Dive tables take a back seat in SSI training

[mitsuguy]

What is preventing you from teaching that? Why do you need tables to explain how nitrogen goes into and out of tissues as divers descend and ascend? Why can't you explain how a computer measures that?

because there is no easy visual...

without breaking out the tissue compartment charts, there is nothing that shows where a diver is on a chart of any sort...

you are essentially left with telling them that the deeper you go, the faster you absorb nitrogen, and the shallower you are, the slower you absorb nitrogen, which holds true, but is not the way many people think of it... no matter what it seems, without some sort of chart, people (even experienced divers even) don't see the correlation with why it takes so much more time for a diver with more time at less depth than it takes for a diver with less time at greater depth... a quick for instance, if you will... if you spend half of your maximum dive time (PADI table) at 100 feet (10 minutes), then it takes 1:28 minutes to become an A diver, and in 4:28 minutes, your body is completely washed of nitrogen, per the table, at least, and you start your next dive as if you hadn't been diving that day. However, if you use half of your maximum dive time at 40 feet (70 minutes), it takes 2:31 minutes to become an A diver, and 5:31 minutes to become washed completely, per table again. So, without getting into tissue compartments and charts, the tables are an easy way for someone to visually see the ins and outs.

Here's another great example... With my computer, I have dived to the no decompression limits, and beyond. Doing a single deep dive, I find that I am washed of nitrogen, according to the computer at least, usually later on in the day, sometimes late that evening. However, if I do multiple, easy, shallow dives, I sometimes find myself with nitrogen still in my system well into the next day, even though I never even got close to my ndl's... It's almost as though you have to tell a diver to "just trust the computer" without giving them any information as to how it works...

Now that I think about it, it is probably easier to teach the tables than it is to try and explain why a dive computer works the way it does without the tables.

Generally, I find that once a student learns the tables, showing them how a computer works (I usually let them dive one on dive 3 or 4 of check out dives) is relatively simple, and they then understand the "why."

One great argument given is that many students simply don't retain the tables. I have nothing to argue with against that, because I do see it all the time. Given current training standards and the way most people dive (just a few times a year), I don't see a way to remedy this.

 

[mitsuguy]

While much is made in the dive community of the dangers of DCI, DAN's latest 2008 report has a section which reviews DCI incidents. In one major study, they say recreational divers reported 3 incidents in about 15,000 dives. This seems fairly low to me, and indicates that the almost universal use of computers is not a problem.

There are a lot of people that get LUCKY!

A while back, we had a large group of divers. The two divemasters we had on the boat briefed the second dive of the day carefully, because the depths could put some people close to their limits on their computers... As they briefed the dive, they said for everyone to watch their computers, ascend to a shallower depth if they started getting low on no-deco time, and to make sure they followed their computers if any ndl's were surpassed.

As the divers came back to the boat, our DM's remained in the water, showing people little things around the mooring, waiting on others to do their safety stops and whatnot. Neither of our DM's went into deco (and one dives a Suunto even). Back on the boat, with all divers out of the water, it was found that some divers ignored 8 minute deco stop warnings from their computers. Ones comment was something along the lines of "it said something about an 8 minute ascent time, so I just did my 3 minute stop and came up" This guy had plenty of air. He was not the only one of the bunch to do this. The divers completely ignored the warnings and times given on their computers and dived deeper for longer than our divemasters (who are always first in the water, last out).

I truly believe luck plays a big part in keeping that number so low.

 

[Bogie]

Dive computers are the current standard for diving. If you use the dive chart you get short dives and unrealistic dive profile. I know my dive computer well now but it would have been nice to get some training. I like knowing dive tables and learning dive tables is easy so I would teach both. Probably the vacation diving crowd would never look a dive table and probably don't need to.
Technical diving is another world and those divers need to know their stuff.

 

[boulderjohn]

because there is no easy visual...

without breaking out the tissue compartment charts, there is nothing that shows where a diver is on a chart of any sort...

Why do you need a chart?

I teach decompression theory in the beginning with Boyle's Law. It makes sense there. I teach tables later on, but they have the theory down long before that.

My students have no trouble understanding it.

 

[boulderjohn]

There are a lot of people that get LUCKY!

A while back, we had a large group of divers. The two divemasters we had on the boat briefed the second dive of the day carefully, because the depths could put some people close to their limits on their computers... As they briefed the dive, they said for everyone to watch their computers, ascend to a shallower depth if they started getting low on no-deco time, and to make sure they followed their computers if any ndl's were surpassed.

