Going Deeper than 130'

[explorer08]

By definition, "technical" is a dive that either exceeds recommended recreational depth limits or exceeds no decompression limits.

The reference to physics implies what doing a dive beyond those limits does to your body. That isn't dependent on where you dive, or who trained you ...

... Bob (Grateful Diver)

I agree with your second paragraph, but that is not an answer to my question.
And your first paragraph is no answer as well. It is simply a quote of the definition.

With regards to that definition I refer to my answer I gave at 11:47PM to PfcAJ.

 

[MXGratefulDiver]

I agree with your second paragraph, but that is not an answer to my question.
And your first paragraph is no answer as well. It is simply a quote of the definition.

With regards to that definition I refer to my answer I gave at 11:47PM to PfcAJ.

The comment you questioned was an attempt at sarcasm ... apparently not a very good one ...

... Bob (Grateful Diver)

 

[hg frogman]

Once you have a decompression obligation, you no longer have access to the surface in case of a problem, at least not without a distinct risk of injury. Problems have to be solved where you are. Sounds technical to me.

The PADI recreational dive table requires a mandatory stop (3' at 15 feet) for a bunch of recreational air dives, e.g. 20' at 30 meters/100 feet, or 51' at 18 meters/60 feet. A mandatory stop is by definition a decompression obligation (i.e. a deco stop). So, following what you say, these recreational dives are in fact technical dives .

Same can be said of "Recreational Triox" which necessitates some deco stops.

As explorer08 very politely said, there is a broad grey zone between what is called "recreational" in some countries, and what all people around the world (French included) consider as "technical". And there is a broad grey zone between dives almost certainly allowing immediate access to the surface, and dives forbidding it (that depends a lot upon the diver, e.g. an old overweight smoking dehydrated diver vs a young Navy (or DIR ) non-smoking athlete perfectly hydrated). Don't forget that the NDL used to be around 30' at 30 meters/100 feet on air with Navy tables from the sixties.

Mild deco dives (a few minutes of deco on backgas) are generally not considered as technical dives in Europe. Many European divers receive the training and knowledge necessary for this kind of diving during the CMAS ** course, immediately after entry-level. And "recreational" is an unusual word in Europe. Personally I find that "mild deco" is more meaningful.

PS: if I was the OP I would follow Marc Blackwood's advice (second post of this thread). And given the context, I would consider 160 feet in a cold lake with low visibility as a challenging, technical dive with a high chance of narcosis, and would search for adequate training. And my training and my diving would go step by step, progressively deeper, without rushing (and the same for my buddy, who would need to be someone I can really trust underwater; it's a matter of team building and training, not only of OP's individual training).

 

[explorer08]

By the way, it contains some irony that the TO chose exactly the right forum for his question.

"Advanced Scuba Discussions
Have a Scuba question that's beyond a 'basic' one but not really 'technical?' Get it answered here."

 

[Spazzy]

Buckaltc,

HG Frogman is absolutely right - 160 feet in a cold lake with low visibility is a technical dive requiring training, progressive acquisition of experience, proper planning, the right equipment and a solid buddy/team you are familiar with. Approach this exercise with rigor and you will be rewarded with a new skill set and hopefully some great new dive companions.

Splitting hairs around what is and isn't technical these days is irrelevant to your post. So please don't be distracted by that discussion and seek out a good instructor/training organization.

 

[DevonDiver]

I don't think that viz and water temperature have any bearing on whether a dive is 'technical' or not, by definition. That doesn't mean that technical preparation (training and equipment) wouldn't be extremely relevant for the safe conduct of the dive.

I spent my initial years as a diver using BSAC '88 tables... which clearly allowed 'mild' decompression (single gas) for dives below 130ft. Those were often bad viz, high current, drysuit wreck dives around the UK coastline.

At the time, I didn't count these as 'technical' because they could be achieved with a single cylinder and no redundancy. My views have subsequently change and I now believe that any 'ceiling' dive should, at least, be done with a sufficiently sized redundant air source (I would use doubles). That covers the equipment issue... but not the training to use it.

The need to define 'technical' diving is important - as it gives a clear indication whether a diver should seek 'technical' training and equipment for a dive, or whether their previously gained 'recreational' diving skills and kit configuration are sufficient, at a given level of experience.

For any deco or overhead environment situation, then recreational diving skills and equipment would not provide a diver with enough contingency and flexibility to deal with problems that could arise. This is a grey area, however, as 'easy' dives in those environments ('mild' deco, or shallow wreck penetration) could be conducted with low possibility of incident. At this level of diving, the higher risk compared to an open water, no-deco, no-ceiling dive should lead the diver to undertake a risk assessment that reflects the dangers. Whether they should choose to apply a 'technical diving' solution...or a stringent/advanced recreational diving solution... is still debatable.

However, when conducting a risk assessment it is important to differentiate between the levels of unmoderated and moderated risk. Technical deco/overhead diving attempts to moderate risk to an acceptable level. Opting for a 'recreational' diving solution is an acceptance of unmoderated risk. That is a personal decision.

