sanctum

[Deep Thought]

Down in Playa ccr diving the Cenote's and have limited wireless, but will try.

No real reason that you can't integrate a FFM on a rebreather, other than you need to have a good oral nasal pocket that does not pool Co2, and you must have a tight seal.  Some FFM that I have used in past relied on a positive pressure, which is not the case in a rebreather (ambient pressure).  During the Doty filming, the production company asked the "team" to use FFM, just like the episodes of "Deep Sea Detectives"...but due to the depth and challenges I voted that this would not be a good idea for the filming.  There is a Drager full face that some divers choose to integrate with full face and I know at least Megalodon ISC purchased a few of these and sold them as a kit to add to ccr's. 

If the second question is about buddy breathing on a ccr, sure anything is possible.  It is not taught in any of the courses that I offer...but when it comes straight to the point of survival then anything that works works.  When you take the DSV (dive surface valve "mouthpiece") out of the divers mouth, then it must be closed.  The most practical position to do this would resemble a vintage double hose with one diver riding "piggy-back" and passing the hose overhead, then back down.  It would require oral purging of the mouthpiece to vent the small amount of water that would ingress otherwise.

Perhaps I can offer a rebreather demo at Aquaventure and if divers want to try the buddy breathing technique, I can demonstrate this. 

Personally my experience on FFM has not been positive enough to warrant the extra effort required - you don't get anything for free and with a FFM you have drawbacks that to me do not yield a postive.

Cenotes are excellent and the weather is here, wish you were beautiful ...

Time for Cervezas!

Ron