PADI tables finally going away?

[tridacna]

I was reviewing the tables with a new open water student and found a large discrepency between two different ageny's (PADI and SSI) tables both had comprable bottom times but the surface intervals were over and hour and a half different. weren't all tables based on the navy dive tables? if so why the difference?

Can you be specific here? What were the BTs, Depths and SI in each case?

 

[muddiver]

SSI's tables are based on the U.S. Navy dive tables of 1995 and dopler bubble work. The surface interval is much more conservative due to the dopler research.

The PADI tables are not based on the U.S. Navy tables. PADI via DSAT did their own research and created a different set of algorithms to produce the PADI Dive Planner. You must understand that before you try to compair them.

If you want to really see conservative, punch HUGI tables into Google and check out the table that the University of Southern California uses that is based on extensive doppler bubble research.

Also note that the Navy has revised the Diving Manual and it includes an extensivly revised set of diving tables. Most of the No-Decompression diving requires oxygen stops, there is a new shallow depth table with more depths inbetween the older 15 foot incriments and there is an altitude equavilant depth table.

 

[boulderjohn]

I was reviewing the tables with a new open water student and found a large discrepency between two different ageny's (PADI and SSI) tables both had comprable bottom times but the surface intervals were over and hour and a half different. weren't all tables based on the navy dive tables? if so why the difference?

No.

PADI tables were based on their own independent, published research. They are not based on Navy tables at all.

 

[imwright1985]

What does it matter, if you know how to read tables you can tell about when you will hit surface so when on a boat the spotter will know when to keep an even stronger lookout, if you know how to use your computer they allow a planner mode which takes over from that use for the table too. The computers do close to on the fly calculations for remaining time and provide you with all your safety reminders too, If you have the cash for a comp and take a week to learn it well i think it surpasses using tables but knowing atleast how to use a set of tables is easy and always a good thing

 

[leabre]

Well.... I've used PADI tables for about a year and a half after my certification (about 40 dives, got certified in 2008). I find the table to be really intuitive, but maybe that's because I'm a computer progammer and it kinda fit the way computers operate. I've even used an EAD table I built in excel myself (not that it's hard) so that I could dive nitrox on a trip where I didn't have a nitrox table (complete with ppO2 info, ...), gotta say the DM and fellow divers on that boat weren't sure what to think of that. I was the only diver without a computer.

I haven't read all the posts yet. I'm a programmer also, and I don't usually have a problem with the tables myself except that they are designed for square profiles and without the PADI wheel or e-RDP ML, there isn't an easy way to use the tables to get credit for shallower depths. Hence, I use the computer. Nearly all my profiles are shore entry, so I go shallow to deep, then slowly back to shallow. A typical dive for me will be 100+ minutes with max depth of 80'. My computer has no problem with it, the e-RDP ML has no problem, and neither does the Ratio Deco strategy.

After taking UTD Essentials, we learned a completely different twist on the tables. In fact, after a few short (or long) hours studying the reasons, I have the table memorized, as well as its operations. Nothing to memorize, it just makes sense.

It is simple: the tables is based on the US Navy tables but with some conservation in some areas. You normally ascend at the rate of 30 ft. per minute until the 50% depth of your deepest. From there, you ascend at the rate of 10 ft. per minute (or ascend 10 ft. and hold a minute, or 30 seconds with 30 ascent, however you want), until you surface. But your NDL is based on your average depth. Your off gassing (deco) is factored into the ascent strategty and we do not stop at 15' for 3 minutes. We use deep stops instead (as described above).

So if I do 80 ft. for the first 5, then spent the rest of the majority of my dive at 35-40 ft. for say, 90 minutes, then your average is likely to be close to 40 ft overall, give or take, so your NDL on the UTD air tables is 170 minutes, so you're well within the limits.

Make a 1 hour minimum SI, then can repeat the dive. Less than 1 hr SI, then make your 30/20/10 stops 2 minutes instead of 1. There are no pressure groups, no residual nitrogen, etc. The table is simple, easy, and consice enough to do in your head (even at depth) though you will plan the dive before entering the water to some extent (mainly for determining volumes and Rock Bottom volumes/pressures).

I have since put my computer in guage mode and use it as a timer and to record my dive profile. People would prolly look at me funny for not using tables or computers, though I'm using the "computer between my head"; but such is my training and the way I practice it these days. This way, IMO, is so much simpler than workin the PADI tables.

I'm not PADI trained, I was NAUI. But there is little difference in table mechanics between the mainstream agencies (including the US NAVY).

This is how it is taught in UTD Rec1 (Open Water) as well, as far as I know.


Thanks,
Shawn

 

[Rainer]

I have since put my computer in guage mode and use it as a timer and to record my dive profile. But, I am deeply tempted to replace it with a watch only, and my SPG.

How would you know your average depth based on only a watch and SPG?

 

[leabre]

How would you know your average depth based on only a watch and SPG?

Sorry Chris... by intuition? Good point. Some watches have depth guages but are not computers. My only caveat would be losing my profile recorder and downloading it. I would have to go back to filling in paper logs.

Until then, my computer in guage mode will suffice.

Thanks,
Shawn

 

[Rainer]

All the Suunto computers still record the dive in gauge mode. Or buy a Sensus Ultra. They're really cheap. What computer do you have that won't record in gauge mode?

P.S.
A watch with a depth gauge IS basically "gauge mode".

 

[leabre]

Rainer, my computers record just fine in guage mode. I meant a watch with depth indicator most likely would not record the dive profile. No need to make it more complicated, just that a computer to be used in guage mode ($300+) seems expensive to me. I could put my money into other areas of tech diving. I'm using a Gekko and Vytec DS. Usually the Gekko.

 

[Rainer]

But a watch with depth gauge that is reliable (and easy enough to read so you can get an accurate average depth) is probably going to cost at least that much, and you lose the data logging.

A used Vyper can be had for <$200. Used Uwatec BTs are around $100. That Vytec DS you already have is perfect (I know, I have and use one). It's easy to read, has seconds in gauge mode (resettable), user replaceable battery, downloadable, wrist mounted, fits a DSS bungee mount, backlight, etc.

I just don't see any savings for a decent dive watch with depth gauge over a dedicated bottom timer (with more and better features).

Rainer, my computers record just fine in guage mode. I meant a watch with depth indicator most likely would not record the dive profile. No need to make it more complicated, just that a computer to be used in guage mode ($300+) seems expensive to me. I could put my money into other areas of tech diving. I'm using a Gekko and Vytec DS. Usually the Gekko.