-18-2010, 16:34
Just because we all learned tables and wheels, I am not sure I disagree. When is the last time we used them, or even saw them in our stuff.

Another way to look at it, how many here know how to drive a stick shift, used to be the norm, not anymore. As a society advances, technology advances it might be time to get away.

In ten, maybe even five years, will we still by books, wear a watch, or just read on a computer and use our cell for the time.

Tables have their place, but this is 2010.

My paradigm is changing from manual transmission as the norm to automatic transmission as the norm was not a progression in technology - there's still better power transfer and of course driver control of when the gears shift. It was simply a baseline shift. When I travel to Europe and tell folks there that many people in the USA have never driven a vehicle with manual transmission they think I'm joking at first.

Kik's Cars on Curacao told me they won't rent any of their manual transmission vehicles to anyone from the USA, but apologized when i told him I'd been driving manual transmission vehicles since 1975.

The only real 'technological advantage' I see for automatic transmission is when it's paired with technology that switches off certain cylinders in the engine when cruising (Dodge Charger 'semi-hemi' ads for example).

Flatliner
04-18-2010, 17:27
That's a tough one. I remember during Calculus in college the professor would spend 1/2 hour explaining how to do something and us working hard on it. When we finally got it, he would say, "ok, here's the short way to do that". Why not just teach the short method and show one example of how that theorem is proven.

It's a little different with the tables. Not every piece of gear has computers. What happens when one of these people go on a vacation and dive with rental gear. I doubt the rental gear has computers.

I still see this as a valuable skill to know.

I have a slightly different take than you with the same ultimate conclusion. My daughter is currently in her cert class. I don't see her ever diving with anything but a computer. However, I am still making sure she totally understands tables because I think that is the only way a diver will ever understand what is happening to the body when doing multiple dives per day. It is REALLY tough to grasp the concept of residual nitrogen loading for someone who doesn't understand dive computers. As a result, it is difficult to make an intelligent informed decision in a lot of dive situations without that basic understanding as well.

Flatliner
04-18-2010, 17:34
I know people who would skip diving rather than learn tables. That is not you, that is not anyone who is on this board. These are the sort of people who don't know what a scuba charter is. They go to somewhere like Jamaica or Dominican Republic for vacation. While they are there they might get in one or two dives. PADI is trying to capture this market. Most these people will never need tables. They will dive 60' for 30 minutes then 40' for 40 minutes. Even with a zero surface interval this is fine

That's probably the reasoning behind this. If so, isn't time that PADI renamed the current OW course "Supervised Open Water Diver?"

That appears to be the goal, so PADI (and the other rec agencies) should admit it. Then, folks with shortcut, benign conditions training won't get themselves in trouble by attempting dives beyond their training.

More traditional training could be term something like "Independent Open Water Diver" and include more dive planning, adverse
conditions and buddy/team awareness. Divers who only wish to get a few DM-led dives in during their annual tropical vacation need to be bothered with stuff they don't need to know and skills they'll never use.

I'm sure at some point PADI will come up with something like this. They just need to figure out how to market it and what kind of pricing everything will be. :smiley36:

Reading their training material it is easy to see that they are training very conservatively. People who ignore rules will get themselves into trouble regardless of what they are trained. Some people are just that way. Most people who will take a PADI course will follow the rules blindly. I would like to think that only with further knowledge will it occur to them that they are not going to die if they do something else.

Basically, a typical PADI OW is taught they will die if they don't follow the rules. The vagueness of things like DCS troubles them. The number of people I've met who worry they may have been bent is quite remarkable. My favourite is out of shape people lugging 100 lbs of gear (tanks, BCD, weights, etc.) to and from the pool. The next day they are sore and tired because they are out of shape but they start wondering if they are bent. They are usually happy to find out they cannot get bent in a 10' deep pool.

For whatever reason, PADI liked to call a diver who really should be with a guide in benign dive conditions an OW and people who really know what they are doing an AOW. I would guess, and this is totally a guess, people like to get their OW so they can tell people they are a scuba diver. If their card said "Supervised" it would not be as impressive.

Changing the name of the card isn't really going to change the way people dive. It might actually make the divers who will never be good at tables or diving in adverse conditions try to get to that level just so they can have the "Independent" diver card.

My cert is SSI and I would have to say that this isn't necessarly a PADI thing. I know it gets old to say "It's all about the instructor" but I really think it is.

My OW class was a total waste of time. The diving was great but the classroom was nothing more than an amway meeting for overpriced dive gear.

One of the best shops in my area is PADI and that is where I signed up for DM as well as where I signed my daughter up for OW.

brojack17
04-18-2010, 18:01
One of the two PADI sites and the SSI site here in Tulsa still teach tables. I just haven't talked to the other PADI site, but I bet he still teaches tables.

The SSI instructor said the tables section is in the appendix, but he refuses to not teach it. He said he would love to sell everyone a computer, but they still need to know why the computer is telling them what it is.

Quero
04-18-2010, 18:35
For now I'm teaching both tables and computer. My current student (doing Open Water Dives 1 & 2 today) went through the table stuff yesterday. Most instructors will be willing to teach tables if you just ask for it.

Rorschach
04-19-2010, 11:31
Plus, not all dive computers are the same.

The Cochran multi-mix dive computers that switch gas mixes according to pre-set progam input above water are the equivalent of vehicles with automatic transmissions.

