Info Why are tables not taught in OW classes anymore?

[ChrisDee]

There is a whole thread on the "rule of 120" and its variants. No need to repeat ie here.


What is your point about the rules?

The thread is about why tables are rarely taught in OW classes today. Thr bottom line is because tables are mostly for square profiles, and that is not the kind of diving most recreational divers do. Teaching tables is like drilling students on pulling the rod on a J-valve. We don't do that anymore.

My point about the rdp table "Rules" is there is actual knowledge there that you needed to modify your results from the tables, needed to take into account other items as compared with just time and depth.

You need to think. Not you,...I was alluding to too many take the easy road and give up thinking,....IMO by learning the tables,...people think more, and remember more,...

No one does this with computers.

I was agreeing with you,...

 

[lowwall]

I just read this whole thing.

Seriously guys / one gal,....some moderator should end this.

The thread had been dormant for almost a month. If you think it should be ended, why did you restart it?

I'm not just being flippant. Your answer to my question, whatever it may be, is exactly why this thread continued on for so long.

 

[BoltSnap]

The thread had been dormant for almost a month. If you think it should be ended, why did you restart it?

So if ones sees something wrong or doesn't agree with, they just should shut up because a thread is a month old??? What about the Zombie threads from a decade ago, execute whoever adds a post to these threads???

Come on, you surely can come up with a better post.

 

[lowwall]

So if ones sees something wrong or doesn't agree with, they just should shut up because a thread is a month old??? What about the Zombie threads from a decade ago, execute whoever adds a post to these threads???

Come on, you surely can come up with a better post.

Your missed my point completely. I suggest you read the second paragraph of my post and think about it for a bit.

 

[BoltSnap]

Your missed my point completely. I suggest you read the second paragraph of my post and think about it for a bit.

Come on, this is the internet, if it takes more than few second to understand what you wrote, you obviously didn't write it clearly. You have to do better.

 

[lowwall]

Come on, this is the internet, if it takes more than few second to understand what you wrote, you obviously didn't write it clearly. You have to do better.

You are probably right.

 

[Umpman]

I have recently done diving with instabuddies and they don’t have dive computers. Multiple dive centers just directed to stick together and “share my computer”. In these cases we have not gone close to ndl, they have been fairly shallow dives. Probably 80ft max, 40ft average, bottom time around an hour. And the dive master has stayed close to us and also watched his ndl.

It seems like a fair and frequent practice. Also, is this another option for buddies that both have computers if one fails? As long as they stay close together at depth and are not approaching ndl and not pushing close to a minimum surface interval?

Wow, that’s horrible advice from the dive center. Every course I have taken days you don not share computers. In my opinion, that’s a lawsuit waiting to happen. What if one of those instabuddies was diving multiple dives the day before or even that morning. They could have a very different NDL. What if you’re on nitrox and they aren’t. All it takes is one of them getting bent and then saying “so and so said we still had more time”.

Personally, I will never dive with someone who doesn’t have a computer. If I’m hired to be a guide/divemaster, it’s a requirement. If a dive operation im working for insists, I’d quit.

And I certainly wouldn’t dive with someone who doesn’t have a computer or using similar gas as I am if i’m on a fun dive. Dives cost too much money to have to cut it short because my buddy has a different profile

 

[Umpman]

As someone who learned to dive in 1992, I learned to dive tables since computers were just hitting the market and many people didn’t trust them. When I began diving again, I took another OW course (mostly because my wife was learning to dive and I wanted to support her) but I also wanted to learn about diving with computers. I was shocked to see they didn’t even discuss tables (this was SDI) and think it’s a mistake that agencies aren’t teaching tables anymore.

Yes, our computers do a great job and give us more bottom time than if you use a table for planning. Yes, computers keep track if you are doing multiple dive days and are even more beneficial when diving several times in a week and then flying. Yes, dive computers make it easier when doing altitude diving. but we should know the basics.

