The 50 hours magic boundary

Hi Josh

Thank you for your post.

I am quite happy to accumulate the hours since, as you said, they are not that hard to accumulate. I was just interested in how and why the 50 hours have become an acceptable norm just as, for example, the 40m Sport diving limit. (We know the effect of Narcosis so here I am happy). Kevin's post was very interesting as he went into the history of the 50 Hr rule.

Good point... and a good post by Kevin, indeed.
 
I am not a Revo diver so I could be wrong. But I do not believe that the manufacturer is recommending that you use the RMS system to extend beyond recommended hours per scrubber change.


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Well we were taught to use the scrubber monitor to determine when to cycle, not the recommended hours per scrubber cycle time. This is the major benefit of the rms. It calculates the remaining scrubber time and adjusts it continually while diving to allow you to use all the scrubber material. Remember this is actually only the 1st scrubber being used up, keeping the second as a backup for when the 1st breaks through. Paul actually taught us in conjunction with another instructor. Non rms revo must use recommended cycle times. RMS revo scrubber cycle based on actual usage of material.

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I think you will find very few experienced CCR divers or CCR instructors who feel that rushing to the next level of training without putting in sufficient hours gaining valuable experience is a good idea. Virtually every instructor I know recommends taking it slowly and methodically. Dives, cycles, hours, however you want to put it, meaningful experience is gained over time and can not be rushed IMHO.

Baby steps and repetition builds muscle memory and confidence. It only takes one mistake to ruin your whole day (as in kill you!), so why not slow down and enjoy the ride? Isn't what this is all about? Its not a race and it certainly requires a bit of patience. Better to understand that going in and accept the fact that it will take time to gain mastery.
 
Personally, I think the difference between mod 1 and mod 2 is well, (insert some inappropriate metaphor here)..

Diving trimix 160ft or 200ft is a difference in gas planning, and if it takes you 50 hours and another class to figure that out, perhaps you shouldn't be diving a CCR.

I dont know where or how those levels got set, but they dont seem very realistic.

So while I agree on 50 hours minimum between classes, the class itself needs to actually require 50 hours to get there.
 
I used to teach for an agency where the community was small enough to have an individual progression route set out for each diver. I could say do 25 dives before your next class - or do 50 dives before your next class and the following instructor would see this and ask for confirmation.

When my buddy and I went to RB our "path" was 15 dives at rec level, 15 in the mid normoxic range then 15 in the deeper range. Only then were we considered ready to do what we had bought the units for - which was to go deeper. We sort of followed the same self imposed route in caves. took us two seasons to get back to where we were before and start doing more challenging dives.

When we moved over to the JJs we took it steady but not quite to the same degree as before. We self imposed limits on our dives which we would have exceeded three months earlier on a familiar unit. Again, it took about a year to be back.

I am another that does not believe in 'hours'. I know too many who stay in the water a bit longer to build up their hours. This is not building experience.
 
I also know of one person who has two Mk VI batteries. He has given a buddy of his (ex 'Mod 1' student of theirs) to log hours on 'his behalf' so that he can accelerate his progression to becoming a Mk VI trimix instructor when the opportunity arises.

I have spoken to the Trg Directors of the Agencies who may be impacted about this practice and they say they will be able to trap it.

Unfortunately there is nothing the 'system' can do about this especially if units do not have a logging device, other than trying to instil the sorts of attitudes above, where there is recognition that accelerating progression is not necessarily the best course of action, especially if you are going to be an instructor.

This 'experience issue' isn't just limited to sporting activities, these are from 'The Killing Zone' (The Killing Zone, Second Edition: How & Why Pilots Die, Second Edition: Paul Craig: 9780071798402: Amazon.com: Books) which is a book covering the high mortality/morbidity rate in General Aviation in the US which kills in the order of 3 x 737 loads of passengers each year in ones and twos!

