A lot depends on circumstances ...calm seas and little current are easier to handle than heavy seas and lots of current for example. If I was concerned I'd have the 50 or 21/35 deployed, if I was less concerned I would have my hand on second stage and have this breathable gas on top and turned on, If I wasn't concerned at all I'd be dropping quickly to 10m, very aware that the bailout is not accessable and I must go to stage. No matter what diluent I am diving I always make sure the unit is functioning completely, only add O2 at surface (except to check ADV) and monitor my PO2, loop volume, whether ADV is firing etc etc very carefully near the surface
GUE CCR, It's OFFICIAL
- Thread starter scubainchicago
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A lot depends on circumstances ...calm seas and little current are easier to handle than heavy seas and lots of current for example. If I was concerned I'd have the 50 or 21/35 deployed, if I was less concerned I would have my hand on second stage and have this breathable gas on top and turned on, If I wasn't concerned at all I'd be dropping quickly to 10m, very aware that the bailout is not accessable and I must go to stage. No matter what diluent I am diving I always make sure the unit is functioning completely, only add O2 at surface (except to check ADV) and monitor my PO2, loop volume, whether ADV is firing etc etc very carefully near the surface
scubainchicago
Member
These are some of the things we discussed during our course as well and they all make sense depending on dive site conditions. The only thing that makes this different is the way travel gas is delivered. As far as ascents, doing a stop at 25' at 1.6 ppO2's to keep a breathable gas at the BOV/Necklace. The other option is to deploy a deco gas depending on surface conditions. The team will ultimately make a call and address accordingly. As of now, I haven't heard any talk of QD's for addition of breathable gasses. There's a reason it's been beaten into us that it's the kill zone.
Having a deco gas reg drapped over the top of your loop seems pretty hooky
Not sure I understand this. If you have 10/70 in your backmount dil/BO for a 275ft dive the primary BO via the necklace is not breathable <20ft. Honestly I am not as concerned about the end of the dive, but a lot of issues do crop up at the very start of dives and panicky switches to any gas, worst of all a hypoxic gas, are bad news.
The RB80 has a switchblock and a BOV to address this. GUE's CCR solution seems more ad hoc. Perhaps it is still to be developed, I just hope nobody gets hurt in the process of developing a standard.
Dil will kill, dil will kill, dil will kill is what I repeat to myself
How does RB80s BOV address this? THe BOV is fed from back gas so is no different to CCR with necklace or BOV (both Jarrod and Richard Lundgren both dive with BOVs on their CCRs)
You can feed the BOV from 50% via the switchblock (well I thought you could, perhaps not) Although its somewhat apples to oranges since the RB80 isn't used as an SCR at all shallower than 20ft. So there's no bailing out since they are already on OC.
So is there no standard between BOV and necklace on the GUE-JJ? Diver choice?
Mr fish
Active Member
best to keep the adv off till your past 6m , and turn it off on the way back around 15m /12m one less thing to fook up on you , well thats what i find ,
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BOV feeds from Back gas on RB80. Plugging drive gas into RB80 is in a sense no different to the solenoid.
There are only slight functional differences between BOV and necklace so I think its fine to leave it to diver choice (CE is a hurdle here)
This is a drawback of diving combined dil/primary bailout. I started this way, but have come to the conclusion that I don't want to continue with a large source of combined dil/BO. It presents many problems for my target (cave) exploration dives. Not all caves stay deep for example. Having a 220ft deep sump followed by 400ft (horizontal) of 10ft deep water is not a very friendly profile for this setup. Especially if you go with 10/70 in the backmounted 50s because you don't know in advance how deep the sump will go and have no idea the cave is shallow beyond.
ps, I don't have a JJ, just looked at the configuration during my planning/configuration buying phase.
PeterN
Active Member
There are only slight functional differences between BOV and necklace so I think its fine to leave it to diver choice (CE is a hurdle here)[/QUOTE]
Interesting perspective. I feel that there is a huge functional difference between these two.
I ran a BOV for quite some time and one of my reasons for ditching it was the huge functional difference between always having a breathable gas to go to between those two systems.
With the BOV I had a qc6 connection to plug, unplug, plug, unplug and plug again.
With the DSV I clip a breathable gas to my neckless. I change it out appropriately.
With the BOV I w as often with no gas to the BOV.
With the neckless I allways have a breathable gas to at hand.
Peter
Interesting perspective. I feel that there is a huge functional difference between these two.
I ran a BOV for quite some time and one of my reasons for ditching it was the huge functional difference between always having a breathable gas to go to between those two systems.
With the BOV I had a qc6 connection to plug, unplug, plug, unplug and plug again.
With the DSV I clip a breathable gas to my neckless. I change it out appropriately.
With the BOV I w as often with no gas to the BOV.
With the neckless I allways have a breathable gas to at hand.