Me personally I'll always stick with a multi mix computer that doesn't switch the mix until i tell it to via pressing buttons underwater during the dive. I control if / when gas switching occurs with the flexibility of 'lost gas' scenarios because I won't switch to a gas I've lost.

I absolutely agree there needs to be understanding what the computer is telling you and why it's displaying the information given at any point in the dive, but I would request consideration of any perception that teaching square profile divetables is the one way to achieve that objective (or even teaching The Wheel). I think there's an intermediate step for clarity.

The only direct comparison with square profile tables on the dive computers I own are when they are in the 'dive plan' mode to show maximum available bottom time at a given depth via a square profile.

Teaching math concepts like Euler Integration in conjunction with the square profile for showing how the dive computers are sampling the profile throughout the dive I think would enhance dive computer function understanding by students far more than by teaching The Wheel. It's not hard to show an overlay of a computer dive profile say at a shore dive sloping reef over a square dive profile to the same bottom depth and 'slice' it into thinner and thinner vertical slices with the X-axis being time and the y-axis being depth. You don't even have to mention words like Euler Integration to spook anyone, just a simple set of slide presentations; with PowerPoint, you could even animate the slides.

jj1987
04-19-2010, 15:23
- How much time does a 60 minute tissue compartment require to fill or empty completely?
- How many different compartments are their in the RDP?
- What is the m-value for each compartment?
- Which tissue compartment does the RDP use to control its "Surface Interval Credit Table?"


A 60min tissue doesn't exist on the ZHL16 based algo's many computers use. Besides, recreational divers aren't even close to the compartment that's often mistakenly referred to as the 60min compartment.

I don't think the RDP has tissue compartments? Isn't that based off of navy tables that were published long before 1983 when Buhlmann published his first paper?

M values are pulled from a table, memorizing them would be useless. Not to mention that you'd have to convert them to bar for them to work with the formula, and that's not math you can do in your head. Each tissue has an M value, as well as an A/B value for both n2 and he that's used to calculate the offgassing. You'd have to memorize 48 numbers, all with very high precision. Even with a calculator underwater you couldn't use them nor would you want to.

Not sure what tissue compartment is used. I thought all were, to be honest. Before going up a level, you compare the tissue pressure at the "new" depth to the tissues m value, and hold until you're "clear". If you're not clear, you repeat the a-b values for an additional clock interval and then check again.


If you don't know the answer to these, you really don't understand the RDP tables. Should you stop diving? I would guess a LOT of people would say they don't need to know this to dive safely. And that is what it is all about. Is it safe to dive with a computer *AND* the proper training? A lot of people would say yes.
Sounds to me like you have some misunderstandings as well. It's good to know buzz words, but I don't think every diver needs to know how to calculate this stuff by hand. I would stick to valid reasons to not dive a computer such as mismatched algorithms (can't match your buddy), the fact that they dont match tables (you can't dive a computer and just switch to tables if it fails), unnecessary cost (I've done 3+ hours dives in the 100ft range without one), inability to keep up with modern deco theory and/or modify deco to match your own body's feedback, etc.

scubadiver888
04-19-2010, 19:00
- How much time does a 60 minute tissue compartment require to fill or empty completely?
- How many different compartments are their in the RDP?
- What is the m-value for each compartment?
- Which tissue compartment does the RDP use to control its "Surface Interval Credit Table?"


A 60min tissue doesn't exist on the ZHL16 based algo's many computers use. Besides, recreational divers aren't even close to the compartment that's often mistakenly referred to as the 60min compartment.

I don't think the RDP has tissue compartments? Isn't that based off of navy tables that were published long before 1983 when Buhlmann published his first paper?

M values are pulled from a table, memorizing them would be useless. Not to mention that you'd have to convert them to bar for them to work with the formula, and that's not math you can do in your head. Each tissue has an M value, as well as an A/B value for both n2 and he that's used to calculate the offgassing. You'd have to memorize 48 numbers, all with very high precision. Even with a calculator underwater you couldn't use them nor would you want to.

Not sure what tissue compartment is used. I thought all were, to be honest. Before going up a level, you compare the tissue pressure at the "new" depth to the tissues m value, and hold until you're "clear". If you're not clear, you repeat the a-b values for an additional clock interval and then check again.


If you don't know the answer to these, you really don't understand the RDP tables. Should you stop diving? I would guess a LOT of people would say they don't need to know this to dive safely. And that is what it is all about. Is it safe to dive with a computer *AND* the proper training? A lot of people would say yes.
Sounds to me like you have some misunderstandings as well. It's good to know buzz words, but I don't think every diver needs to know how to calculate this stuff by hand. I would stick to valid reasons to not dive a computer such as mismatched algorithms (can't match your buddy), the fact that they dont match tables (you can't dive a computer and just switch to tables if it fails), unnecessary cost (I've done 3+ hours dives in the 100ft range without one), inability to keep up with modern deco theory and/or modify deco to match your own body's feedback, etc.

I think you are looking at the questions in the context of decompression diving. Everything about the RDP is based on no decompression diving.

Regardless, the entire point of my post was that you don't need to know this information to be a recreational diver.