Fatal-NonIFRvsIFR-1983-2000.png


and

Fatal-StudentandPrivate-SingleEngine-HighPerfomance.png


So even when you have a formal system in place, there is very little to stop someone getting their PPL and flying from farm strips and no-one checking their currency and skills...

Regards
 
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So even when you have a formal system in place, there is very little to stop someone getting their PPL and flying from farm strips and no-one checking their currency and skills...

Regards

Which is a big part of why I'm so hostile towards all this nannying overly formal bullshit that seems to be spinning out of control year on year.

Units having logging devices makes job worse, not better. As in example that you just gave people can just spoof them if they're so inclined, I presume they're the same people who will make up dives in logbooks too.
 
At the moment I am diving Air Dil to 40m with EAN30 and O2 as bailouts and 17/26 Heliair from 40m to 48m, with Bailouts being 20/30, 50/20 and O2. (Accelerated Deco and Counterdiffusion sorted)

So what must I learn in 50 hours that allows me to say dive 60m? (I would then switch to 14/33 HeliAir, same Bailouts 20/30, 50/20, O2)

Instructors comments welcome. :)

Hi, been following the thread, wanting to comment but resisting... Since its Friday night I figured- Why not? :-)

Firstly, an apology, I'm not an instructor and I'm going to comment way off topic... But it's an area of great interest to me and perhaps others.

Uwe is (IMVHO wisely) doing his 50hrs, to 48mtr max. What I'm posting about is his bailouts.

I find it remarkable that an agency requires 3 bailouts for a 48mtr dive, since 50mtrs is a simple single tank OC dive, if you're being super cautious maybe a twinset with a stage of 50% or something. If narcosis is a huge problem then yes I can understand the Trimix, it would be my preference too.

But 20/30, 50/20 and O2? Wow, how long are we going to 48mtrs for?! I can understand perhaps a tank of dil matched Trimix and a little bottle of Nitrox but 3 bailouts, including O2!

Is this another example of bailing out with cautious GF type deco requiring hundreds of stops or just unwarranted concerns by butt covering agencies?

Or am I woefully out of date thinking bailout is an emergency and getting up and out is the priority- rather than doing an OC ascent longer than the planned CCR dive?
 
Hi, been following the thread, wanting to comment but resisting... Since its Friday night I figured- Why not? :-)

Firstly, an apology, I'm not an instructor and I'm going to comment way off topic... But it's an area of great interest to me and perhaps others.

Uwe is (IMVHO wisely) doing his 50hrs, to 48mtr max. What I'm posting about is his bailouts.

I find it remarkable that an agency requires 3 bailouts for a 48mtr dive, since 50mtrs is a simple single tank OC dive, if you're being super cautious maybe a twinset with a stage of 50% or something. If narcosis is a huge problem then yes I can understand the Trimix, it would be my preference too.

But 20/30, 50/20 and O2? Wow, how long are we going to 48mtrs for?! I can understand perhaps a tank of dil matched Trimix and a little bottle of Nitrox but 3 bailouts, including O2!

Is this another example of bailing out with cautious GF type deco requiring hundreds of stops or just unwarranted concerns by butt covering agencies?

Or am I woefully out of date thinking bailout is an emergency and getting up and out is the priority- rather than doing an OC ascent longer than the planned CCR dive?

I don't know what agency he is training with nor which instructor. But I doubt the Agency dictated that he HAD to use those bailouts. Most of the agencies are pretty vague and just say carry enough and appropriate bail outs. If you don't think his are appropriate the training agency is probably not to blame IMHO.
 
Hi, been following the thread, wanting to comment but resisting... Since its Friday night I figured- Why not? :-)

Firstly, an apology, I'm not an instructor and I'm going to comment way off topic... But it's an area of great interest to me and perhaps others.

Uwe is (IMVHO wisely) doing his 50hrs, to 48mtr max. What I'm posting about is his bailouts.