Peter
Mark Chase
ATB=AlwaysTalkingBollocks
Interesting perspective. I feel that there is a huge functional difference between these two.
I ran a BOV for quite some time and one of my reasons for ditching it was the huge functional difference between always having a breathable gas to go to between those two systems.
With the BOV I had a qc6 connection to plug, unplug, plug, unplug and plug again.
With the DSV I clip a breathable gas to my neckless. I change it out appropriately.
With the BOV I w as often with no gas to the BOV.
With the neckless I allways have a breathable gas to at hand.
Peter[/QUOTE]
Why not just the same of board pluggable system for the BOV?
I used to do it that way but got fet up maintaining the QDs so went to hard wired off board.
If i want to i can unscrew any off board reg and screw the LP hose on to my BOV
ATB
Mark
PeterN
Active Member
Not me because mine can't.
I pretty much run the same 10/50 dil for all but the deepest dives. I do not have it plumbed to be able to breathe it directly.
Peter
PeterN
Active Member
Why not just the same of board pluggable system for the BOV?
I used to do it that way but got fet up maintaining the QDs so went to hard wired off board.
If i want to i can unscrew any off board reg and screw the LP hose on to my BOV
ATB
Mark[/QUOTE]
Were I still running a BOV I think I would try this idea. The qc6 fittings are a pos to switch out n heavy gloves when things are happening.
This still leaves you with times with no gas to the BOV.
Peter
I used to do it that way but got fet up maintaining the QDs so went to hard wired off board.
If i want to i can unscrew any off board reg and screw the LP hose on to my BOV
ATB
Mark[/QUOTE]
Were I still running a BOV I think I would try this idea. The qc6 fittings are a pos to switch out n heavy gloves when things are happening.
This still leaves you with times with no gas to the BOV.
Peter
Mark Chase
ATB=AlwaysTalkingBollocks
Only reasion id need to do this is if i need SCR to extend my bailouts. If I didnt id just go on to my OC regs
SO SCR Id do loop flush go on loop and change the feede supply to the BOV whilst SCR on loop
Thers an argument for swaping my bailout feed on shalow deco if I was diving 6/80 or something daft but Id probably take my chances on a couple of breaths off the BOV whilst I sorted out an OC reg.
ATB
Mark
gaucho
New Member
Sorry guys, this is interesting to me, since Im still kind of working out which system I prefer for everything on my JJ. Why would you go plugging and unplugging the QC for the BOV? I mean this only makes sense to me if my main BO would be hypoxic. And it would only apply if using 10/50 or something like that.
I don't have much experience below 60m, so I might be looking at things wrong. But I will take a shot at understanding this.
Letme rephrase to see if Im understanding correctly and Im expressing myself correctly; I rather have BailOut connected to my BOV which matches my diluent (under the principle that diluent and BO should be the same, and they would be whatever backgas you would use on a similar OC dive). Now, my BOV is connected to the BO which matches the diluent. Theoretically, except on very low hypoxic mix, I could jump to that BO whenever I wanted. Even if Im decoing at 36, 21 or even 6 (metric), I could jump to the BO on the BOV because I need to get out of the loop, and then once on BO, deploy whatever second stage is attached to the correct bottle for that stage of the deco, following gas switching procedures, etc. It would then make it very compatible to usual Trimix and Adv Trimix gas switching and team diving protocols.
So I would not really use the QD for anything but assembly/disassembly really. I would carry BO on a separate bottle (or if using big backgas on the JJ, attach it to the 2x50s or 2x40s with lola valves) and then connect that to the BOV. Unless diving very hypoxic gas (10/50 for example would be the only one which would not work at 6m), this would work for every dive.
Is there something Im not seeing here? Thanks!
I don't have much experience below 60m, so I might be looking at things wrong. But I will take a shot at understanding this.
Letme rephrase to see if Im understanding correctly and Im expressing myself correctly; I rather have BailOut connected to my BOV which matches my diluent (under the principle that diluent and BO should be the same, and they would be whatever backgas you would use on a similar OC dive). Now, my BOV is connected to the BO which matches the diluent. Theoretically, except on very low hypoxic mix, I could jump to that BO whenever I wanted. Even if Im decoing at 36, 21 or even 6 (metric), I could jump to the BO on the BOV because I need to get out of the loop, and then once on BO, deploy whatever second stage is attached to the correct bottle for that stage of the deco, following gas switching procedures, etc. It would then make it very compatible to usual Trimix and Adv Trimix gas switching and team diving protocols.
So I would not really use the QD for anything but assembly/disassembly really. I would carry BO on a separate bottle (or if using big backgas on the JJ, attach it to the 2x50s or 2x40s with lola valves) and then connect that to the BOV. Unless diving very hypoxic gas (10/50 for example would be the only one which would not work at 6m), this would work for every dive.