Flatliner
04-20-2010, 05:01
My point was that the concept of residual nitrogen isn't really understood by someone who only knows computers. It didn't take a math discussion for my daughter to grasp that the computer gives her credit for all the time spent at shallower depths and that with the table you have to assume all the time was spent at the deeper depths.

scubastud
04-21-2010, 05:57
I am going to stick with my original position. If you do not understand dive tables, can't read them and can' plan a dive- you have no business in the water without supervision and should not be allowed an "Open Water" certification.

ashcoal
04-21-2010, 07:58
My 2 cents on the issue is that instructors really need to be teaching both the dive tables and computer. I think the dive tables are necessary because not everyone will buy a or have a computer. That seems like cheap insurance. I also think that teaching the computer is necessary or the student is getting short changed. This is all regardless of which algorithm a computer uses, how many tissue compartments are monitored, etc.

I went through PADI's OW course a few months ago. It was all about the tables and their eRDP. Great, I know how to work the dive table and its not hard at all and I'm glad that I went through it. The problem is that now I have picked up a computer and the only way that I'm learning it is by reading the manual because I received NO instruction on computer use in the PADI materials or during my pool dives. I fully intend to know the computer forwards and backwards before I actually dive with, but it seems kind of silly not to have given some basic instruction on the use of dive computers since they are available with every rental. Granted there are a lot of computers on the market and I'm sure they all operate somewhat differently, but I'm sure they are all similar too.

It seems to me that teaching both the computer and the dive tables would be the prudent thing to do, if nothing else, from a liability standpoint.

mitsuguy
04-21-2010, 08:28
If a student is going through the dive computer option, it is a requirement that he/she have a dive computer. I believe it is actually acceptable if they are using a rented computer, however, our stance on it is that if you don't own a computer, you can't take the computer course.

With that in mind, we have not had a single student go through the computer version of the course. When I teach the course, I teach all 3. Typically, our students are using the table version of the course, though we also do the eRDP and the computer version if needed. No matter which course they are doing, I teach that course the most in depth, but I also touch on the other options available. After the end of each dive day, I show them what the different NDL's are, based on each different item: computer, RDP, eRDP... I fully believe that most recreational divers would be much safer with a dive computer, as without one, most recreational, vacation divers, follow along a dive guide and "trust" he is ok... Not the rule, but, I see it all the time...

And, Rorschach, what about adding the new DSG transmissions that are essentially a manual, but completely computer/mechanically controlled to the comparison??? :)

ashcoal
04-21-2010, 08:46
I did the PADI e-Learning course over the internet. There was not a computer option that I'm aware of. I was able to use the RDP tables or the eRDP (I did both). I thought they were supposed to contian the same information, but found out recently that the eRDP is supposed to be more exact. It sounds like PADI may offer a live computer OW class but not in e-Learning. Or is the computer option something that your shop offers outside or in addition to the PADI curriculum?

mitsuguy
04-21-2010, 09:25
I did the PADI e-Learning course over the internet. There was not a computer option that I'm aware of. I was able to use the RDP tables or the eRDP (I did both). I thought they were supposed to contian the same information, but found out recently that the eRDP is supposed to be more exact. It sounds like PADI may offer a live computer OW class but not in e-Learning. Or is the computer option something that your shop offers outside or in addition to the PADI curriculum?

The eRDP is similar to the old, now outdated Wheel. It allows multi level dive planning, and is in 5 ft increments, instead of the 10 ft increments that the standard RDP offers...

The computer option has not been implemented yet on the e-learning, but I imagine it will be soon, as PADI now has dive computer simulations for PC's... As for right now, you can only do the computer option live.

jj1987
04-21-2010, 10:10
I am going to stick with my original position. If you do not understand dive tables, can't read them and can' plan a dive- you have no business in the water without supervision and should not be allowed an "Open Water" certification.
What's the difference between following a computer blindly and following a set of tables blindly? I don't get it. Using square profile tables has to be the stupidest idea I've heard of for recreational diving as it severely limits repetitive dives. This isn't acceptable to me when I'm paying charter fees...I want my full dive time possible.

The first part of this classroom is EXCELLENT for open water divers. I highly recommend it, even if you tune out the actual decompression dive planning parts. You'll understand the theory behind the tables and computers better.
http://www.unifiedteamdiving.com/page/ratio-deco

Rorschach
04-21-2010, 16:41
... I fully believe that most recreational divers would be much safer with a dive computer, as without one, most recreational, vacation divers, follow along a dive guide and "trust" he is ok... Not the rule, but, I see it all the time...

And, Rorschach, what about adding the new DSG transmissions that are essentially a manual, but completely computer/mechanically controlled to the comparison??? :)

We're no fans of 'mob dives' either for numerous reasons including what you've listed and also see regularly.

I'll have to look at the DSG technology, I haven't examined that. My wife and I have a deal that next round of car buying she'll get the utility vehicle (she'd like something like a Murano) while I'd get the sports vehicle (with the re-release of the Challenger, this is all but a done deal). But, first things first for the moment, My truck has about 130,000 miles on it and still in decent shape, her Trans-Am has over 160,000 miles on it.

But I won't buy the 'semi-Hemi' - the Challenger MUSt come with a clutch pedal and stick - I'm not dropping that kind of coin without that.

OK, I looked at the transmission - I would still prefer to select upshift & downshift myself, and a skillful manual transmission driver can minimize the 'lurching' - problem is there aren't many of us around any more. I did have a business trip to Germany where i drove a diesel 6 speed manual Audi A3 all over the place on one weekend - no acceleration monster but good tight steering to 240 kph - but on a long straigtaway a black Porsche in front of me left me like I was standing still at 240 kph!

