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Alright i get that, and that somehow answers a question i got in my head. To reach the experience i need for ccr i can dive my setup as it is now. There are no special skills youll learn on doubles which are key for ccr ?
No, there are no special skills that doubles will teach you that are a must for CCR. I went from a single tank rec dive setup to CCR and never looked back.

Here are the skills you must have before going to CCR:

- Buoyancy. You must have perfect buoyancy control. You'll have to re-learn it when you go CCR, but knowing what good buoyancy is like will help you re-learn faster. If your buoyancy sucks on OC and you haven't mastered it, prepare for a lot of suck on CCR.

- Trim. You must know what good trim looks like and be in good trim - not seahorse.

- Regular dive drills must become automatic. You should not struggle with SMB deployments and various fining techniques. If you want to go overhead, you must master modified frog kick. Also, reel work. You must be comfortable with reels/spools. Watch what guys do in caves and try to do that in open water. For example, if you can run a spool while staying neutrally buoyant in 3-4m, you'll be ready. Most essential drills don't require doubles, CCR, or cave environment at all; see the details below.

- Gas switches. This may help but is not mandatory. In the first CCR class you may learn the SCR mode which requires a proper gas switch procedure. So you must know how to ensure that you're plugging the right gas, etc. Your CCR instructor will teach you that.

So how do you train? Get training standards from any agency and see if you can meet those. Here is what GUE recommends for its rescue class:

a. Must be able to swim at least 300 yds/275 m in less than 14 minutes without stopping. This test should be conducted in a swimsuit and, where necessary, appropriate thermal protection.

b. Must be able to swim a distance of at least 50 ft/15 m on a breath hold while submerged.

c. Demonstrate proficiency in safe diving practices, including pre-dive preparation, in- 
water activity, and post-dive assessment.

d. Demonstrate awareness of team member location and a concern for safety, responding 
quickly to visual indications and dive partner needs.

e. Efficiently and comfortably demonstrate how to donate gas to an out-of-gas diver in 
multiple gas-sharing scenarios.

f. Demonstrate a safe and responsible demeanor throughout all training.

g. Demonstrate proficiency in surface marker buoy deployment.

h. Demonstrate good buoyancy and trim, i.e., approximate reference is a maximum of 30 
degrees off horizontal while remaining within 5 ft/1.5 m of a target depth.

i. Demonstrate three propulsion techniques, including comprehension of the components 
necessary for a successful backward kick.

j. Demonstrate effective proficiency with proper ascents and descents, including the 
implementation of variable ascent rates.

k. Demonstrate effective navigation using a compass and managing a spool as a guideline 
underwater.

l. Demonstrate proficiency in fundamental diver rescue techniques, including assessing a 
rescue scene, supporting and recovering distressed, tired, and unconscious divers at the surface, recovering an unconscious diver to the surface, and a range of simulated diving incidents.

Cheers~
 
This quote concerns me more than anything. You take an SSI deco class and 40% is in the "mix" somehow?

Wait.....why?

Lets do a dive to 25m for an hour. That's a 1.4bar O2, CNS of about 50% and around 100 OTU's. A 10 minute stop with gfHI of 70.

Seems reasonable?
 
Wait.....why?

Lets do a dive to 25m for an hour. That's a 1.4bar O2, CNS of about 50% and around 100 OTU's. A 10 minute stop with gfHI of 70.

Seems reasonable?
This is a tech forum, I would be very surprised if anyone that has tech training, or a tech instructor, would suggest diving 25m/82ft on 40% nitrox.

IMHO, its not reasonable. But, maybe I'm in the minority here?
 
Never seen anybody dive a 40/0. Much more common to see 32/0 and 36/0 for main gas; deco typically 50/0 and 100/0. Anything in-between is theoretically possible but I have never seen it used in practice. There may be cases where you top up a tank and end up with a weird mix but never seen by choice.
 
Never seen anybody dive a 40/0. Much more common to see 32/0 and 36/0 for main gas; deco typically 50/0 and 100/0. Anything in-between is theoretically possible but I have never seen it used in practice. There may be cases where you top up a tank and end up with a weird mix but never seen by choice.
i still have my normal 21% Air as a back gas in my 15l Tank at 200 Bar. Just in my 80 cuft stage is up to 40% EAN for deco.
 
This is a tech forum, I would be very surprised if anyone that has tech training, or a tech instructor, would suggest diving 25m/82ft on 40% nitrox.

IMHO, its not reasonable. But, maybe I'm in the minority here?
Pure speculation on my part after reading this thread, but it seems like a convoluted way of dealing with redundant gas in a deco dive. Because there is no twinset or side mount tanks to offer gas redundancy at depth, the deco gas is specified to be "breathable" at depth to offer some redundancy. I don't see any other reasons to limit the deco gas to <40% O2. Doubles + a real deco gas sounds more reasonable to me, but then again I'm not tech trained yet.
 
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