Another Tables vs. Computers Thread

[Soggy]

GI3 has been known to pull tables out of his butt. So what? You won't catch me following tables built on a gut feeling. That turns a SWAG (Scientific Wild Arse Guess) into a DWAG (Delusional Wild Arsed Guess)! The former is bad enough!

Just because you don't know how to do it, doesn't make everyone else wrong, Pete. What works, works and if this didn't work, me and many of the other divers on this board would already be bent or dead. What's amazing is that those that don't understand how to do this argue and argue and argue until they are blue in the face, but the fact is that when I put my profiles next to one from vplanner, you would probably have trouble telling which one came out of my arse and which one came out of vplanner.

Just because you think I'm doing it for some egotistical or macho (or whatever nonsense you are believing at this moment about me) doesn't make it true. Al Gore believed in manbearpig, but that doesn't mean manbearpig exists.

I don't dive the profiles I do because of pride, I dive them because they work and are more flexible than the alternative.

 

[limeyx]

all i can say is that i am not nearly experienced enough to engage in that
type of diving, and may never be (i don't have a mathematical mind)

whereas i feel very comfortable ("close enough to fine") with deco software
and a computer.

but, you know, as i continue to dive, i'll start nosing in that direction and hey,
maybe i'll be able to "get it" and feel safe using it. i certianly would not
try it at this stage in my diving.

Indeed, it takes some getting used to, which is why
1) I am extremely reluctant to write any of the details in a public forum because you cannot "just start using it"
2) It's best to start with it in the recreational range as soon as you are comfortable with it even if it seems like overkill because then it is much easier to adapt to the more complex diving. The recreational case is really a special case of the Tech1(150foot) dives which is also a subset of Tech2 (over 200 feet) -- not that I am anywhere close to being able to do a 200 foot dive.

I wouldnt encourage anyone to "just start doing it" -- the best place is to start with a class that teaches/introduces the skills needed to prepare for going that route.

 

[TheRedHead]

So as one poster pointed out, you could relay solely on your computer, and if it fails, end your dive and stay out of the water for 24 hours (longer if it takes longer to get it repaired/replaced). OR... you can run your numbers with tables, switch to a watch/depth gage and continue your expensive dive vacation.

Pfffft. When my computer died in Bonaire, I simply ended the dive and went to the dive shop and rented another computer. And yes, I know how to use tables. I dive with a copy of the US Navy air deco tables.

 

[limeyx]

Oh the irony! Is it safe or not?

Honestly? I believe so or I would not be diving it.
However, I am not a world-recognized expert in deco theory so my opinion is worth what someone paid for it.

It's based on deco diving which is a very small sample size.

However, if as Soggy says, you compare a profile to one generated by deco software, you will often find that it's if anything more conservative. But you might also find the ascent shape is a bit different than some models.

Couple that with the GUE conservatism on gas choices (low PPO2, treating O2 as narcotic, high He content) and I think you have even more conservatism. (OK, i know there are a lot of people who disagree with GUE's stance on Helium -- and the deco is actually planned assuming no He in the mix basically).

I know I can do 2 150 foot dives with a 90 min surface interval following this method and feel like I haven't been diving.

Does that mean I wont get bent this weekend? Of course not, but neither does following a deco table or a computer. I could also get bent at 60 feet following a computer.

Sadly, deco is not an exact science. If it were, then I'd be first in line for whatever tool I needed to guarantee I wouldn't get bent.

But until that happens, I think this is a good method *if* you have the training, *and* you are willing to practice practice practice doing it and your basic skills so you can make it work. Some people have no problem taking the class but then dont want to put in the time in the water to cement the skills in.


A lot of people looked at me very oddly when I spent essentially the first 4 months of this year in 20-60 feet of water training for a class that would "only" qualify me to dive to 150 or 160 feet. "I can easily go to 250 feet with class XX" they said, and I didn't need to spend all that time doing those things. But I think it's the best time and money I ever spent on my diving, and the same thing goes for the earlier classes I took that people scoffed at.

 

[The Chairman]

Now... what has ALL that to do with the OP?

Ignoring issues of reliability, just considering understanding of decompression, why do so many people repeatedly say that learning to use the deco tables in OW is preferable to learning to use a computer?

Deco is not OW. Just in case that was also in question. Again, it smacks of ego, but I have been known to be wrong (unlike some).

 

[limeyx]

Now... what has ALL that to do with the OP?Deco is not OW. Just in case that was also in question. Again, it smacks of ego, but I have been known to be wrong (unlike some).

well,

1) A deco dive can be "Open Water" just not recreational OW (smartass comment I know)
2) if you know you might want to do more advanced diving, it makes sense (to me) to start off learning the techniques that will be applicable (in expanded forms) later on. Why learn two different ways?
3) there is a school of thought that says that every dive is a "Deco" dive. The ascent profiles I use for a rec OW dive follow the same rules as a more complex dive, just that since the procedure "collapses" down quite a lot for a simpler profile -- but still different than ascend to 15 feet and wait 3-5 minutes.

 

[The Chairman]

1) A deco dive can be "Open Water" just not recreational OW (smartass comment I know)

No, whether it's a "depth cieling" or a real one, this a deco dive is NOT an OW dive.

2) if you know you might want to do more advanced diving, it makes sense (to me) to start off learning the techniques that will be applicable (in expanded forms) later on. Why learn two different ways?

They really have no idea. PUSHING them in this direction before they even get wet is unconscionable.

3) there is a school of thought that says that every dive is a "Deco" dive. The ascent profiles I use for a rec OW dive follow the same rules as a more complex dive, just that since the procedure "collapses" down quite a lot for a simpler profile -- but still different than ascend to 15 feet and wait 3-5 minutes.

The difference is between a "precautionary" or safety stop and an obligated one. OW students have NO BUSINESS over complicating the way they dive with additional theories that have no bearing on what they are trying to accomplish. I guess I could demand that my OW students handle a reel and carry three lights as well.

 

[Blackwood]

3) there is a school of thought that says that every dive is a "Deco" dive.

That thought should be in every school. If the gas you are breathing decreases pressure, decompression is involved.

Recreational tables are and should always be thought of as decompression tables (even though when used properly they don't obligate "decompression stops").

 

[Soggy]

First, see that horse you are on? Get off of it, please and get off this ego BS you are tossing about just because I have an opposing (and strongly supported viewpoint). Unless you can justify your statements, they are nothing but backhanded personal attacks and I thought above the owner of this board. Get a little perspective...

Next, I posted this a couple pages ago explaining how this relates to recreational diving.

It is also much more flexible as it can be applied from OW 60 ft reef dives all the way to expedition level trimix dives. This is the law of primacy. Learn it from the beginning, it becomes 2nd nature, and you can build on this foundation.

Yes, I know I was referring to technical diving here, but can't you see how, if it works in a technical diving scenario, it would work in recreational diving which is much less complicated?

Now... what has ALL that to do with the OP?Deco is not OW. Just in case that was also in question. Again, it smacks of ego, but I have been known to be wrong (unlike some).

 

[Soggy]

I guess I could demand that my OW students handle a reel and carry three lights as well.

Well, if they are doing a night dive, at least 2 lights is definitely a good idea, probably three and I would suggest that reel skills are perfectly suited for an advanced open water class.