As the divers came back to the boat, our DM's remained in the water, showing people little things around the mooring, waiting on others to do their safety stops and whatnot. Neither of our DM's went into deco (and one dives a Suunto even). Back on the boat, with all divers out of the water, it was found that some divers ignored 8 minute deco stop warnings from their computers. Ones comment was something along the lines of "it said something about an 8 minute ascent time, so I just did my 3 minute stop and came up" This guy had plenty of air. He was not the only one of the bunch to do this. The divers completely ignored the warnings and times given on their computers and dived deeper for longer than our divemasters (who are always first in the water, last out).

I truly believe luck plays a big part in keeping that number so low.

What this shows is that they were not properly instructed on how to use their computers. Perhaps that would have been a good thing to do in their instruction.

 

[waterpirate]

Bingo!
Four pages later we get to the real issue. It is the quality of the instructor/instruction, not the method used. The concept of tables vs. computer is moot, if either method is taugt thourougly. It also has nothing to do with agency. Any quality instructor teeaches well beyond the standards, which could be compared to a ged vs. a diploma from a privat academy.
I recently went with a old friend, new diver for a drysuit course. Prior to entering the water I asked the instructor what the dive plan was and got deer in the headlights. I asked my friend what was the max depth available in the quaurry and if he attained it what was his max ndl time. I got a blank stare. I blame this on the instructor solely.
As a foot note when my freind returns from Afganistan I will mentor him and straighten him right out.
Eric

 

[Sask Diver]

This just seems to confuse me even more, I am taking my ow in Feb and a freind of mine has tried explaining the dive tables to me before the course, now my instuctor says PADI does not instuct with the dive tables anymore but with eRDP. Is this a safe way to go, am I supossed to trust my life to a $10 peice of electronics and a 25 cent battery.
If there is one thing I want to get down pat, it would be the dive tables so I will be around to enjoy many years of diving in the future.

 

[waterpirate]

This just seems to confuse me even more, I am taking my ow in Feb and a freind of mine has tried explaining the dive tables to me before the course, now my instuctor says PADI does not instuct with the dive tables anymore but with eRDP. Is this a safe way to go, am I supossed to trust my life to a $10 peice of electronics and a 25 cent battery.
If there is one thing I want to get down pat, it would be the dive tables so I will be around to enjoy many years of diving in the future.

Here is what I consider good advice about your dilema. "slow and easy with good technique". Consider your ow a learners permit. Learn what you can in ow and never stop learning. Find divers in your local area who dive alot, dive with them. Someone in the group will mentor you and fill in alot of questions with practical knowledge. Take more classes and dive,dive,dive.
Eric

 

[clint@uniquescuba.com]

Except for the fact that PADI has been advocating this since mid 2009... They even changed some quizzes and knowledge reviews to reflect the change..

LOL...so!

This was also a huge "Tip of the Hat" to SDI as well

How many of you know how long SDI has been doing this??? 2 years? 5 years? 10 years?


I also think it was absolutely hilarious in SSI's press release they stated "We hope you are excited about this change as we are! SSI will continue to bring you these types of innovations to help you stay on the cutting edge of training and education."

cutting edge and innovative!.....lol.... I'm about to pee myself this is so funny, making a statement like that when your like 10 years behind SDI

 

[boulderjohn]

This just seems to confuse me even more, I am taking my ow in Feb and a freind of mine has tried explaining the dive tables to me before the course, now my instuctor says PADI does not instuct with the dive tables anymore but with eRDP. Is this a safe way to go, am I supossed to trust my life to a $10 peice of electronics and a 25 cent battery.
If there is one thing I want to get down pat, it would be the dive tables so I will be around to enjoy many years of diving in the future.

Relax.

There are many ways to plan and track dives. Tables are one way. Computers are another way. The eRDPml is another way. Dive planning software is still another way.

I taught the tables for years. They work. The eRDPml has only come out recently, and I have only taught a few classes in which students learned that way. They learned the eRDPml much easier than past students learned tables. They made far fewer errors. We were able to practice planning far more complex dives in class without the computational errors so common in table practice. (With tables, it is really easy, for example, just to read the wrong number because they are so small and close together.)

Don't worry about it. The important thing--as mentioned above--is to understand how decompression works and why you have to do the things you have to do. Once you are more into diving, you will make a choice as to how you will plan your dives. In all my years of vacation diving, I have rarely seen anyone pull out tables of any kind for recreational diving, so the odds are you would have gone away from them to something else--like a computer--anyway.

If you get into more complex decompression diving, neither the normal tables nor the eRDPml work anyway, so you will have to change.