At Exective Charm School, they grouped a bunch of us who all scored as extremely averse to micro-management, and a colleague in that group from Scotland shouted out in a deep brougue

"Contrrrollll is Guuuuud!"

with a clenched fist. Summed us up pretty well.:smiley2:

edit - with reference to dive computers, I guess the best analogy of DSG technology would be rebreathers with gas sensors that adjust a mix for a given ppO2.

Rorschach
04-21-2010, 16:49
My 2 cents on the issue is that instructors really need to be teaching both the dive tables and computer. I think the dive tables are necessary because not everyone will buy a or have a computer. That seems like cheap insurance. I also think that teaching the computer is necessary or the student is getting short changed. This is all regardless of which algorithm a computer uses, how many tissue compartments are monitored, etc.

I went through PADI's OW course a few months ago. It was all about the tables and their eRDP. Great, I know how to work the dive table and its not hard at all and I'm glad that I went through it. The problem is that now I have picked up a computer and the only way that I'm learning it is by reading the manual because I received NO instruction on computer use in the PADI materials or during my pool dives. I fully intend to know the computer forwards and backwards before I actually dive with, but it seems kind of silly not to have given some basic instruction on the use of dive computers since they are available with every rental. Granted there are a lot of computers on the market and I'm sure they all operate somewhat differently, but I'm sure they are all similar too.

It seems to me that teaching both the computer and the dive tables would be the prudent thing to do, if nothing else, from a liability standpoint.

It introduces an additional level of mis-understanding as well because the people who write the dive computer manuals I seriously doubt are actual divers using the end product. I have not had a single dive computer I've owned with an intuitively obvious clear-cut manual (and I doubt I've ever owned a PC or many examples of PC software that don't have the same issue).

I think Mitsuguy has the right fundamental approach - teach all three, and perhaps the dive computer e-learning will have material like graphic slide overlays to aid in the understanding of what's different between all three methods.

Often people are overly optmisitic - in our ANDI advanced nitrox training manual from 1999 / 2000 Ed Betts predicted no 'air only' dive computers would be sold on the market within two years!

scubastud
04-21-2010, 17:06
I am going to stick with my original position. If you do not understand dive tables, can't read them and can' plan a dive- you have no business in the water without supervision and should not be allowed an "Open Water" certification.
What's the difference between following a computer blindly and following a set of tables blindly? I don't get it. Using square profile tables has to be the stupidest idea I've heard of for recreational diving as it severely limits repetitive dives. This isn't acceptable to me when I'm paying charter fees...I want my full dive time possible.

The first part of this classroom is EXCELLENT for open water divers. I highly recommend it, even if you tune out the actual decompression dive planning parts. You'll understand the theory behind the tables and computers better.
Ratio Deco - Unified Team Diving (http://www.unifiedteamdiving.com/page/ratio-deco)les


Where did I say "follow tables blindly"?
I said "UNDERSTAND tables, can't read them, and can't plan a dive".

If you are not taking the time to actually read my posts, I would ask you to kindly not respond to them.

:smiley31:

Rorschach
04-21-2010, 17:16
The vis would have to be almost nonexistant to follow anything blindly.

This is why I eschew the local diving here, but anyone who wants to demonstrate ratio deco while striving for a specialty underwater herpetologist using the Braille method of navigation here is welcome to try:smiley2:

I recommend you have a good medical plan if you do so - I don't know DAN's nor DiveAssure's position on water mocassin envenomation coverage nor gator wounds

plot
04-22-2010, 15:47
Quit trying to turn 30' guided once a year clear warm blue water vacation divers into tech divers... fact is, they don't need an excessive level of understanding of a table with a bunch of columns and it's probably safer that they don't know how to use the tables and try to plan a dive by them as it's just something they'll screw up when they are out on their own.

these are the same types of divers that won't mind spending money on a computer which will have their asses covered. it's an easy sell to a carribean diver. "complicated maths stuff you won't remember from year to year and you could end up dead, or this handy little thing you put on your wrist and it'll tell you exactly what to do..."

Quero
04-22-2010, 16:30
I did the PADI e-Learning course over the internet. There was not a computer option that I'm aware of. I was able to use the RDP tables or the eRDP (I did both). I thought they were supposed to contian the same information, but found out recently that the eRDP is supposed to be more exact. It sounds like PADI may offer a live computer OW class but not in e-Learning. Or is the computer option something that your shop offers outside or in addition to the PADI curriculum?

The eRDP is similar to the old, now outdated Wheel. It allows multi level dive planning, and is in 5 ft increments, instead of the 10 ft increments that the standard RDP offers...

The computer option has not been implemented yet on the e-learning, but I imagine it will be soon, as PADI now has dive computer simulations for PC's... As for right now, you can only do the computer option live.
Cody has given you the answer in terms of what is and isn't available online vs. live. But even in face-to-face teaching, the program isn't yet entirely smooth and integrated.

There's a new, not-required PADI book called How to Choose and Use a Dive Computer with Knowledge Reviews that replace those in Modules 4 and 5 of the "old" Open Water student manual. In order to teach only the computer version of the course, we need to ask students to buy two manuals and replace chapters 4 and 5 of the main book with the new book. Then we have to adapt the quizzes and final exam so that table questions don't count. The new quiz and final exam questions have been published only as errata at this point.

