Its pretty easy to teach that lesson without taking the risk of heavily saturating oneself.
Here's how I approach it:
1. If using a GF driven computer (i.e. Shearwater etc), pre-plan a conservative NDL for the dive. Track that NDL and surface well within it. Set GF to something ludicrous (like 10/30) so that significant staged deco is reached very quickly. I use this method for running 'simulated staged deco' training dives with tech students, whilst also keeping dive parameters very conservative during the learning (and mistake making) phase of training.
2. Conduct a dive using an appropriate EANx mix, but leave the computer set for air. Plan the EANx NDL and dive within it. The computer tracks as per air, so you can enter lite deco safe in the knowledge you're well insulated from DCS risk. I use this to teach recreational divers how their computers will respond/display to emergency deco situations.
For recreational divers, my message is simple:
DCS risk is a grey area, not black and white. Modern decompression algorithms and no-stop limits keep divers reasonably safe from risk, even accounting for other predisposing factors.
As you approach no-stop limits, there is less insulation against those risks.. so one has to be much more mindful of contributory risk factors like ascent speeds, safety stops, proper hydration, exertion, thermal protection, body composition, cardio-vascular fitness and personal physiological issues.
Exceeding no-stop limits makes dives less forgiving. Smaller predisposing or dive management factors now have a more immediate and profound impact. The medical consequences of those factors occuring become more severe.
As those no-stop limits are further exceeded, the DCS risk changes from reasonable to unreasonable. From unlikely to likely. From non-damaging, to injurious, to potentially fatal.
Those risks cannot be eliminated, but they can be mitigated. Risk mitigation is possible through appropriate and specific training and equipment... all of which is readily available across the globe.
We are in agreement. As I said MANY times, you have a very positive contribution to a lot of posts in the forum. However, sometimes "general statements" are abusive for me. I totally agree with Patoux's quote:
"See, the problem with most of your statements, is that many of us read "train with me or you're gonna die" in it."
The idea to use computer with "crazy" GF is a good one. Having said this, very few non Tek divers have such a dive computor. So the idea to dive Nitrox on an Air computor is a great one - providing that you keep the REAL MOD in your head. This is by the way what I used to do with the well known old ALADIN pro that did not allow nitrox settings.
I don't recall seeing what you just quoted anywhere in this, or another, thread.
Who are you quoting exactly?!?
"Mortal sin" may not be the appropriate wording. Excuse my French . Devon Diver and KenGordon eluded to the "same thing". My experience is the same: Most of the PADI divers that I have seen consider diving beyond the NDL as a CLEAR NO- NO. The warnings that you have on some "recreational basic computors" also give you the impression that you are going to die or suffer if you enter into deco. The adverse result is that if a recreational diver enters into deco, he might freak out and then, really hurt himself. I have never seen this with experienced CMAS Divers.
I think that the old fashioned approach is actually the one taken by the big commercial agencies. By categorising deco diving as completely 'other' and having stuff like having to not dive for a period of time if a diver goes past NDL they have created a whole new category of pushing things. Having hard rules rather than having divers evaluate risk.
. I too have seen (and read about) so many people freaking out by going into deco. I think it is an important issue.
Depth: 95 ft, In Deco, 500 psi, No Buddy
The reason technical diving training exists is to mitigate those increased risks. It provides a significantly higher standard of dedicated training, along with a proven (accident analysis driven) equipment and techniques blueprint for preserving a high degree of safety and risk insulation. In short, it balances risk appropriately.
FYI, I do not consider myself a tek diver but I went throug IANTD Advanced Nitrox. I regularly dive with a 80% deco stage. So I understood the need for training. This is not the point.
You seem to imply that technical divers do minimise risks. I would love to see data on this - see later - . Yes I have seen diver suffer from ADD. The few people that I know that suffered from ADD to the point that they went to a recompression chamber ARE TEK Divers.
I am not so sure that the "average" tek diver makes safer deco than myself. They tend to use enriched gaz in order to shorten their deco time, while when I am using my deco with 80%, I switch on my enriched mix only on my main computor, but keep the deco time from my travel gas. So this gives me two deco runs: one safe and one emergency/bail out.
When it comes to data, I would be VERY interested to see mortality and ADD rates per dive for TEK/CMAS/PADI divers in order to see what is safer in the real world.
I would also love to see a comparison of ADD frequencies in 2 sets of people diving with the same GF: one group making long deco times with their travel gazes and another one making shorter deco times on enriched air.
I believe that without these data: any affirmation is "wishfull thinking".
Last edited: