NDL

[wreckchick]

Mike,

First of all I didn't know you had been ill and I wish you a speedy recovery.

MikeFerrara once bubbled...


I certainly would never try to make you do anything. Why don't you like it that we're talking about diving? There is a travel section on the board. They won't tire you with dry talk about decompression theory.[/i]

Did it occur to you that the reason I'm participating in this thread is that I am interested in decompression theory? What I'm not interested in is a bunch of hardcore technophobes telling me why my computer in the water is more dangerous in the water than their "diving by feel" methods.

If trading information and ideas is rushing people then yes many of us are guilty. What would you like to talk about?

I'm not sure why you feel like this whole thread has been a personal attack against you and/or your methods. You seem very defensive about some of the subjects that have come up here.

The condescending tone in your posts is what will turn off a new diver or a new member to the forum from all your ideas when I think we both know that you have a wealth of information to share with newer divers.

I take great offense that you seem to feel that I'm not up to the challenge of participating in this thread. Would you prefer I go to the travel section and book myself a little trip and ignore everything else on the board? Do you think that will make me a better diver and help me to learn decompression theory?

Maybe I should just go bounce around the reef and leave the important stuff to the experts. Let you all argue whether or not I should be using my computer. I eagerly await the memo telling me what I should do.

R

 

[Epinephelus]

biscuit7 once bubbled...
Maybe I should just go bounce around the reef and leave the important stuff to the experts. Let you all argue whether or not I should be using my computer. I eagerly await the memo telling me what I should do.

Well, you certainly shouldn't "take your ball and go home!" You have some good points worth considering.
Now, personally what I see here is an awful lot of arguing at cross purposes... "The grass is green!" "No, the sky is blue!"
At the bottom of everyone's point is "dive safe."
There is a safe "envelope" for diving that includes limits in depth, time, profiles, ascent rates, stops, temperature, current, hydration, planning, entry, exit, physical strength, endurance and fitness, light, visibility, marine life, weather, buoyancy, etc, etc, ad nauseum.
There are myriad tools to help us remain within that safe envelope, and a dive computer may be quite useful to some folks as one of 'em. To depend on a dive computer as the end-all and be-all for time, depth and profile definition is folly. To reject dive computers entirely is diving with an incomplete tool box.
E. itajara

 

[Epinephelus]

Anybody else notice that Uncle Pug dropped his little grenade and left?
E. itajara

 

[sheck33]

Epinephelus once bubbled...
Anybody else notice that Uncle Pug dropped his little grenade and left?
E. itajara

somehow i have the feeling that is what he wanted to do :mean: it worked

 

[MikeFerrara]

biscuit7 once bubbled...
Mike,

First of all I didn't know you had been ill and I wish you a speedy recovery.



Did it occur to you that the reason I'm participating in this thread is that I am interested in decompression theory? What I'm not interested in is a bunch of hardcore technophobes telling me why my computer in the water is more dangerous in the water than their "diving by feel" methods.



I'm not sure why you feel like this whole thread has been a personal attack against you and/or your methods. You seem very defensive about some of the subjects that have come up here.

The condescending tone in your posts is what will turn off a new diver or a new member to the forum from all your ideas when I think we both know that you have a wealth of information to share with newer divers.

I take great offense that you seem to feel that I'm not up to the challenge of participating in this thread. Would you prefer I go to the travel section and book myself a little trip and ignore everything else on the board? Do you think that will make me a better diver and help me to learn decompression theory?

Maybe I should just go bounce around the reef and leave the important stuff to the experts. Let you all argue whether or not I should be using my computer. I eagerly await the memo telling me what I should do.

R

I haven't been ill but thanks anyway.

I didn't take anything as a personal attack. I did get the impression that some of you were suggesting that somehow by talking about the technical aspects of diving that we were rushing/encouraging divers to take up technical diving. From several posts I got the impression that some of you objected to the subject in general or the idea that the average diver should be encouraged to learn something about decompression. Maybe I misunderstood but that was the impression I got from roturners first post and yours that followed. The condescending tone was in response to comments to the effect that most divers don't care. I figure, ok, if they don't care then they don't have to listen. I never said divers shouldn't use computers. I did say though that I often see them used in a mannor that I think is incorrect.

 

[wreckchick]

The point that I think we were both trying make is that a detailed knowledge of the history of decompression theory isn't important to most divers. They are perfectly willing to accept the NDL set by the tables and/or the computer and abide by them as a way of controlling the risk of a DCS hit. It is unwise, IMO, to have no respect for the tables and to dive a plan (or nonplan) that doesn't, at some level, account for all the research that has already been done on our behalf by people with the resources and experience to make strong recommendations about reasonable limits.