As far as what computer students learn to use in the computer version of the course, I have a stock of rental computers and I make a photocopy of the laminated "quick guide". I don't require students to own their own computers just as I don't require them to own any other gear. Once students know what one dive computer typically does, they should be able to make the switch to a different computer simply by consulting the user information that comes with every computer. (Given that we keep going back to comparisons between operating a car and diving, I'll say that switching computers is like getting behind the wheel of a rental car and figuring out where all the levers, buttons, and releases are in an unfamiliar vehicle--you KNOW what should be there, it's just a matter of familiarizing yourself.)

scubadiver888
04-22-2010, 16:52
I did the PADI e-Learning course over the internet. There was not a computer option that I'm aware of. I was able to use the RDP tables or the eRDP (I did both). I thought they were supposed to contian the same information, but found out recently that the eRDP is supposed to be more exact. It sounds like PADI may offer a live computer OW class but not in e-Learning. Or is the computer option something that your shop offers outside or in addition to the PADI curriculum?

The eRDP is similar to the old, now outdated Wheel. It allows multi level dive planning, and is in 5 ft increments, instead of the 10 ft increments that the standard RDP offers...

The computer option has not been implemented yet on the e-learning, but I imagine it will be soon, as PADI now has dive computer simulations for PC's... As for right now, you can only do the computer option live.
Cody has given you the answer in terms of what is and isn't available online vs. live. But even in face-to-face teaching, the program isn't yet entirely smooth and integrated.

There's a new, not-required PADI book called How to Choose and Use a Dive Computer with Knowledge Reviews that replace those in Modules 4 and 5 of the "old" Open Water student manual. In order to teach only the computer version of the course, we need to ask students to buy two manuals and replace chapters 4 and 5 of the main book with the new book. Then we have to adapt the quizzes and final exam so that table questions don't count. The new quiz and final exam questions have been published only as errata at this point.

As far as what computer students learn to use in the computer version of the course, I have a stock of rental computers and I make a photocopy of the laminated "quick guide". I don't require students to own their own computers just as I don't require them to own any other gear. Once students know what one dive computer typically does, they should be able to make the switch to a different computer simply by consulting the user information that comes with every computer. (Given that we keep going back to comparisons between operating a car and diving, I'll say that switching computers is like getting behind the wheel of a rental car and figuring out where all the levers, buttons, and releases are in an unfamiliar vehicle--you KNOW what should be there, it's just a matter of familiarizing yourself.)

And if you are still unsure about using a computer other than the one you did your OW training with, you can always sign up for the PADI Multilevel & Computer Dive Adventure dive. :smiley2:

navyhmc
04-22-2010, 19:38
I can see bot hsides of the "learn the tables" debate. I do agree that if all you do are a couple of resort dives each year in the Carib it's not as important as some one who is a push the limits type of diver-get 5-6 dives per day when possible. But I will say that for me, the square profile dive plan has never let me down and neither has the square profile multilevel dive-this includes planning them out before the wheel came into being. That strong understanding helped me greatly when I made the switch to a PDC.

As anyone who knows me is aware, I'm not big on trust me dives. I want to be able to handle the situation no matter what happens. Which is why I have a stonrg desire to know and work the tables. Those who are comfortable totally relying on their PDC and the planning of the DM, that is fine, as long as you are comfortable with that type of planning and diving.

Rorschach
04-22-2010, 22:29
We skip the DM and do our own planning (and diving) 90+% of the time these days.

Rorschach
04-22-2010, 22:35
Quit trying to turn 30' guided once a year clear warm blue water vacation divers into tech divers... fact is, they don't need an excessive level of understanding of a table with a bunch of columns and it's probably safer that they don't know how to use the tables and try to plan a dive by them as it's just something they'll screw up when they are out on their own.

these are the same types of divers that won't mind spending money on a computer which will have their asses covered. it's an easy sell to a carribean diver. "complicated maths stuff you won't remember from year to year and you could end up dead, or this handy little thing you put on your wrist and it'll tell you exactly what to do..."

We don't fit your paradigm - we're caribbean (and other tropical) vacation tech divers who use dive planning software for tech profiles with redundant computers as backup, and simply use redundant computers for 'recreational' dives.

We see value in dive computers, but we can do square profile tables and The Wheel as well (never messed with the eRDP and never plan to).

With the excellent safety record Bikini Atoll Divers had while they were in operation with profiles of 2 mandatory deco obligation dives per day, with redundant multi-mix dive computers as their most flexible contingency option, it puts a whole different perspective on "divers who will buy computers to have their asses covered" than you've presented.

We deal with far more complicated math stuff than dive tables every workday, and I was using SCBA for about a decade in IDLH environments before I added the "u". Scuba is simply partcipating in activities in another form of IDLH environment (unless you have gills). Just did my annual firefighter refresher training yesterday with outstanding results, quantitative respirrator fit test recertification is due for me next month.

plot
04-23-2010, 16:07
Quit trying to turn 30' guided once a year clear warm blue water vacation divers into tech divers... fact is, they don't need an excessive level of understanding of a table with a bunch of columns and it's probably safer that they don't know how to use the tables and try to plan a dive by them as it's just something they'll screw up when they are out on their own.

these are the same types of divers that won't mind spending money on a computer which will have their asses covered. it's an easy sell to a carribean diver. "complicated maths stuff you won't remember from year to year and you could end up dead, or this handy little thing you put on your wrist and it'll tell you exactly what to do..."

