Very clever marketing :-)

[Reg Braithwaite]

To summarize:

• I should go cheap and try to buy a computer with gauge mode used, or just go for a UWATEC gauge.
• Models, models, models. It's possible that what one model considers conservative, another model considers bent.
• Deco for Divers rocks. I haven't read Weinke or Buhlmann yet, but after spending an hour with D4D, I can tell you it has far surpassed anything else I have read about decompression, including "Getting Clear on the Basics."
• Putting the last two points together, the book opens up by saying that "Nobody knows." He says outright that almost every sentance of the book could be prefaced with "Curent thinking is..." and "Some experts believe that..." He also says that empirical evidence is inconclusive. Studies have small samples, and contradictory results can often be found. So if one paper says "It works like this, which is proved with the following tests," another paper can be found to state the opposite with tests to prove that as well.
• Lynne is, as usual, a voice of reason.

 

[wreckchick]

So, back to a previous semi-hijack with this article...

I understand the author did the most conservative thing possible when he sat himself for 24 hours due to computer failure and then planned to resume diving on the tables. The logic for me breaks down when if he was using recreational tables for the entire trip, he would have been clean on that first dive on day two and totally allowed to dive.

Am I missing something?

Rachel

 

[RTodd]

I understand the author did the most conservative thing possible when he sat himself for 24 hours due to computer failure and then planned to resume diving on the tables. The logic for me breaks down when if he was using recreational tables for the entire trip, he would have been clean on that first dive on day two and totally allowed to dive.

Am I missing something?

Rachel

I didn't get past the first paragraph because the article is totally inapplicable to DIR diving. We don't use dive computres to determine our ascent profiles. Period.

As an aside, you are basically completely clean of residual nitrogen after 6 hours if you are doing "NDL" dives with proper (important distinction) ascents. The 24 hour rule is just another piece of the super conservatism dive computer manufactuers use to cover themselves from potential liability.

 

[RTodd]

Well, the computer is likely less conservative than the tables, in that it allows for multi-level profiles and what-not. So, it's entirely possible that had he dived tables on day 1, he would have been clean to dive tables on dive 1 of say 2, as you say. But since he dived his computer on day 1, he might be more loaded with nitrogen than he would have been had he dived with tables on day 1.

Therefore, he could be outside of the assumptions used to craft the tables. Is he really unsafe? Probably not. But as a story, it has been helpful to me in thinking about DIR.

Okay, for the "special" kids in the room that can't read the first sticky.

Just a few guidelines...
1) No trolling! This is not the place for agency bashing! This is especially not a place for bashing DIR divers. Refer to Notice: the DIR forum is a No Trolling Zone for any questions about what constitutes a troll.
2) This forum is for a free exchange of ideas concerning DIR, but it is NOT intended to limit any mention of DIR to only this forum. There are many things pertaining to DIR that will be discussed in other forums as well.
3) All the rules of the board still apply here. You don't get to harrass or call people names. Civility should rule.
4) Most of all, have fun and learn something at the same time. Read our Mission statement and TOS for clarification.
5) This forum is NOT intended to replace or reduce the need for training with a qualified instructor. You might get more out of this forum if you have at least completed a DIR-f course.
6) The answers in this forum are member's best attempts to answer questions within, and according the DIR diving philosophy. If you wish to give a non-DIR answer, please do not post it in this forum. If you do not wish your question to be limited to DIR answer, please ask it in another applicable forum.

So, give the DIR answer or don't post here. If you have questions about DIR, even if a bit off the mark, they get answered here. Frankly, your initial question was quite a bit off the mark, but that is fine since it appeared to be a genuine question. Discussing how to use a computer is shooting in a completely wrong direction though. This forum is most useful to those new to DIR. Not trying to change that. However, there have been a few of you lately that need to talk a great deal less and listen a whole lot more if you actually want to learn this stuff.

 

[Reg Braithwaite]

If you are spending your hard earned cash on diving and not the gear, PM me and I will mail you an extra uwatec BT I have in my dive gear and you can either mail it back to me or give it to Dan at your Fundamentals class. Either way, no biggie. Let your wife use your Gecko and dive the bottom timer.