My personal feeling is that a technical diving solution is preferable. The ease of access to technical dive training and equipment has increased dramatically in the past decade. I feel it is always best to effectively moderate risks - no matter how big those risks are.

 

[Kevrumbo]

I have some questions about going deeper than 130'. I really have no desire to get into advanced tech diving for it's own sake, but I do want to get to around 160' or so. I live in Michigan and there are some things in Lake Huron that I want to see one day. I am a PADI Divemaster and I work mostly with Scout groups. I did this because I felt it was a great way to dive a lot and keep the costs down but I'm not a Divemaster for a living. I'd like to learn some more and do more wreck diving and to that end I'd like some advice on which way to go. I want to keep costs down of course, but I won't cut corners on safety. I'm a little turned off on DIR right now but I could be convinced--not a slam on DIR just what I read--I don't know enough to have a real opinion.

What is the minimum/recomended level of training and equipment needed to get to 160'? And where would you go for training? I know the question is a little lame, I'm not a minimum prep guy. The goal of my post right now is only to get enough information so I can start asking better questions.

Simply put. . .

At 160'/48m for 10 minutes, I would have consumed 870psi (or 58bar) from a set of double AL80's (same as twin 11 litre tanks). Therefore, if I was on only a single AL80, I would be consuming 1740psi (or 116bar) in those 10 minutes. My cold water SAC rate is 22L/min or 0.75cf/min.

Based on the quick gas calculation above, I definitely would not consider doing this even as a bounce dive on a single AL80 tank!

Now with additional important factors such as narcosis, decompression obligations, overhead wreck diving techniques etc. --you need to matriculate through a technical training process in order to do this dive safely and sanely. . .

All of us involved would tend to agree that Technical Diving has produced some of the most outstanding diving experiences of our lives. To safely share those experiences with divers who are interested, informed and ready is one of our primary goals. Technical Diving carries with it potentially higher risk than recreational diving (due to overhead environments, decompression obligations, physical and psychological demands etc.) and consequences of mistakes can be more severe. Higher risk however, does not mean dangerous. Much of the management of added risk comes from the divers themselves - from having the right attitude and sound skills and knowledge appropriate for the level of dive. . .
Diving Training Philosophy @ Tech Asia Divers Institute

 

[hg frogman]

I don't think that viz and water temperature have any bearing on whether a dive is 'technical' or not, by definition.

Whether they should choose to apply a 'technical diving' solution...or a stringent/advanced recreational diving solution... is still debatable.

There is a grey zone between technical and not really technical/mild deco dives. In my opinion, many dives between 130 and 170 feet are in this grey zone. And yes, visibility and water temperature are important factors for deciding if a 'technical diving' solution or a 'stringent/advanced recreational diving solution' will be chosen, partly because these factors heavily impact narcosis.

In warm, clear, tropical waters, when everything is all right, I don't mind sometimes going at 160 feet with an AL80 of air, and my wife as my buddy (we are both trained/certified for deco diving & procedures at that depth). But I dive also in cold Alpine lakes. For the dives the OP is talking about, if I was him I would go all the way to Normoxic Trimix certification before doing these dives. And dive only with trustable buddies. And we'd go step by step.

PS : Choosing the right amount of gas for the dive is up to the team, according to their SACs and proper gas planning. Not everybody has the same SAC.

 

[DevonDiver]

If narcosis was the only primary factor in determining between technical and non-technical dives, then I would agree with you completely. I suppose cold water can increase risk of free-flow... a major concern on a single tank with a deco ceiling..... but otherwise, there are plenty of factors which should dictate a technical approach to a dive.

I believe that viz and temperature only pre-dispose a diver to narcosis through psychological means. It is underlying stress - that becomes apparant with smaller amounts of narcosis. If that is true, then it would mean the conditions were beyond the diver - not the depth. IMHO, the answer to this is to get comfortable and acclimatized to the conditions, rather than substituting a gas answer.

 

[hg frogman]

I believe that viz and temperature only pre-dispose a diver to narcosis through psychological means. It is underlying stress - that becomes apparent with smaller amounts of narcosis. If that is true, then it would mean the conditions were beyond the diver - not the depth. IMHO, the answer to this is to get comfortable and acclimatized to the conditions, rather than substituting a gas answer.

That makes sense. For sure, stress is a major factor behind narcosis.

Poor visibility increases stress, but may also increase narcosis by perturbing body's equilibrium (like when you are skiing in bad weather and it's all white). I don't know. Apart from the stress, bad viz has its own hazards, notably on a wreck: disorientation, unnoticed overhead, unnoticed fishing nets or lines, higher risk of entanglement, buddies' separation, etc. Bad viz is a very serious enemy.

Sure Trimix is not the only remedy: a warm-clear-water-only Trimix diver shall get used to cold water and bad visibility before any deep diving in cold lakes.

And an Advanced Wreck training won't hurt if the OP doesn't carefully stay outside of the wreck, as he should if he has no training in wrecks' penetration.