We don't fit your paradigm - we're caribbean (and other tropical) vacation tech divers who use dive planning software for tech profiles with redundant computers as backup, and simply use redundant computers for 'recreational' dives.

We see value in dive computers, but we can do square profile tables and The Wheel as well (never messed with the eRDP and never plan to).

With the excellent safety record Bikini Atoll Divers had while they were in operation with profiles of 2 mandatory deco obligation dives per day, with redundant multi-mix dive computers as their most flexible contingency option, it puts a whole different perspective on "divers who will buy computers to have their asses covered" than you've presented.

We deal with far more complicated math stuff than dive tables every workday, and I was using SCBA for about a decade in IDLH environments before I added the "u". Scuba is simply partcipating in activities in another form of IDLH environment (unless you have gills). Just did my annual firefighter refresher training yesterday with outstanding results, quantitative respirrator fit test recertification is due for me next month.

I wasn't talking about the people argueing in this thread specifically, I was talking about 98% of the scuba divers the dive industry churns out. They simply don't need to know how to use tables. The other 2% will learn when they work towards advancing their training to do more tech oriented dives.

jj1987
04-23-2010, 19:15
I am going to stick with my original position. If you do not understand dive tables, can't read them and can' plan a dive- you have no business in the water without supervision and should not be allowed an "Open Water" certification.
What's the difference between following a computer blindly and following a set of tables blindly? I don't get it. Using square profile tables has to be the stupidest idea I've heard of for recreational diving as it severely limits repetitive dives. This isn't acceptable to me when I'm paying charter fees...I want my full dive time possible.

The first part of this classroom is EXCELLENT for open water divers. I highly recommend it, even if you tune out the actual decompression dive planning parts. You'll understand the theory behind the tables and computers better.
Ratio Deco - Unified Team Diving (http://www.unifiedteamdiving.com/page/ratio-deco)les


Where did I say "follow tables blindly"?
I said "UNDERSTAND tables, can't read them, and can't plan a dive".

If you are not taking the time to actually read my posts, I would ask you to kindly not respond to them.

:smiley31:
I'm not real sure how you can understand tables. Correct me if I'm wrong, but there's no mathematical logic behind them other than observational studies is there? I was under the impression that there wasn't, but either way they don't represent anywhere close to modern deco theory so I still don't see them as a great thing to be teaching new divers.

in_cavediver
04-25-2010, 12:27
I am going to stick with my original position. If you do not understand dive tables, can't read them and can' plan a dive- you have no business in the water without supervision and should not be allowed an "Open Water" certification.
What's the difference between following a computer blindly and following a set of tables blindly? I don't get it. Using square profile tables has to be the stupidest idea I've heard of for recreational diving as it severely limits repetitive dives. This isn't acceptable to me when I'm paying charter fees...I want my full dive time possible.

The first part of this classroom is EXCELLENT for open water divers. I highly recommend it, even if you tune out the actual decompression dive planning parts. You'll understand the theory behind the tables and computers better.
Ratio Deco - Unified Team Diving (http://www.unifiedteamdiving.com/page/ratio-deco)les


Where did I say "follow tables blindly"?
I said "UNDERSTAND tables, can't read them, and can't plan a dive".

If you are not taking the time to actually read my posts, I would ask you to kindly not respond to them.

:smiley31:
I'm not real sure how you can understand tables. Correct me if I'm wrong, but there's no mathematical logic behind them other than observational studies is there? I was under the impression that there wasn't, but either way they don't represent anywhere close to modern deco theory so I still don't see them as a great thing to be teaching new divers.

Depends on the model. Many are math based and lend themselves toward tweaking. Some are based on bubble physics, some on diffusion gradients other on simple theoretical items. The verification portion of the models are all observational in nature though.

As for 'modern' vs 'traditional' vs whatever deco theory - its all in the eye of the beholder. Any deco model can be used to generate tables - even repetive tables. The key is finding a model that agrees with your specific body and building the personal 'history' with said model. I do not understand those who want to jump to the latest and greatest new model - assuming its a good models for thier body. Give me an advantage or a reason to change from what works - then I'll consider it - otherwise - why fix something that ain't broke.

Most rec divers never need to do this or know this. A generic model - of any vintage, with conservatism, is applied and covers 99% of divers. For those who are 'high risk' divers, they're training tells them to be even more conservative - which should keep them OK. A few cases of 'undeserved' hits occur each year but those numbers are low. Even deep stops, which are debated now, show little benefits for the NDL diver. (I think they are good idea for other related reasons - controlling the ascent speed/profile mainly)

Lastly - how I do interpret understanding tables. Simply put - I think most divers should have a basic understanding of the depth/time limits curve. I don't care if you dive tables or a computer - if you device says you can spend 40 minutes at 110' without deco - you should be able to recognize this as wrong. I have seen a computer spit out bad information (very low battery) and a diver should be able to recognize this. No background on the time limits means no frame of reference to know if the info provided is good or bad.

I know most rec divers can't tell you the limits for a given depth but I think they should be able to. I have a soapbox I could get on but I will spare many an not.

ontheheap
06-02-2010, 22:53
I have been seeing this or something like this advertised .

"Get open water certified. Package includes dive computers, so no need to worry about dive tables!"

