Diving Tables???

[Dive-aholic]

Thanks everyone!

I would then dive the most conservative tables.

A computer must be programmed with a set of tables, anyone know which tables they use to programm it?

thanks again.

Computers are based on models, not tables, just as tables are based on models. To answer your question, it depends on the computer. There are three basic models the manufacturers use. You should be able to find the model the computer is based on in the owner's manual.


A quick comment on the wheel. I have used it to plan recreational multilevel dives for gas management. It's really useful for that. With a little bit of work, you can also use a table to plan multilevel dives. It's a little more time consuming and doesn't give you the 5' depth increments, but it is possible.

 

[pablovi]

Computers are based on models, not tables, just as tables are based on models. To answer your question, it depends on the computer. There are three basic models the manufacturers use. You should be able to find the model the computer is based on in the owner's manual.


A quick comment on the wheel. I have used it to plan recreational multilevel dives for gas management. It's really useful for that. With a little bit of work, you can also use a table to plan multilevel dives. It's a little more time consuming and doesn't give you the 5' depth increments, but it is possible.

Thanks! So, which computers are more conservative?

I don't know, I've never dive with a buddy, just my Open Water instructor, that's why I have so many questions. In the book it says, never share a computer, each diver must have one, and it also says, always dive with a partnert and never lose sight of him/her, and always descent and ascent together. So, if we have different dive computers and mine say to go up and his doesn't does he needs to go up with me? or do I wait for him?

 

[Meng_Tze]

Thanks! So, which computers are more conservative?

I don't know, I've never dive with a buddy, just my Open Water instructor, that's why I have so many questions. In the book it says, never share a computer, each diver must have one, and it also says, always dive with a partnert and never lose sight of him/her, and always descent and ascent together. So, if we have different dive computers and mine say to go up and his doesn't does he needs to go up with me? or do I wait for him?

Safety says, stay with your buddy. Not sharing comes from two parts: if you share one computer and it fails/gets lost, you both will have an issue. Second, in extreme instances your actual profiles may be different, so having one compure could put one of the divers in a ascent profile that is not condusive to offgassing appropriately.

In reality, given the conservatism nowadays (litigation potential) in the computers, if you are in a situation where one computer says go up, and the other still has time remaining, I would stick with the most conservative one. Within NDL there should not be an issue.

 

[Iruka]

Just a consideration in using "the most conservative table" to plan a dive. If you use, for example, the PADI square dive table for a 100' dive, you get only 20 minutes of bottom time. If you're okay with that, great.....but (assuming it's not a square profile dive) everyone else using a computer, or the wheel, or ANYTHING that takes into account multi-level diving might be getting back onto the boat 20~40 minutes later. Statistically, I suppose you might be slightly safer in always doing short dives, but millions of people dive safely without using a "consider the entire dive to be at the maximum depth" approach. (I'm aware of the method of using the square table to plan multilevel dives, though it's not meant to be done that way....though the numbers you come up with will be very close to those using the wheel.)

 

[Quarrior]

Thanks! So, which computers are more conservative?

I don't know, I've never dive with a buddy, just my Open Water instructor, that's why I have so many questions. In the book it says, never share a computer, each diver must have one, and it also says, always dive with a partnert and never lose sight of him/her, and always descent and ascent together. So, if we have different dive computers and mine say to go up and his doesn't does he needs to go up with me? or do I wait for him?

As time goes by and diving experience grows you'll find many different kinds of divers out there.

Some will be people that believe in adhering to the buddy principle strictly. Some will be "same ocean buddies" (SOBs). Some will dive their own computer and give you a thumbs up when it tells them to or follow you up when you give them the thumbs up. While others are "solo" divers.

As for which computer is the most conservative, the Suunto line is pretty conservative.

In investing in a computer you should get one that does both air and Nitrox. Also ensure the amount of Nitrox can be set in single digits, ie 31 versus 32 percent. Some only allow for 2% increments.

Some computers are AI integrated, which will tell you what psi is in your tank. These are great, but always make sure you have a good old SPG too for a back up. Underwater is not a good time to find out you have a dead battery on either the transmitter or the computer itself.

 

[Charlie99]

Just a consideration in using "the most conservative table" to plan a dive. If you use, for example, the PADI square dive table for a 100' dive, you get only 20 minutes of bottom time. If you're okay with that, great.....but (assuming it's not a square profile dive) everyone else using a computer, or the wheel, or ANYTHING that takes into account multi-level diving might be getting back onto the boat 20~40 minutes later. Statistically, I suppose you might be slightly safer in always doing short dives, but millions of people dive safely without using a "consider the entire dive to be at the maximum depth" approach.

Iruka, I bet you have less than half a dozen "standard profiles" you use. Such as 80' 15 minutes, 60' 15 minutes, rest of dive at 40' or less. These standard profiles are suitable for typical recreation divers both in deco and in gas consumption from an AL80. They are completely off the chart if plotted on a square profile table, but are how diving is really done in areas suitable for multilevel dives.

As you say, millions of dives are done this way each year. These multilevel profiles are in many ways much safer than square profile. The problem is that most divers don't have any way to plan such dives.

At some point, I'll get ambitious and put together a handful of standard profiles (including good 2nd dives with 1 hour SI) and post them ---- unless you and other working dive guides want to jump in and post your tried and true profiles.

 

[Cacia]

yea, do that! great idea.

 

[Iruka]

Iruka, I bet you have less than half a dozen "standard profiles" you use. Such as 80' 15 minutes, 60' 15 minutes, rest of dive at 40' or less. These standard profiles are suitable for typical recreation divers both in deco and in gas consumption from an AL80. They are completely off the chart if plotted on a square profile table, but are how diving is really done in areas suitable for multilevel dives.

As you say, millions of dives are done this way each year. These multilevel profiles are in many ways much safer than square profile. The problem is that most divers don't have any way to plan such dives.

At some point, I'll get ambitious and put together a handful of standard profiles (including good 2nd dives with 1 hour SI) and post them ---- unless you and other working dive guides want to jump in and post your tried and true profiles.

That's basically correct....I did my first 2,500 dives or so without ever using a computer...and used the PADI wheel to plan multi-level dives. My next 3,300 dives I've mostly used a computer, unless I need to use a dive table or wheel in a class or something like that. And of course, the common shallow dives (30~40 feet) don't really have nitrogen loading as a consideration. Back when I used the wheel, I'd tend to have a standard profile or two for each dive site....mostly depending on the terrain there.

 

[miketsp]

The big problem with most of these tables is that they stop at 39m.
Exactly where things start to get interesting.
The tables I carry in my BC pocket, for those special occasions, should cover the unexpected.
So I stick with my CMAS tables which run to 63m.

 

[Meng_Tze]

Just a consideration in using "the most conservative table" to plan a dive. If you use, for example, the PADI square dive table for a 100' dive, you get only 20 minutes of bottom time. If you're okay with that, great.....but (assuming it's not a square profile dive) everyone else using a computer, or the wheel, or ANYTHING that takes into account multi-level diving might be getting back onto the boat 20~40 minutes later. Statistically, I suppose you might be slightly safer in always doing short dives, but millions of people dive safely without using a "consider the entire dive to be at the maximum depth" approach. (I'm aware of the method of using the square table to plan multilevel dives, though it's not meant to be done that way....though the numbers you come up with will be very close to those using the wheel.)

Agreed, when planning a dive you take in consideration BT, avg depth etc. But when it comes to two divers coming up, one lost track of obligations (for whatever reason), would it not be safest to use the most conservative table to get out? (given that it is a NDL dive)