Roadmap from "new diver" to rebreather

[silent running]

Disagree on the SCR, go straight to a CCR.

Al

Hello Josh, I agree with the above, I think SCR is a waste of time, unless you are going the RB80 route and that will be your main tool, which is another subject.

I went to SCR-Dolphin-very soon after I started diving. I would have rather gone to CCR, but there were very few CCR options 10 years ago. After about 3 years and lots of learning/frustration with the limits of diving the Dolphin, I decided to move on to CCR. Luckily, by then there were more options and much more good information available with which to make a decision.

Advanced nitrox in not required in the NAUI course I took for the Prism, only basic nitrox is required. IMHO, it's not really necessary for module 1 non deco diving. Your nitrox course should have given you a good understanding of the concept of partial pressures. Any decent CCR course/instructor will then make sure you understand the hazards of high PO2s and O2 exposure as it applies to CCR diving, as well as proper O2 handling. The benefits of an advanced nitrox course would come mostly from the deco procedures and the extra dive planning skills that it includes. This is certainly valuable training, and is crucial if you are planning to use your CCR for long deco diving. But in my experience, there was great benefit to doing lots of NDL diving on CCR to build up skills, confidence and a better understanding of my CCR before venturing onto CCR tmix training, which in my case included deco procedures and advanced nitrox.

As for attaining good buoyancy and horizontal trim on CCR, I believe this can only come from lots of diving with a CCR. Skills like keeping minimum loop volume and experimenting with weight placement take time to refine. However good my buoyancy/trim on OC and SCR were, it didn't seem to be much help with CCR. It was that different, I felt like I was starting all over again.

So, if you have a good handle on the type of diving you want to do, you can start learning about the different CCRs, their designs and what kinds of diving they are optimized for, as well as the safety issues inherent to CCR diving. It will take some time to familiarize yourself with enough of this to make a decision, so don't rush it. Not to mention that things are changing fast in the CCR market place and it will probably look very different in even 1 year's time. Good luck, -Andy

 

[ken chung ar]

Hello Josh, I agree with the above, I think SCR is a waste of time, unless you are going the RB80 route and that will be your main tool, which is another subject.
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As for attaining good buoyancy and horizontal trim on CCR, I believe this can only come from lots of diving with a CCR. Skills like keeping minimum loop volume and experimenting with weight placement take time to refine. However good my buoyancy/trim on OC and SCR were, it didn't seem to be much help with CCR. It was that different, I felt like I was starting all over again.
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Good luck, -Andy

Hi Josh and Andy,

I have read extensive discussion on questioned usefulness of SCR training for a CCR student diver. I have no intension of repeating that here. I just want to present my case of Evolution CCR training after I had 100 dives with Dolphin SCR, which included pretty hard ones in Palau and Cocos Island.

I completed my Evo training for four days, which was the minimal and shortest. IMHO, the reason why I could do that was that I felt comfortable with the CCR under water in terms of horizontal trim and neutral buoyancy.

As Dolphin is a positive SCR, meaning that Nitrox gas is constantly being injected, you get a gradual increase in your buoyancy and then its sudden loss because it gets vented. I disliked it while I was diving Dolphin. As soon as I got in my first pool session of Evo training, I came to realize that Evo did not give me that trouble and that it was actually EASIER to keep neutral buoyancy with Evo.

I could pay much attention to the Vision computer underwater because I was able to keep my buoyancy without much efforts. That further made it easier for me to accomplish my skills to compensate for too high PPO2 or low PPO2. OC bailout exercise was a piece of cake because I did that a lot while diving Dolphin.

My personal belief is that SCR diving is not a waste of money and time as others think. BTW, I remember that you (silent running) gave me valuable opinions and pieces of info in my days of an SCR diver. I want to express my gratitude to you, although our opinions are different.

Ken

 

[silent running]

As Dolphin is a positive SCR, meaning that Nitrox gas is constantly being injected, you get a gradual increase in your buoyancy and then its sudden loss because it gets vented. I disliked it while I was diving Dolphin. As soon as I got in my first pool session of Evo training, I came to realize that Evo did not give me that trouble and that it was actually EASIER to keep neutral buoyancy with Evo.

Hi kca, I certainly agree that diving a CMF SCR like the Dolphin, is more difficult than CCR. In that sense it does toughen one up for the skills used in CCR diving, given the changing loop volume/buoyancy that happens at regular intervals. The fact that the loop is very near max volume most of the time also requires more weight, which makes the buoyancy shifts more noticeable and adds to the effort/workload necessary to dive an SCR. I felt much lighter and more in control when I switched to CCR so I see your point with regard to the difficulties of SCR potentially making you a better CCR diver.

