Beep beep going into decom :-( or :-)

[vicky]

You must read Rychard Pyle's article "confessions of a mortal diver". After you read it you'll know why I asked you to do that.
I think Pyle summarizes the whole issue like this (not exact words):
Here is a link to the article:

http://www.bishopmuseum.org/research/treks/palautz97/cmd.html

A fool is one who does things without awareness of the dangers involved.
An insane is someone who does things in spite of the dangers involved.

IMHO your first post (where you say that you got into 14 minutes ascent time) puts you into the "fool category". Get proper training and cross into the "insane category"- it is much better to be crazy rahter than fool! At least you'll know what you are doing...

 

[fins wake]

... reply I've been working on for the last half-hour, so here's the abbreviated version. Maybe it's for the best?

Falcon, you're misunderstanding most of us. Most of us are not flaming blackice, but giving him the advice he's looking for. I don't feel very hypocritical about that at all. (Hypocracy is actually not one of my vices, but I do have many others, mind ... )

As for your experiences in Coz, you're right in taking your computer and your training seriously. That is, unfortunately, not too common in the area. (Shame, because there's some good tropical diving there.)

However, first, your computer does seem a tad on the conservative side. I've got a reasonably conservative one myself (the Vyper) and I always consult my RDP (and occasionally other tables [DCIEM, BSAC, MN90, NST] too, for educational value) on fun dives and 40-60 feet square profiles shouldn't put you "dangerously close to decompression".

As an aside, you can - and should - always ascend a few feet when approaching the decompression limits on the dives you've outlined. This gives you nice, slow and safe ascents and great profiles. On tropical reef diving this is always possible, and good DM:s leading their little flock will dive this profile. Again, Coz has its fair share of bad DM:s ... (personally I will follow my own profile).

As for Genesis' comments, with all respect he's missed the point and is misunderstanding the audience he is advising. With one (notable) exception I agree with his comment that all dives are deco dives anyway. The exception of course being that most dives performed by leisure divers are not COMPULSORY decompression dives. This makes one heck of a difference and this is why Genesis - like so many techies on boards all over the world - misunderstands the target audience. Many people reading this board will NOT have redundancy in any sense of the word, they will NOT dive in experienced dive teams (or even with experienced buddies) and they will NOT yet have the TRAINING to use any possible redundancy in the correct and safe way.

Hence, if there is catastrophic gas (which is almost invariably air) loss or similar, they will bolt to the surface. If you do this in non-compulsory deco diving, i.e. when staying within NDL limits, you hopefully might avoid injury. If you do this in compulsory decompression diving, it's not a good day ...

Therefore, I strongly disagree with Genesis. For most divers out there, decompression is a big deal.

EDIT: One addition, I actually don't agree with Genesis that as an NDL diver all decompression is done during the surface interval. This is - in practice - the case only if one does a square profile and shoots to the surface at say, 18 m/s, omitting the safety stop on the way. I strongly advise against this type of dive practice and methodology even if strictly speaking, some tables allow for this to a certain extent. ALWAYS, slowly ascend if possible, try to do multi-level ascents e.g. if reef or wall diving and have a minimum 3-minute safety stop on all dives. EDIT OVER.

 

[Falcon99]

I really didn't think my post was going to generate so much discussion, but it is all wonderful. Thanks BigJet for the good words and encouragement. I should have put more emphasis that most of the frustration was coming from my newby status, trying to follow a set of rules put forth, receiving a completely different one out 'in the field' and getting chastized by it as a bonus. I was really hacked, but what do you do in a situation such as that? As ethics called, I professionally and properly let a few important people know (the DM and my partner in a nice way) not to be alarmed if I pointed at my computer and started my 30 fpm ascent. I wanted them to know I was trusting my computer, not the DM's or my partner's.

If someone got bent from a gross deviation, the fault would have been ultimately theirs anyway. As I understand the rules, it is your responsibility to be safe.

I'm probably at a disadvantage here because I was 'programmed' to crosscheck CONSTANTLY during the aircrew days and probably don't enjoy dives as much as the average joe. However, I knew exactly where my buddy was at all times, along with my depth, N2 sat, and air pressure. (It never leaves you , I just have to frikken be up on the SA!! )

I wasn't intending to flame anyone either, just vent a little on what I noticed as a disregard for rules set forth during the OW certification process. It frustrates me to see the general OW principles invalidated the moment you step off the boat. What was all the OW training for then?

One more thing, I didn't see you all flaming blackice. Maybe that was a poor choice of a word. For me, it didn't make sense to see the 'don't deco unless you are trained' come from the diving masses after seeing what I saw in Cozumel. The Coz experience gave the impression that variation from the tables is uncomfortably common. My partner had years of dives, and the DM was also very experienced. Why would they react in the manner described if such deviations are uncommon? No one else ever commented about busting the tables - and they had simple analog gauges, not computers. That also made me nervous and further supported the idea that this is fairly common.

Again, thanks for the great posts. This is definately a great message board!

Jim

 

[Genesis]

is that the "safety stop" is in fact a deco stop, as is your slow, normal ascent.

Blow off that ascent and play rocketship and you may find out that your "no deco" dive wasn't, and you just got nicely bent.

I completely agree that you MUST have the gas supply (and I did note that you must KNOW you have it, not THINK you have it - and that this implies redundancy) to be making dives that have a mandatory ceiling. But that requirement really extends to a lot of "no deco" diving as well, because there is, beyond 30' or so, really no such thing.

You can bend yourself quite nicely making a fast ascent from 60', and I don't think anyone here wants that experience.

 

[MikeFerrara]

Falcon99 once bubbled...

I wasn't intending to flame anyone either, just vent a little on what I noticed as a disregard for rules set forth during the OW certification process. It frustrates me to see the general OW principles invalidated the moment you step off the boat. What was all the OW training for then?