This is exactly what I have decided to do. The Nitek Duo does seem like a better Bottom Timer in some abstract sense (larger display, yadda yadda yadda), but after sleeping on it I like the idea of being truly minimalist. A bottom timer that is only a bottom timer just seems like The Right Thing To Do for me.

I know the subject of BTs is old, old, old news for you folks, so thank you for indulging my questions.

 

[The Chairman]

Thread closed for cleanup. Please be patient as I deal with this a bit later today.

 

[The Chairman]

So, give the DIR answer or don't post here. If you have questions about DIR, even if a bit off the mark, they get answered here.

To add to this fine insight, let me add that this is NOT the place to debate the philosophical underpinnings of DIR or what you might see as some sort of disconnect between this and their actual practices. This is for people to ASK how and why and for those who are TRULY DIR proponents to answer to the best of their ability. We have enough of them here on ScubaBoard for those of us who THINK we understand DIR issues to simply SHUT UP as we let them tell us about DIR. That includes ME, and is why I don't post in here.

Now please, the pool is again open. We don't need to rehash the train wreck here in this forum. If you wish to discuss it further, please go to Site Support and start a thread in there. I am in the Keys teaching a very non-DIR class on Scuba and it will be a LONG while before I can come back here and check in to see how things are progressing. Please use the

button as you see fit while I am gone. I now return you to your regularly scheduled discussion.

 

[lamont]

So, back to a previous semi-hijack with this article...

I understand the author did the most conservative thing possible when he sat himself for 24 hours due to computer failure and then planned to resume diving on the tables. The logic for me breaks down when if he was using recreational tables for the entire trip, he would have been clean on that first dive on day two and totally allowed to dive.

Am I missing something?

That guy fundamentally doesn't understand decompression at all.

Keeps him safe to just not dive, not think about it. And if he did dive, he might spend the whole dive with fears about getting bent buzzing around his head, which would make him less safe of a diver. So, take option #1 and don't dive.

However, even with a minimum amount of understanding of decompression, he could have used tables and assumed a maximal compartment loading (W to Z loading) and take it from there by plugging in his surface interval. Even with the differences between tables and computers you can assume this and be fine -- but clearly the guy in question wasn't comfortable working through that logic and doesn't have enough understanding of decompression to confidently think that through. So not diving is the best option, just based on mental state.

And like RTodd said from a DIR perspective you're going to be clean after 6 hours -- but that assumes adequate deco on the last dive and adequate deco on the next dive, even for a recreational dive. Which is why you can't take bits and pieces of DIR.

(and what were all you guys doing at 7am in the morning (PST)? sheesh... i don't wake up that early...)

 

[wreckchick]

That guy fundamentally doesn't understand decompression at all.

Keeps him safe to just not dive, not think about it. And if he did dive, he might spend the whole dive with fears about getting bent buzzing around his head, which would make him less safe of a diver. So, take option #1 and don't dive.

However, even with a minimum amount of understanding of decompression, he could have used tables and assumed a maximal compartment loading (W to Z loading) and take it from there by plugging in his surface interval. Even with the differences between tables and computers you can assume this and be fine -- but clearly the guy in question wasn't comfortable working through that logic and doesn't have enough understanding of decompression to confidently think that through. So not diving is the best option, just based on mental state.

And like RTodd said from a DIR perspective you're going to be clean after 6 hours -- but that assumes adequate deco on the last dive and adequate deco on the next dive, even for a recreational dive. Which is why you can't take bits and pieces of DIR.

(and what were all you guys doing at 7am in the morning (PST)? sheesh... i don't wake up that early...)

and just to point a finer point on it, the PADI RDP has you clean after 6 hours as well and unless he REALLY screwed up the day before, in which case he shouldn't be diving anyway, I don't even think he would need to drop into any pressure group on the tables and just start that day with the recreational tables and continue on from there. If it was a second dive, I can see dropping out for the rest of the day and starting clean in the morning but to sit for a full 24 hours over something that really presents no increased risk that I can possibly fathom seems a bit of an overreaction from any standpoint.

Well, I've managed to take this completely OT... Thanks for putting up with me!

R

 

[RTodd]

(and what were all you guys doing at 7am in the morning (PST)? sheesh... i don't wake up that early...)

An infidel snuck in while you were out so we stoned them. Oh, and the guard just told the inmates he was going to be gone for a few days so you may want to don some riot gear.