Tables are not that hard to understand, especially the SSI tables, which is just “follow the arrows”. Knowing tables helps you to plan a dive, but unfortunately that is usually overlooked in OW classes too. Tables also help with figuring out how long your surface interval should be. Computers give you your surface time but most don’t tell you how long your surface interval should be before the next dive. I can’t tell you how many times I’ve been on a boat and the DM would ask a diver how long do you need for your interval and the diver didn’t know.

As a dive guide/DM, tables help me figure out a plan to go over during a briefing. Depending on which gas the client is using, I can say “we’re going to drop to 100ft, stay there for a certain amount of time, usually about half of what a table says is the NDL limit and then ascend to a shallower depth for the rest of the dive and use our computers to get the most amount of bottom time.

Also, the other problem with not at least.understanding tables is that I see people dive a wreck and start in the deck then drop lower for the later part of the dive. Because they have no idea of what the NdL is at the deeper depth is, many times they end up in deco

 

[rx7diver]

There is a whole thread on the "rule of 120" and its variants. No need to repeat ie here. ...

Well, problem is, the "120 Rule" doesn't always work:

40 for 200.
50 for 100.
60 for 60. Check!
70 for 50. Check!
80 for 40. Check!
90 for 30. Check!
100 for 25.
110 f0r 20.
120 for 15.
130 for 10.

All with a 60 [sic] fpm ascent rate.

Best to just memorize the handful of pairs of "magic numbers"!

I know, I know: My numbers are from a mid-1980's version of the Navy tables. But they're already committed to memory. Long time ago, in fact. Stay well away from NDL, and there's no problem, even if you slow your ascent rate to 30 fpm--which these days I do.

rx7diver

 

[Belzelbub]

Wow, that’s horrible advice from the dive center. Every course I have taken days you don not share computers. In my opinion, that’s a lawsuit waiting to happen. What if one of those instabuddies was diving multiple dives the day before or even that morning. They could have a very different NDL. What if you’re on nitrox and they aren’t. All it takes is one of them getting bent and then saying “so and so said we still had more time”.

Agreed completely. I've heard that from time to time and I'm just amazed that someone actually said it. I learned originally on tables, but even then, it was taught that if using a computer, use your own. There will always be variations from diver to diver. Could be small, but could also be significant. Regardless, trusting another diver, who I may have just met, with information such as this is a bit much to ask.

Tables are not that hard to understand, especially the SSI tables, which is just “follow the arrows”. Knowing tables helps you to plan a dive, but unfortunately that is usually overlooked in OW classes too. Tables also help with figuring out how long your surface interval should be. Computers give you your surface time but most don’t tell you how long your surface interval should be before the next dive. I can’t tell you how many times I’ve been on a boat and the DM would ask a diver how long do you need for your interval and the diver didn’t know.

That would depend on the dive plan for dive 2. Yes, you could find that on a table, but I could just as easily enter the planning mode on my computer. I can see what my bottom time would be right now, or in the near future.

Also, the other problem with not at least.understanding tables is that I see people dive a wreck and start in the deck then drop lower for the later part of the dive. Because they have no idea of what the NdL is at the deeper depth is, many times they end up in deco

They are both tools. While I was taught using tables, and my daughters were taught that as well, I really don't use them that much. It's just simpler for me to use the computer. The problem you describe above, doesn't really have anything to do with not knowing tables. It has more to do with not understanding the basics of decompression theory. There really is no problem hanging out on the deck for a bit, then dropping lower with either tables or a computer. With tables, you have a new max depth, to figure. Hopefully the dive time doesn't exceed. With a computer at least, the computer will recalculate. If the diver doesn't pay attention to the computer, then I really don't know what to say to that. Whatever tool you use, if you don't know how to use it, it's just not going to help you.

I can't recall the last dive I did where there was a diver without a computer. This includes OW checkout dives I did with my daughters. In fact, I'm pretty sure the last dive I did where not all divers had a computer was back before 2006 or so. And the sole diver without a computer then was me. Since then, I've converted and made sure I understood how to use these tools.