Good point. Many instructors and the text warn students not to dive beyond their training and experience as far as depth, overheads ect, yet they'll be peer presured by DM's and other divers to do just that their very first time out.

In cave training students are tought to recognize and carefuly concider "trust me dives" before doing them while they seem SOP in recreational resort diving.

IMO, there are few thing stranger than the fact that otherwise inteligent successful people will totally trust their safety to a $3/day DM in some third world country when they wouldn't normally trust their lawn care to them. Go figure.

 

[BigJetDriver]

Dr Deco once bubbled...
Dear Readers:

You have good advice from many of the responders. No, you will probably not get DCS if you extend the limit by a little. However, as is true with any limit, it indicates where the territory is becoming a hazard. Diving can have serious consequences, such as paralysis.

You never want to get into the habit of thinking, I avoided DCS once going over the limt, MAYBE I can do it again. Maybe those earlier times you were well hydrated, light on the physical activity, and so on. The next time, when those conditions are not met, you get hit.

Folks,

In the military and police lines of work, we have what are called "Rules of Engagement", and we work in and around those. I have reprinted Doc Deco's words because, as philosophical and practical guidance they cut right to the core of the issue.

As Rules of Engagement go, FinsWake, Genesis, and others have stated it correctly.

(1) All diving IS decompression diving, of SOME type.

(2) MOST recreational diving is done with reference to what are called No Decompression Limits but should be called "No Required Decompression Stop Limits" (with emphasis on the word "required").

(3) EVERY decompression algorithm, be it meter or chart, utilizes ASCENT RATE as part of the algorithm, AND if one is engaging in repetitive dives, SURFACE INTERVAL as well.

(4) The "Recommended Safety Stop" is actually a type of decompression stop, but its presence is not actually required by the algorithm. (It is not what is called a "Glass Ceiling".)

BEFORE ANYONE GETS TOO FIRED UP, SHOULD ONE DO A SAFETY STOP? YES, AND YES AGAIN, AND YES ALWAYS IF AT ALL POSSIBLE! I CANNOT BE ANY MORE EMPHATIC THAN THAT WITHOUT DESCENDING INTO MORE PUNGENT LANGUAGE!!!! (Reference Doc Deco's comments above.)

(5) When we go out to dive, we either plan NOT to have decompression requirements, or we plan to HAVE them. In the first case, (which takes in most of our recreational diving), any excursion from the plan which causes us to wind up with REQUIRED decompression stop time is considered an event requiring either cautionary or emergency procedures. (See any set of dive tables for directions on what to do if the "NDL" is exceeded.) If we PLAN to have decompression requirements, this is a different program altogether, requiring more training and equipment.

As Mr. Natural used to say: "Get the right tool for the job, kids!".....or as Doc Deco is fond of quoting: "An investment in knowledge always pays the best interest.---Benjamin Franklin" =-)

 

[fins wake]

... from BigJetDriver69. Newbie divers, print out the post, laminate it and hang it on the wall. This is what it's all about. It's well-written and useful and could easily be reprinted verbatim in an OW manual.

Well done! :yea:

 

[blackice]

vicky once bubbled...
You must read Rychard Pyle's article "confessions of a mortal diver". After you read it you'll know why I asked you to do that.
I think Pyle summarizes the whole issue like this (not exact words):
Here is a link to the article:

http://www.bishopmuseum.org/research/treks/palautz97/cmd.html

A fool is one who does things without awareness of the dangers involved.
An insane is someone who does things in spite of the dangers involved.

IMHO your first post (where you say that you got into 14 minutes ascent time) puts you into the "fool category". Get proper training and cross into the "insane category"- it is much better to be crazy rahter than fool! At least you'll know what you are doing...

Vicky, that sure is an interesting article, and it points out that getting bent is not fun and it really sux.

I have no plans to go into deco until I have the training. But have more desire now to get the training.

Cheers,
=-)

 

[GreatInca]

Good thing I havn't developed too much desire for wreck deving yet (too expensive to get to good sites). I mostly like the colorful fish and the seals and they don't like going below 40ft so I don't either. I am an efficieent air user too so I don't like the Nitrogen being my bottleneck - rather havee the air be the bottleneck. My puter pretty much gives unlimited bottomtime at 30ft or less. The depest ive been was 120ft but theres not much theree. Some isoloated fish some black coral, not many colors. But I've only had 11 post-certification dives also, so I'm not that all that experienced. BTW i started ascending from that deep dive when I had 3min of NC left gotta love that 'puter though. Come up to 30-40 ft and it gives you a whole 20 min to chill with the fishes and take pictures. One thing I notice is that when your ascening from a deep dive your body wants to breath faster (not hyperventilating more like a mild wind)? It lasts a short time. After 2-3 minutes it goes away. Is that the Nitrogen offgassing?

 

[Atticus]

Excellent post there BigJetDriver. In one post you've cleared up most of the misconceptions/arguments about NDL/Deco diving.

I was on the beach when a group of three divers came up and were a bit ... panicky ... It seems they had a reg free flow at 130' (at 6000' altitude) and bolted to the surface. They went on to O2 immediately and somehow managed not to get bent. Scary stuff. My point is that with doubles, etc. you have some good options when equipment fails, whereas with recreational gear you're kind of limited.

Falcon - your approach is exactly right. IMHO if you choose to consider technical diving training in the future your approach will continue to serve you well. Shame on anyone for suggesting that you not follow your dive planning aids (be they tables, wheel, computer, whatever). We have a rule that any diver for any reason may call any dive, without any hassle.

Genesis - you're right of course, but I have to agree that the perceived message may be a little confusing for newer divers

BlackIce - it sounds like you're on the right track, and I applaud your interest in further training.

Best Regards,
atticus