Computers versus Tables

[diverbrian]

As someone who works closely with an LDS, but who has a job and doesn't get paid by the dive shop let me throw in my experience.

All of the classes that I have sat in on for SSI and IANTD force students to learn the tables. If I am planning and executing a deco dive, I do it by the tables for EAN 28, EAN 32, or Air and by my time into the dive or rule of thirds (whichever comes first).

Our SSI open water students are not passed unless they know and understand what the tables are there for. They do their open water dives for certification by the tables.

This having been said, I have done several multi-level dives that would be impossible with tables (for example, descend to 120 ft for a minute or two and spend the rest of the dive at fifty or sixty foot along the reefs in Provo). I know this because I make a habit of figuring my letter groups at the end of my diving day to stay in practice. My recreational diving is by computer to maximize my wet time. And yes, I do keep tables if the computer breaks, but we can't go from one to the other on multi-level, repetitive diving without at least a 24 hour delay, anyways.

IMHO, if a diver has a grasp of why we use tables and what they mean, I find that it is normally to their benefit to use a computer. (And as I have already stated, I do not sell computers).

 

[Uncle Pug]

diverbrian once bubbled...
I have done several multi-level dives that would be impossible with tables (for example, descend to 120 ft for a minute or two and spend the rest of the dive at fifty or sixty foot along the reefs in Provo).

"impossible" should have been followed by "for me" since it is not impossible for everyone.

For example here are some dives from my dive log. All are multilevel dives without a computer:

Single day: 129 for 31 followed by 126 for 41 followed by 52 for 28

or

First day: 90 for 30 followed by 92 for 48

Second day: 111 for 45 followed by 104 for 41 followed by 91 for 31

Third day: 104 for 55

 

[jonnythan]

Uncle Pug once bubbled...

"impossible" should have been followed by "for me" since it is not impossible for everyone.

For example here are some dives from my dive log. All are multilevel dives without a computer:

Single day: 129 for 31 followed by 126 for 41 followed by 52 for 28

or

First day: 90 for 30 followed by 92 for 48

Second day: 111 for 45 followed by 104 for 41 followed by 91 for 31

Third day: 104 for 55

These are obviously not rec dives, as on most of them you incur a deco ceiling.

 

[diverbrian]

The tables that I use are for one depth assuming that I stay at that depth on a square profile. Sorry, but the minute I drop down to between 120 and 130 ft. I am immediately limited to the time indicated on that table. That means that if I descend to 122 ft I am limited to say 12 minutes no deco time until I start my direct ascent (EAN28). This is true even if I ascend to 50 ft after a minute or two at depth. If I want to stay longer, I am in deco by my table. No exceptions exist to this by my training and none of my instructors have even hinted at ways to account for the depth change except to (1) ascend in the twelve minutes as if the whole dive was spent at the 120-130 ft range and lose the bottom time or (2) use a dive computer. Maybe they know ways, but they aren't telling the students and they don't seem to figure multi-level dives without the dive computer.

 

[Uncle Pug]

jonnythan once bubbled...
These are obviously not rec dives, as on most of them you incur a deco ceiling.

None of those dives incurred a deco obligation.

 

[Uncle Pug]

diverbrian once bubbled...
Sorry, but the minute I drop down to between 120 and 130 ft. I am immediately limited to the time indicated on that table.

Maybe they know ways, but they aren't telling the students and they don't seem to figure multi-level dives without the dive computer.

I just wanted to expand your thinking a little. From your post in another thread:

I don't want to limit it by listening to ONLY one school of thought.... closed mind can cause serious problems.

BTW... they probably don't know the way.

 

[jonnythan]

Uncle Pug once bubbled...

None of those dives incurred a deco obligation.

If you're at 129 feet for 31 minutes, you have a deco ceiling.

Unless I've completely missed something obvious..

 

[O-ring]

jonnythan once bubbled...


If you're at 129 feet for 31 minutes, you have a deco ceiling.

Unless I've completely missed something obvious..

...and that was just his max depth.. I don't think UP does too many square profiles..

 

[Uncle Pug]

jonnythan once bubbled...
I've completely missed something obvious..

Uncle Pug once bubbled...
All are multilevel dives...

 

[jonnythan]

Uncle Pug once bubbled...

I misread. Apologies