I find it remarkable that an agency requires 3 bailouts for a 48mtr dive, since 50mtrs is a simple single tank OC dive, if you're being super cautious maybe a twinset with a stage of 50% or something. If narcosis is a huge problem then yes I can understand the Trimix, it would be my preference too.

But 20/30, 50/20 and O2? Wow, how long are we going to 48mtrs for?! I can understand perhaps a tank of dil matched Trimix and a little bottle of Nitrox but 3 bailouts, including O2!

Is this another example of bailing out with cautious GF type deco requiring hundreds of stops or just unwarranted concerns by butt covering agencies?

Or am I woefully out of date thinking bailout is an emergency and getting up and out is the priority- rather than doing an OC ascent longer than the planned CCR dive?

I teach TDI, IANTD and PADI. None of them consider a 50m dive a single tank dive

None of them recommend that bailout configuration either.
 
When learning to dive a CCR you have to learn to dive all over again and the more experienced the diver the harder the transition usually is. It seems this is because the experienced diver now needs to "Un-learn" what he has been doing for years which has become automatic and he no longer even needs to think about what he's doing....whereas the novice diver is just learning a different way to dive.

This places all new CCR divers in a similar situation and both are learning to find their way around the unit, new buoyancy skills, more intense pre and post dive planning and checks so it all takes time and there isn't really any way to short cut this....You just need to spend the time learning what you're doing and diving the unit.

Adding mixed gas, carrying multiple bailout tanks and decompression stops etc can very easily overload the novice CCR diver.

I have all my CCR students participate in a "Qualification Dive" to show they are ready to take the next step. This way they can show they are ready to move up or should continue learning at their current level and gain more experience.

Regards,

Lance
 
When learning to dive a CCR you have to learn to dive all over again and the more experienced the diver the harder the transition usually is. It seems this is because the experienced diver now needs to "Un-learn" what he has been doing for years which has become automatic and he no longer even needs to think about what he's doing....whereas the novice diver is just learning a different way to dive.

This places all new CCR divers in a similar situation and both are learning to find their way around the unit, new buoyancy skills, more intense pre and post dive planning and checks so it all takes time and there isn't really any way to short cut this....You just need to spend the time learning what you're doing and diving the unit.

Adding mixed gas, carrying multiple bailout tanks and decompression stops etc can very easily overload the novice CCR diver.

I have all my CCR students participate in a "Qualification Dive" to show they are ready to take the next step. This way they can show they are ready to move up or should continue learning at their current level and gain more experience.

Regards,

Lance


Excellent point, Lance.

+1

Kevin.
 
I don't know what agency he is training with nor which instructor. But I doubt the Agency dictated that he HAD to use those bailouts. Most of the agencies are pretty vague and just say carry enough and appropriate bail outs. If you don't think his are appropriate the training agency is probably not to blame IMHO.

I did mention that I can choose to dive to 40m on Air Dil. There I would use an EAN30, O2 bailout configuration. The O2 has a dual purpose: efficient decompression and safety gas in case a bend diver needs O2 fast.

But below 40m Trimix Dil / Bailouts only.
The 3 bailout selection has been chosen for the following reasons:

1) When I bailout, I want to get to the surface as fast as possible. The bailouts are swapped when the PO2 gets to about 1.0 to 0.8 which assures an efficient decompression profile (ie shortest time out of the water)

2) There are no Counterdiffusion issues when switching from the RB to the Bailout or from bailout to bailout.

3) The 3 bailout configuration can be used from 40m to 60m. (With the appropriate dil of course)

4) The same 3 bailouts will be augmented with a 4th bailout (14/55) when diving from 60m to 100m. Above points 1 & 2 apply.

5) I now own 4 bailout tanks only which will serve me for my future dives to 100m. (1 x 40, 3 x 80)

Please note that these bailout combinations have been designed for deep, long technical cavern / cave dives in mind. Please use the bailout's prescribed by your agency. The above have been determined by a technical diving Team and represent my personal choice not that of any agency.

UweS
 
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