Welcome to Rebreather World, Chris.
Quote: (Originally Posted by
Dawktah)
1. I have improved my SAC significantly over the 27 dives but only CCR will keep me down longer than my wife!
Is this a safe practice to be diving CCR while your buddy is diving OC?
They cheat. I don#t know how, but they cheat.
No problem diving with an OC buddy as long as they know a bit about breathers, what to look for (bubbles mostly) and what not to do. The link to Divemole's website above is a good one, IIRC the current Ambient Pressure manuals also give some info in that regard.
Quote:
2. Can you donn a CCR in the water attached to a tether? This is the OC technique I am using now from a 15ft. RIB. I am not sure when I'll be able to afford a larger one 20-25ft.
Even then I don't know how easy or difficult it will be to donn a CCR on board and roll in.
Shouldn't be a problem, you'll doff and don the Rebreather underwater during class.
On the other hand I did side rolls off a RIB with the SportKiss without problems, one of the guys that day dove an Evolution and rolled off, too. The RIB was larger than 15ft, though.
Quote:
3. Is the Sonolime (sp?) special for diving or is it (can you use) standard soda lime that is used in Anesthesia?
Yes, there is diving grade Sofnolime (797 I believe) in 8-12 mesh, as well as 4-8 mesh. Also popular, especially in the US, is Sodasorb from Grace in either 6-12 mesh or 4-8 mesh. Dräger manufactures Dive Sorb in 5-9 mesh. IIRC the main difference to medical sorb is the water content for diving applications.
Quote:
4. Is there a CCR that the mouthpiece and HUD is better suited to use with a camera?
Mouthpieces and HUDs have been discussed quite a bit. Use the search function for DSV, BOV, HUD and HDD. And have a look in the library.
Personally I've used the former with (BOV) integrated bailout second stage and without (DSV). I very much prefer the BOV.
I also dove RBs with and without HUD and much rather have a HUD than not.
But that's very much a personal preference, as is most everything else about RBs.
Quote:
5. Do you need to start with SCR and then go to CCR, or can you just start with CCR?
Pretty much the same as above, this subject has been hotly debated. And in the end there is no right or wrong way. Some people who went from SCR to CCR said it was a waste to dive SCR first, others will tell you they gained experience they wouldn't want to miss.
I tried SCR and CCRs with instructors, watching them setting up the RBs and pre-diving them. Tried them out. Watched the post dive. And decided to go straight to CCR.
I highly recommend you have a look around what's on the market and try what you think might work for you. Then find an instructor and do an intro. Nothing like some 1st hand experience with both the unit and the instructor, and it's plenty of fun.
Quote:
6. Are the gas cylinders/valves unit specific or are they standard Al diving cylinders? Do the cylinders follow the same annual viz and 5 year hydro req.?
Most RBs use standard SCUBA tanks, though usually smaller ones than OC. 2 and 3 ltr are most common for CCRs, 4 ltr for SCRs. Viz and hydro are the same. The few models that use non-SCUBA tanks are usually old, military or both. Those tanks can be quite expensive, hard to source, and a pita to deal with as they usually don't have DOT stamping, need X-ray testing etc..