Dive tables take a back seat in SSI training

[sweatfrog]

All you have to do is complete one multi-level dive with a maximum depth that would be a table violation with a square profile (which is what happens with the vast majority of resort area dives) and you won't be able to use the tables accurately the rest of the day.

You just don’t know what you don’t know. No matter which set of tables you use, you can do a multilevel dive with them.

Let’s take a dive below 80 feet for 20 minutes. Depending on which table you use, you come out with a pressure group. That pressure group is applicable for all depths on that pressure group designation. So, use that pressure group to ascend to 40 feet.

You’ll notice that your time for that pressure group has increased accordingly. Now if you want to dive for an additional 10 minutes at 40 feet, you just add that to your time stated at the 40 foot depth under said pressure group and voila; you have done a multilevel dive with the tables.

 

[explorer08]

All you have to do is complete one multi-level dive with a maximum depth that would be a table violation with a square profile (which is what happens with the vast majority of resort area dives) and you won't be able to use the tables accurately the rest of the day.

I didn't remark it before, but I became aware of it right now.
I think boulderjohn didn't mean "a maximum depth" but "a maximum time". Because the depth is usually not the problem. But what usually will happen while doing multilevel dives with computers is, that the maximum times of any table will be exceeded by far. And because of that no table can help you if your computer fails.

 

[sweatfrog]

Because the depth is usually not the problem. But what usually will happen while doing multilevel dives with computers is, that the maximum times of any table will be exceeded by far. And because of that no table can help you if your computer fails.

Well, the Navy Dive table (for one) has pressure groups for decompression diving and if you look at my last post, you'll see that will work even though the diver is in decompression. S/he is off-gassing as the ascent is made and the new depth is reached.

Decompression tables and computers both use geometric progression to find how much nitrogen has been absorbed in the body. As time passed, a lot of tables have been made more conservative with the advent of doppler systems, to measure those silent bubbles.

 

[SailNaked]

I love it when someone says you can not use the tables or a computer accurately. the word does not apply, the tables and the computers are all based on an inaccurate system of approximations. there is nothing wrong with using computers all morning and then the tables in the afternoon.
all you need to go from a computer to a table is to look at the plan feature on the computer and write down a depth and a time at that time and then compute the pressure group using a table. You are as accurate as you would be at any other time using either a computer or table which is to say not. a good practice would be to do that before every dive and write it on your slate.

PLEASE READ AND UNDERSTAND any system you use to determine your dive time

read the disclaimers that come with your tables or computer you are not guaranteed not to DCS using them. you are guaranteed to DCS doing anything I say so I can not be responsible if you do.

 

[Dive Hawk]

Never mind.

 

[glbtrekker]

SSI's recent decision to stop teaching tables is one of the reasons that I just went with NAUI for OW instead. Sorry...I just believe that a person should understand some of the theory and math that determines how long he or she can stay underwater instead of just depending on a computer and having no idea what drives the figures it displays. It's kinda like, teach my kid to add and subtract before you give them a calculator.

 

[Ch3stnut]

Hey,
I am an SSI instructor in Australia and haven't heard about not teaching tables. We still teach that unless you have a back-up comp that tables can be very important even though that still only really DC's and instructors know how to use them.

 

[PvtStash]

or at least a convenient Fringe benefit?

I mean, if you teach the tables and your student has a solid, working understanding of same, it makes it more difficult to sell them the lastest Suunto.

 

[D_B]

Nope, dont believe that's about selling computers

It's far more likely that a new diver will see that using a computer is .. easier, allows more NDL time because of the accurate "infinit" level depth/time tracking, and it a piece of "cool" scuba gear ... and it's about teaching what someone will be most likely be using the most

A cheap citizen duplex knockoff watch is what I got to back up my dive computer for trips that involve 5 dives a day, etc

 

[NAM001]

ITS A 2 EDGED SWORD. If folks use the puter as muych as they yak on the phone they would be as familiar of the putter as thier phone. when they call someone and get a wrong number they know. when they get bogus data fron the puter can you say the same??? if you dont know the tables or basic theory then there is nothing to compare the puter results to. I dont mean specific info but general stuff like. The deeper i go the less ndl time i should have. 30 min ndl at 60 feet does not mean that i will have 1/2 time at twice the depth.

The 2 go hand in hand. The tables are good for planning events like max botton time based on square profile ect. the puter will work in reality.

Tech diving should not be the first time the tables are seriously looked at in relation to deco.