If you are new to diving, I would advise you to steer away from this type of attitude.

Just me two bits.

That's odd. My class used computers but we still planned our dives and learned the tables.

Rorschach
06-08-2010, 18:36
The latest issue of Alert Diver has put together an article titled "Your dive computer fails - now what?"

The #1 recommendation is dive with two dive computers using the same or very similar algorithms.

oddly, the final answer if you have no other backup options available is sstated to wait 18 hours before diving again, instead of the 24 I expected to see. interesting.

The wife had a rental Hyundai Sonata on a recent business trip with a 6 speed DSD transmission and I think I've lost the battle for having a pedal for the left foot to make use of while driving - maybe whoever owns Chrysler will make this transmission an option in the future. *sigh*

Splitlip
06-08-2010, 18:45
My daughter was certed at a PADI facility about a year and a half ago. They did not "teach" computers until they let them dive them for the two required 60 footers and free 60 footer.

Still had to study, test and plan with tables.

Splitlip
06-08-2010, 18:56
I think it's pretty lame to not teach tables. What if your computer fails? Then you're done diving for the day whether you like it or not. Not to mention a computer isn't always the first thing that you run out and buy after you are certified. Tables are free!

All our safety training is to plan for the "what if" scenarios.

FTR, I have had 3 computer failures in the last 12 years. Always had a back up timer and depth gauge along with my tables. I completed a very sketchy deep wreck dive with a very rich mix using my Aqualand watch with tables I had in a pocket.

Although now I dive with 2 computers in addition to my Aqualand watch/gauge. I have 3 Uwatecs, 1 Aeris, 1 Oceanic and 1 Tusa. That is two each for me and my daughter with 2 backup backups. :smilie39: (In addition to my Aqualand! :smiley32:)

navyhmc
06-09-2010, 03:08
The latest issue of Alert Diver has put together an article titled "Your dive computer fails - now what?"

The #1 recommendation is dive with two dive computers using the same or very similar algorithms.

oddly, the final answer if you have no other backup options available is sstated to wait 18 hours before diving again, instead of the 24 I expected to see. interesting.

The wife had a rental Hyundai Sonata on a recent business trip with a 6 speed DSD transmission and I think I've lost the battle for having a pedal for the left foot to make use of while driving - maybe whoever owns Chrysler will make this transmission an option in the future. *sigh*

Actually, the 18 hours to me does make sense, when you consider that you're a "New Diver" for tables after a 12 hour SI. The question should be why 18 hours and not 12 hours?

Rorschach
06-09-2010, 14:57
only DAN knows . . . . I didn't see a rationale in the article where the 18 hour option is printed.

Can you explain your rationale -navyhmc? It's probably better than DAN's and undoubtably less narcane than DAN's.

I found DAN's latest article on PFO in this latest issue medieval in how far this isuue is handled considering all the time & technology chages since I first saw an article in the Spring 2001 issue of immersed magazine (and that's the only immersed magazine in my hardcopy archives) but I digress.

bigman241
06-09-2010, 17:35
TABLES TABLES AND MORE TABLES. We where taught on tables and had I not been I would have tossed a up roar. I have a 900 computer does that mean when I do a dive next week to say 50 feet I wont pick up my table. No I will and more so for practice then anything. If I am on a island diving and my computer fails I do not want to drop 900 bucks when on vacation nor do I want to sit on the beach. The computer is there to give me my air without a hose, my depth without a hose and my recommend dive time. I also like the fact it tells me how long I have been down, the time and how long I should stay down. Mine also tells me how long I have based on my air use. Which I like well I think that why the time keeps changing. Though all of them properly do this. Like some have said the more advance you go the more they want you to use the tables.

navyhmc
06-09-2010, 18:51
only DAN knows . . . . I didn't see a rationale in the article where the 18 hour option is printed.

Can you explain your rationale -navyhmc? It's probably better than DAN's and undoubtably less narcane than DAN's.

I found DAN's latest article on PFO in this latest issue medieval in how far this isuue is handled considering all the time & technology chages since I first saw an article in the Spring 2001 issue of immersed magazine (and that's the only immersed magazine in my hardcopy archives) but I digress.

Rorschach: My rationale comes straight from the PADI table rules. Surface intervals over 12 hours are considered new dives in regards to nitrogen levels.

When you figure your nitrogen levels and the half lives in even the slow tissues, the "rule of 7" for half lives comes into play. So I would imagine that after 12 hours from the last dive, 99% of the tissue loading from a dive(s) is back to normal.

The half life rule of "Rule of 7" stipulates that when you have had 7 half life time frames, that whatever is considered gone. i.e. if a drug has a 2 hour half life, that drug is considered totally out of your system in 14 hours.

Rorschach
06-10-2010, 16:24
Gotcha - been using redundant computers so long I missed the 12 hour rule myself. It's not uncommon for us to show 24+ hours time to desaturate several days on dive trips we take, even sticking within computer NDL limits for our Dive Rite & Tusa similar algorithm comps.

I'll guess the additional 6 hours are a DAN standard overdesign / safety factor / conservatism: for flying after diving it's > or = 18 hours for a singe NDL dive and > or = 24 hours for multiple dives NDL or not.

LeeParrish
06-11-2010, 22:31
Gotcha - been using redundant computers so long I missed the 12 hour rule myself. It's not uncommon for us to show 24+ hours time to desaturate several days on dive trips we take, even sticking within computer NDL limits for our Dive Rite & Tusa similar algorithm comps.

