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~
