What back-up tables?

[nickjb]

What tables are people using for back-up? I use my computer (suunto) for rec diving but would like to start carrying back-up tables. I started with PADI but the RDP doesn't do deco and I've read the BSAC 88 tables aren't that good.

A link to something I can print out would be nice.

 

[O-ring]

You can print out backup tables in decoplanner and actually adjust the time/depth increments. That way, if you overstay (or understay) your planned bottom time or accidentally end up deeper (or shallower) you have a bailout table handy.

 

[SDAnderson]

Unlike recreational NDL tables, once you cross into deco the tables (and the dives) get very complicated very quickly. There are a substantial number of variables that must be accounted for: in addition to depth, time and gas(es), you need to think about what algorithm you want to use to calculate your decompression obligation, how conservative you want to be, what ascent rates you're going to use, will you be doing deep stops, where will your gas switches be, etc, etc.

The tables that you read about divers using for decompression are typically software generated and specific for each dive - there isn't a table or set of tables like the PADI RDP or simliar recreational tables. They will include all of the above factors, plus bailout information (to accomodate unexpectedly short or long dives) and are printed or transcribed to waterproof paper.

From your post and profile, I'd guess that you're just beginning the process of looking at decompression diving and I'l like to urge you to be very careful. This stuff may seem like it can be book learned, but it really can't. In addition to the books, you need an old salt to walk you through it a bunch of times. Mistakes will kill you or hurt you so badly you'll wish you were dead.

There are a number of different applications out there that will do deco calculations. The most popular seem to be Decoplanner, GAP, and V-Planner. They aren't all the same, most divers seem to have tried multiple applications before settling on one that they like best.

Search this board for deco software - there have been tons of threads that can teach you a lot about the various software packages and deco diving in general.

Steven

 

[exnewwavedivers]

Most likely, you're planning or have done decompression dives using a computer. Before buying a backup table, visit your LDS and ask about courses that allows you to do decompression dives.

 

[Rick Murchison]

When you take your Advanced/Deep Nitrox and Decompression Diving courses you'll get tables as part of the course.
You are taking the courses before decompression diving.
Rick

 

[nickjb]

When you do even a basic BSAC course you learn about decompression diving. Some might argue that all diving is decompression diving. The standard BSAC tables seem a little dated to me and while they do cover decompression they can't take recent deco theories into account. I was interested in what other members of the board do. It seems most people (here and on another board I posted the same question on) seem to prefer to cut their own tables. Is everyone really doing such wildly different diving that they have to keep recreating custom tables?

 

[O-ring]

1) On your BSAC comment - same with CMAS. One of the guys I dive with is from France and he has French deco tables that were given to him in his level 1/basic class.

2) Not really on the custom table thing. A lot of my diving is similar and I can use the tables over and over. For example, most of the dive ops I dive with down in NC bank EANx30 and most of the wrecks are in the 100-120' range. I can cut backup tables for depths between 60-130 feet on EANx30 with a time range from 10 mins to 40 mins and have 99.9% of the potential bailout I would need.

 

[padiscubapro]

O-ring once bubbled...
1) On your BSAC comment - same with CMAS. One of the guys I dive with is from France and he has French deco tables that were given to him in his level 1/basic class.

2) Not really on the custom table thing. A lot of my diving is similar and I can use the tables over and over. For example, most of the dive ops I dive with down in NC bank EANx30 and most of the wrecks are in the 100-120' range. I can cut backup tables for depths between 60-130 feet on EANx30 with a time range from 10 mins to 40 mins and have 99.9% of the potential bailout I would need.

You are given just the most basic information.. decompression diving is not to be taken likely.. hook up with an experienced technical instructor.. following a computer or tables blindly is a disaster waiting to happen.. ANy time you are deco diving you must plan contingencies since there is no option to surface.. you must treat all deco dives as though you were in an overhead enviroment with no direct ascent to the surface.

The more deco dives you run the more you will become familiar with your common profiles.. many of the dives I do I have no need to carry any tables (they are written down anyway, as a precaution) with me since I have done the profiles so many time I know what my stops are supposed to be...

If you are asking these questions you are already admitting you don't have enough training.. A good instructor will explain the different deco theories that are currently being used and explain how different programs differ and why..

I personally like Vplanner, this generates probably the absolute minimum deco required of any program but with it comes many issues.. The profiles must be followed EXACTLY (up to the last stops which can be extended) any deviation from ascent rates causes the profiles to become invalid..
let me pose a few questions to you, and honestly answer if you thought about these..

Do you have a PFO??
Do you carry a backup mask and why??
Do you have a means of a stable deco platform if an ascent line can't be found??
Do you know how much gas you will need to complete your deco before the dive or how much bottom gas you will need??
If you answered I don't know or I never thought about it, to any of these more training is definately in order..
These are just some of the issues that should be covered in a good deco class..

 

[O-ring]

If you are asking these questions you are already admitting you don't have enough training..

I don't know that I asked a question. Just stated that you can do backup tables with Decoplanner.

Do you have a PFO??
Do you carry a backup mask and why??
Do you have a means of a stable deco platform if an ascent line can't be found??
Do you know how much gas you will need to complete your deco before the dive or how much bottom gas you will need??

You bring up good points anyway...let's talk about them.

1. I do not know if I have a PFO as I have not been tested. Am I planning to get tested? No. I say keep it conservative...dive like you have a PFO. I wouldn't quit diving if I tested positive anyway...

2. I don't carry a backup mask since I dive with a like-minded buddy and do not do any diving where that is a requirement yet in my diving career (significant overhead).

3. Does a liftbag and spool count as a stable deco platform?

4. Gas management calculations are a regular part of every serious dive. Do I do them on every dive? No...

 

[nickjb]

He may have been asking me

My answers are exactly the same as o-ring's for every question. Although, having done a few 'no mask' diving exercises recently I am thinking about carrying one.