My personal belief is that SCR diving is not a waste of money and time as others think. BTW, I remember that you (silent running) gave me valuable opinions and pieces of info in my days of an SCR diver. I want to express my gratitude to you, although our opinions are different.

Ken

I certainly respect your opinions kca and I agree with most of what you've said above. And thanks for the compliment, always glad to help. But just to be clear, I meant that SCR is a waste of time and money IF you have the option to move directly from OC to CCR. This is not to say that diving SCR is never a valuable experience, if that is the only choice available to you for whatever reason. But it seems to me that the skill set needed for CCR is specific enough and the investments of time and money significant enough for both CCR and SCR, that it's not the most efficient path to CCR to start with SCR. -Andy

 

[ECVdiver]

You have ment the basic requirments for at least one rebreather that I know of. 50 dives, a basic nitrox cert and AOW is all that is needed to get started. having a rescue class under your belt is always a good idea for any one that is an active diver and will teach you things that you would not learn other wise. The importent thing when taking a step forward in your training is to know and be confident (read not cocky) in the material that you have been taught. 50 dives can mean any number of things 50 of the same dives or were they all different: locations, depths, conditions. It makes all makes a differents.
All that being said the Nautilus CCR is a fine Rebreather that I have been diving for almost two years. I have had a great deal of pleasure diving this unit from the northen coast of california down to baja. Rebreather Nautilus CCR Closed Circuit Rebreather is the web site and I have found that the ease of use and setup of the unit is a great benifit for any CCR diver.

 

[sunkmail]

Advanced nitrox in not required in the NAUI course I took for the Prism, only basic nitrox is required. IMHO, it's not really necessary for module 1 non deco diving. Your nitrox course should have given you a good understanding of the concept of partial pressures. Any decent CCR course/instructor will then make sure you understand the hazards of high PO2s and O2 exposure as it applies to CCR diving, as well as proper O2 handling. The benefits of an advanced nitrox course would come mostly from the deco procedures and the extra dive planning skills that it includes. This is certainly valuable training, and is crucial if you are planning to use your CCR for long deco diving. But in my experience, there was great benefit to doing lots of NDL diving on CCR to build up skills, confidence and a better understanding of my CCR before venturing onto CCR tmix training, which in my case included deco procedures and advanced nitrox.

One thing to consider - with a CCR you have one tank that is 100% O2. Without an advanced nitrox c-card, any responsible shop won't fill your tank with anything above the 40% of the standard nitrox. Even if you never use O2 for deco or bailout, you can still easily, and often do, use high concentrations of Oxygen in the loop of a CCR.

When I did my CCR Course, advanced nitrox wasn't a prerequisite, but doing the advance concurrently with the CCR was a requirement. It isn't really a lot of work, and I believe you really don't NEED advanced before hand ... going the cuncurrent route is easily enough.

I hope this helps to clarify things

 

[silent running]

One thing to consider - with a CCR you have one tank that is 100% O2. Without an advanced nitrox c-card, any responsible shop won't fill your tank with anything above the 40% of the standard nitrox. Even if you never use O2 for deco or bailout, you can still easily, and often do, use high concentrations of Oxygen in the loop of a CCR.

When I did my CCR Course, advanced nitrox wasn't a prerequisite, but doing the advance concurrently with the CCR was a requirement. It isn't really a lot of work, and I believe you really don't NEED advanced before hand ... going the cuncurrent route is easily enough.

I hope this helps to clarify things

Hello sm, I had a similar concern when I got my NAUI CCR card and I asked my instructor if I would have any problem getting O2 fills from a dive shop, given that NAUI only requires basic nitrox. He told me that anybody who recognizes the card would give me an O2 fill. So far, after diving the Prism for 6 years in the US, Canada and all over the Caribbean and Asia, I've had no problem getting O2. But, IIRC, here in the US, you don't need a prescription to obtain O2 from a gas supplier. If this is correct, then a dive shop would have to be really looking for an excuse not to fill it, maybe reading into some of the fine print on their liability insurance. My assumption is that if the shop recognizes the certifying agency, they will then not be at risk for selling the fill if the card says the diver is qualified to purchase it, given that a c-card/agency is all any dive shop ever has to go on as to whether the diver is qualified to receive it's services at any given point.

IIRC, the Posieden MK6 will not require advanced nitrox for the mod 1 course and has a whole new certifying agency to go with it. NAUI already does not require advanced nitrox, as mentioned above. The trend for entry level CCR training seems to be less requirements, not more. Whether you agree with this or not is another matter, but my guess is that whatever small amounts of skepticism about filling O2 for a CCR diver are floating around, they will continue to diminish and are in any event, entirely dependent on whether the dive shop recognizes the certifying agency. -Andy