I'll guess the additional 6 hours are a DAN standard overdesign / safety factor / conservatism: for flying after diving it's > or = 18 hours for a singe NDL dive and > or = 24 hours for multiple dives NDL or not.

I thought the latest DAN recommendations were 12 hours for single dives, 18 for repetitive as long as you are within NDL either way. If you are a DAN member you can go read the proceedings from the last conference on this subject. It's actually pretty amusing reading the discussion at the end of the document which is a transcript of the doctors, scientists, and agency representatives discussing what they think the recommendation should be. They spent quite a bit of time deciding if the number should be 17 or 18 :smiley5:.

Rorschach
06-12-2010, 06:23
Looks like you're right. I missed this too using dive computers and redundant dive computers for as long as we have now.

DAN Divers Alert Network (http://www.diversalertnetwork.org/medical/faq/faq.aspx?faqid=54)

This may even further reinfoce 12 hours as the DAN standard 'fudge factor' since by the PADI tables only, you're a new diver after 6 hours per the tables. there is undoubtably a lot of number crunching that goes along with that.

However, it begs the question why DAN published a last option if you have no other means of approximating your RNT or repetitive dive group to be an 18 hour surface interval before resuming diving, and not anything to do with air travel associated with the "Your Dive Computer fails - Now What?"

Puzzling . . .

Everything else is laid out in 6 hour increments past that point, except it's extremely vauge on appropriate SI after dives with mandatory deco stop obligations.

For ourselves, we've always used the greater of 24 hours OR the time to desat as per the algorithm in our dive computers, which as I mentioned, can exceed 24 hours even on trips where all our dives were made within NDL computer limits.

LeeParrish
06-12-2010, 06:38
I studied the new recommendations pretty hard because last year when I was in Australia if I followed the old 24 hour recommendation after multi-day dives it meant I would lose the entire last day of diving in the morning. I was really happy when I saw the 18 hour guideline, since that let me dive until noon and still get a flight out early the the next morning. And an extra 3 dives on the GBR was well worth it to me. Then I did what they recommend and stayed well hydrated for the next day. My dive buddy and I drank all the beer that was left on the boat on the ride back to port:smiley2:.

From that I can tell reading the conference proceedings, they probably didn't address the "Your Dive Computer fails - Now What?"
issue because that wasn't the goal of the conference. They will probably have to hold another one to answer that question.

Davetowz
06-15-2010, 20:44
My dive buddy and I learned tables in our O/W. We also discussed computers. We did Puters / multilevel in conjunction with our AOW. we are now at 24 dives and still run tables before and after every dive and compare to our puters. I think it has helped us understand what we are seeing from both and to understand the limitations of both methods. Maybe we are different, but we want to keep good practices early and then drift into bad habits! LOL

Rorschach
06-21-2010, 07:15
Looks like you're right. I missed this too using dive computers and redundant dive computers for as long as we have now.

DAN Divers Alert Network (http://www.diversalertnetwork.org/medical/faq/faq.aspx?faqid=54)

This may even further reinfoce 12 hours as the DAN standard 'fudge factor' since by the PADI tables only, you're a new diver after 6 hours per the tables. there is undoubtably a lot of number crunching that goes along with that.

However, it begs the question why DAN published a last option if you have no other means of approximating your RNT or repetitive dive group to be an 18 hour surface interval before resuming diving, and not anything to do with air travel associated with the "Your Dive Computer fails - Now What?"

Puzzling . . .

Everything else is laid out in 6 hour increments past that point, except it's extremely vauge on appropriate SI after dives with mandatory deco stop obligations.

For ourselves, we've always used the greater of 24 hours OR the time to desat as per the algorithm in our dive computers, which as I mentioned, can exceed 24 hours even on trips where all our dives were made within NDL computer limits.

Well, I think I have this sorted out after getting my hardcopy AD mag back in my hands and some time away from work this weekend to go back through it..

Quoting from Page 91 of the Spring 2010 Alert Diver issue:

"If circumstances require you switch to a 'fresh' machine, says eric Douglas, director of DAN Education, a ddiver will need an extended surface interval to allow his body to offgas accumulated nitrogen. 'I would follow the flying-after-diving guidelines before considering myself clear enough to start over', he says. Those recommendations call for a minimum 12 hour surface interval for a single no-decompression dive or a minimum 18-hour interval for multiple dives or multiple days of diving."

I still see that DAN position as plenty conservative considering if tou're staying at roughly the same elevation relative to sea level, and are below the 8,000 ft. altitude most commercial jet aircraft cabins are pressurized to, the differential pressure in your body vs. the ambient atmosphere while you're still performing the diving portion of your dive trip lis lower than if flying-after-diving.

LeeParrish
06-21-2010, 19:57
Makes sense, I mean if the surface interval is good enough to fly, it should be good enough to start with a new computer. Glad to get that cleared up. It's funny though how many people still have the old 24 hour number stuck in their head. Was diving this weekend and someone was saying "You'll lose the entire last day of your dive trip since you can't fly for 24 hours". The 18 works out pretty nice, since if you do morning dives to say noon, you can still fly out as early as 6 AM the next morning and still have a full 18 hours elapsed. Makes 4 day trips much more like 4 day trips rather than 3 with a day hanging out all day.