Rebreather DIR?

[cornfed]

With surface supplied gas you can run a small continuous flow in the mask (or hat) because you don't need to worry so much about gas consumption.

Thanks!

 

[MHK]

Why don't commerical divers have this problem?

In a commerical dive team [ and bear in mind I'm NOT a commercial diver], but the tender can regulate the flow to limit C02 accumulation .. Commercial diving is vastly different from recreational scuba diving, and certainly the support staff and team dynamic that is mandated under commerical diving is much better then what you see in a typical recreational based scuba "team"..

Surface supplied gas using FFM's differ substantially from a recreational diver using a FFM, and I've certainly never seen a recreational diver using a hard hat ;-)

Hope that helps..

 

[salty]

You are only doing a partial analysis, which is inconsistent with DIR positions. FFM's for use as a diving tool brings with it a host of problems, the least of which is donating a long hose. Particularly when you are discussing working at depth, the dead air space in the FFM allows for an unnecessary risk with respect to C02 accumulation..

As for RB's in a DIR-F I'm not al all where you got that one from, but I can assure you that no one will have a RB in my DIR-F class.. RB's do have an application in certain dives, but they require specialized training and are beyond the scope of DIR-F classes.

Hope that helps.

Mike:
Long time ago I heard from a reliable source that a DIR/GUE diver used a FFM when spending a long time on O2. I would think this is no longer practiced with air breaks now being the norm. Was this a practice that is more associated with the WKPP exploration dives verses ocean tech level dives.

Is this practice used at all any more....Im guessing its not but I have never heard the offical statment that FFM are no longer used at all because.......

Im guessing that what I heard was probly from the early days of DIR and has since gone the way of the dinosuars.

 

[MHK]

Mike:
Long time ago I heard from a reliable source that a DIR/GUE diver used a FFM when spending a long time on O2. I would think this is no longer practiced with air breaks now being the norm. Was this a practice that is more associated with the WKPP exploration dives verses ocean tech level dives.

Is this practice used at all any more....Im guessing its not but I have never heard the offical statment that FFM are no longer used at all because.......

Im guessing that what I heard was probly from the early days of DIR and has since gone the way of the dinosuars.

My sense is that was before the habitats were put in, but I couldn't say for certain. I do seem to remember something along those lines but that was before my time, perhaps if Chickdiver is following this thread she can comment.

The other thing to consider, is that using a FFM isn't necessarily a death sentance at 20'. The concern many of us have with using FFM's during the dive portion of the dive is that if you start working harder, swimming against currents, or as many do breath the wrong gas at depth, you start adding to what can accumulate C02. Whereas when you juxtapose that agaisnt using a FFM while resting at deco at 20' you can see that the possibility for C02 retention is greater at depth while working versus resting at 20'..

Hope that helps..

Later

 

[MarcHall]

I've been researching for DIR-F and I cant understand how a rebreather is acceptable and a FFM is not. Both cannot be used like a long hose to share air. If comms in FFMs can improve communications dramatically, does anyone speculate as to whether or not they will be incorporated into DIR in the future?

Thank you.

Rebreathers are not used in DIR-F

I believe your question results from a misunderstanding on how the RB-80 is dived in a DIR configuration.

In a DIR RB-80 configuration the diver wears a full DIR Open Circuit configuration. The necklace regulator is in place as is the long hose reg. The long hose reg is donated to the buddy during an OOA. The breather is driven by the backgas tanks or by a stage bottle. The RB-80 diver can at any time switch from breather to Open Circuit.

Enjoy your DIR-F course.

Marc Hall
www.enjoythedive.com
www.sdue.org

 

[FFMDiver]

Interesting but a little hard for me to follow. Would you consider FFMs w/ no SSA to place divers more at risk for shallow water blackout?
Thank you.

My sense is that was before the habitats were put in, but I couldn't say for certain. I do seem to remember something along those lines but that was before my time, perhaps if Chickdiver is following this thread she can comment.

The other thing to consider, is that using a FFM isn't necessarily a death sentance at 20'. The concern many of us have with using FFM's during the dive portion of the dive is that if you start working harder, swimming against currents, or as many do breath the wrong gas at depth, you start adding to what can accumulate C02. Whereas when you juxtapose that agaisnt using a FFM while resting at deco at 20' you can see that the possibility for C02 retention is greater at depth while working versus resting at 20'..

Hope that helps..

Later

 

[salty]

Thanks Mike

 

[cornfed]

In a DIR RB-80 configuration the diver wears a full DIR Open Circuit configuration. The necklace regulator is in place as is the long hose reg. The long hose reg is donated to the buddy during an OOA. The breather is driven by the backgas tanks or by a stage bottle. The RB-80 diver can at any time switch from breather to Open Circuit.

Is the backup also run through the breather or is it OC? Do you need to do something to switch between open and closed circuit?

 

[MHK]

Interesting but a little hard for me to follow. Would you consider FFMs w/ no SSA to place divers more at risk for shallow water blackout?
Thank you.

The point that I was trying to highlight was that when issuing blanket ideas like diving with, versus without, a FFM doesn't speak to the totality of the issue. Most who use a FFM do so for the entirety of the dive, which means at depth and possibly using air at depth. If you now add to the equation some current, possible overweight or any number of combinations of less then efficient diving protocols then the increase chance of retaining C02 becomes a concern.. SSA helps due to the flow regulation, but for recreational divers there seems to be little, to no benefit, of using FFM's whereas the added risk seems to concerning for me..

Hope that helps..

Later

 

[Spectre]

In a DIR RB-80 configuration the diver wears a full DIR Open Circuit configuration. The necklace regulator is in place as is the long hose reg. The long hose reg is donated to the buddy during an OOA. The breather is driven by the backgas tanks or by a stage bottle. The RB-80 diver can at any time switch from breather to Open Circuit.

I understand the config, and I understand you can just toss the breathing loop back over your shoulder to go to open circuit, unclip the primary and you're switched over. But if your buddy has an OOG emergency what's the procedure? You obviously can't deploy the long hose, since it's clipped off as well as locked by the breathing loop. Is it that they always will have had to bail to OC anyway? When one buddy bails to OC, do they both [so the long hose is ready for deployment?]