Recreational divers use the RDP or computer to give them these limits, technical divers use hand calculations and/or sophisticated computer software as aids, and some people use the divemaster off the boat that had the cheapest package. Some of these methods are more wise than others but they all encompass some way of minimizing risk in the opinion of the diver on that particular day.

This thread was started because of a diver pushing an NDL based on a computer without ample air supply. There was error on both counts. The reason I spoke about rushing a new diver into more technical training is because it is easy to believe that more advanced training makes a diver more competent in more technical diving. I think that recent events have proven otherwise. I think it's possible that diver, and who knows how many others here and elsewhere, felt the pressure to take a class and then thought that it adequately prepared him for more advanced environments.

I have aspirations of doing more technical diving in the future, but I don't think the false sense of security gained by taking advanced classes does me any good in the long run. I'd much rather do more recreational diving, wait for inevitable glitches and learn to handle them at a recreational level, then when I feel like nothing can spook me at this level move on to the next.

I read these forums to gain knowledge from other people's experiences, learn how to prevent some of the more common occurences, have a basis for decision making for some of the other stuff, and to make myself a safer diver for my own well-being, that of my buddy, and anyone else in the water with me that day.

I could ramble on, but I won't

R

 

[MikeFerrara]

The DAN report...

I haven't printed out this years report yet cause it takes so long to down load it. But...the thing that always hits me like a brick is the percentage of injured diveres on which buoyancy control problems are reported. I have posted about these reports before. They can't really be used for any probability calculations because the data is incomplete. However, I think you can use them to draw a picture of the divers who are getting hurt. Overwelmingly they seem to be divers with poor skills, little recent experience and not much training. This could be because a large percentage of divers fit that discription (which would be bad) and/or because having poor skills and little recent experience can get you hurt.

I use the report to support my position to my students that having good solid basic skills is the best thing you can do in the interest of your safety. Since good solid basic skills also makes diving more enjoyable I just don't see the downside. Yet the argument is always the same... The injury rate is so small that it's ok and diving is safe enough as is, casual divers don't want to be pros or put in the work ect, ect.

IMO, understanding enough about decompression to know what you want your profile to look like is just another link in the chain. Some one said earlier that riding the computer represented a point on the risk curve and that if a person decided that point was acceptable that it was a valid choice. I agree. My question is how many knowingly make that choice? I think that's the real subject of this thread, understanding the significance of the NDL and what other aspects of the profile are relevant. Personally I would rather spend some time shallow (deco) before getting out of the water than stturate myself to the M-value of the leading compartment and get back on the boat. It's easy to do if you have enough gas for the dive. However if you want to do a 100 ft dive on a single 80 you either don't have much time at depth or you just get out of the water loaded. It can work if your working your way up along a reef and spend little time at your max depth. But if your on a wreck (square profile) you either don't get much of a dive or you get out loaded (see CJ's thread).

Who is rushing divers toward tech? Someone like me who says a single level 100 ft dive is best done with doubles and planned decompression or some DM, agency or who ever who leads you to believe that your properly equiped for the dive with your computer, NDL and single al 80?

 

[wreckchick]

is rushing divers toward tech? Someone like me who says a single level 100 ft dive is best done with doubles and planned decompression or some DM, agency or who ever who leads you to believe that your properly equiped for the dive with your computer, NDL and single al 80?

I think both of you are wrong. Not only is a mistake to take a diver to a deep(ish) wreck with a single AL80 and a computer, but it's also a mistake to tell a newer diver that getting the deco training and learning to dive with doubles makes them safe for extended periods of time at depth. That diver is just as at risk if they have a problem at 100' within the NDL and make a direct ascent or has to do emergency deco as the new tech diver with doubles and a plan they blow off because they freaked out when something unforeseen happened.

A diver can't possibly know how they will react to an emergency situation or just a mildly harrowing one until it has happened to them. The only way to know how you, as an individual, will react is to go through it and. For myself, if and when something happens, I would rather I was shallower with plenty of air in my tank and enough NDL time to work the problem out. That is my level of risk assumption.

R

P.S. My built in level of conservatism means I get all wobbly if I see my NDL time approaching 10 minutes.

 

[O-ring]

Doubles can be dangerous because gas supply is eliminated as a limiting factor on deeper recreational dives. It becomes VERY easy to overstay an NDL when diving doubles..

 

[TCDiver1]

O-ring once bubbled...
It becomes VERY easy to overstay an NDL when diving doubles..

what i would say is, anyone who would consider overstaying a NDL with twins, would consider it, if possible, with a single.

Its the wrong mentality all togeather. Chances are this person will never take the theory seriously .... no matter how hard someone tries to teach it.

To extend that thought one step further ... anyone who is serious enough to learn the basics of decomp. theory, IMO, will be just fine using tables or computers. If they are dumb enough to consider diving over NDL's, on a regular basis, it won't matter what they use to plan their dives.