Is there something Im not seeing here? Thanks!
opheim
CCRX Supporter
The argument is exactly that - having hypoxic mix as dil/deep bailout in the manifolded twins, connected to BOV or necklace reg means breathing that <6m is not a good idea. Using standard gases with the "one deeper" strategy means anything deeper than 60m would be 12% or less O2. Even 45-60m would be 15% which is also pretty much hypoxic in anything but relaxing state at surface.
Which is why you'll be looking at other options to meet this challenge.
Which is why you'll be looking at other options to meet this challenge.
PeterN
Active Member
I see no reason fo my BO to match my dil. I do see the need for appropriate BO for whatever depth I might get to. I have not heard of the principle you refer to.
The reason for pluging and upluging different gasses is simply to have a breathable gas to the BOV at all times.
Your BO gas will become deco gas if you loose your loop. However going to BO is often not the same as switching to a different tank for deco. Going to BO is by definition unplanned. That is why the BOV hasit hands down over the DSV for the ease of switching to oc. But, there are issues. Mostly for using hypoxic gasses. There is of course the possibility of a caustic cocktail. This would mean that a BOV becomes unusable. More problematic in my view is the "simple" problem of how to assure allways having a breathable gas to bail to when diving hypoxic gasses.
It almost seems like GUE does not really believe in bail out for CCR. Not in the same way that I view it at least. The explanations on here have been candid, but not well thought out. You all keep referring to your deco gas...
For me I have decided on a few "principles" for BO. They include that it be to hand at all times and always be breathable. It also needs to be easy to look after.
It was easy to run a BOV in the shallows. Not quite as simple to assure a breathable gas when running deep. For these reasons I have gone back to a DSV and I move the regs around to my neckless and always have something to go to.
It really does seem to me that GUE is atempting to run the ccr as an open circuit rig with an add on.
In my very limited experience with ccr, most problems happen in the first few min of the dive. I would hate to see someone jump in with a rig set to dive deep only to find a problem in the shallows and find they had forgotten, or not planned to, have a "deco" reg draped somewhere handy.
It may well be that I do not understand the plan for GUE ccr bail out. So far I have not found any GUE ccr divers who can clearly articulate one.
Safe diving,
Peter
Richard Lundgren
New Member
Hi Peter
We do love the idea of being able to bail out
Designing a perfect system for all occasions is however hard. We are not claiming to have one strategy that is without any complications for conceivable situations. The following can serve as a introduction to our reasoning.THE D7 BAILOUT SYSTEM
Numerous accident incidents over the years have had tragic and fatal outcomes due to inefficient and insufficient bailout procedures and systems. No industry standard exists detailing how;
• bailout gas reserve volumes should be established
• to contain and access the bailout gas
• To chose bailout gas properties
The following bailout system description is designed for the GUE holistic gear configuration, GUE Standard Operating Procedures and GUE diver training. Removal any of these components and the true value and usefulness of the system is jeopardized.
BAILOUT GAS RESERVE VOLUMES
The volume needed to sustain a diver while having to bailout from a rebreather is difficult to assess as many different factors impacts the result. Stress, Co2, Respiratory rate, depth and time are but a few of these variables. All reserve gas calculations may be appropriate under ideal conditions and circumstances but should be regarded as estimates or predictions at best.
The gas volume needed for two divers to safely ascend to the first gas switch is referred to as Minimum Gas (MG) for SCUBA divers. The gas volume needed for one rebreather diver to ascend on open circuit during duress is referred to as Bailout Gas Reserve (BGR). A recommended 20 liter per minute surface consumption rate (SCR) multiplied by 1.5 to account for duress is recommended to be used.
THE CAT-FORMULA
CAT= Consumption x 1.5, Average ATA, Time
BGR = C x AvP x T
Even if catastrophic failures are unlikely thus, in theory, making the BGR conservative, other factors like hypercapnia (CO2 poisoning) and stress warrants a cautious approach.
Decompression bailout gas volumes are calculated based on the divers actual need and no additional reserve is added.
GUE does not endorse the use of “team bailout” i.e. when one divers carries bottom gas bailout and another decompression gas based on only one divers need. A separation or equipment failure would quickly render system like this useless.
CONTAINING AND ACCESS
In order to contain the BGR volumes a redundant open circuit system consisting of two 7 liter 232 bar cylinders is used. These tanks are linked together using a flexible manifold. This system holds up to 3250 liter of gas of witch only roughly 10 % is used by the rebreather as diluent. Hence close to 3000 liters can be reserved for a bailout situation. This gives a tremendous capacity in a relatively small form factor and the flexibility needed for dives requiring additional gas reserves (when direct ascent is not possible or desirable). The following advantages were considered when designing the bailout system:
• The D7 system is consistency with existing open circuit systems utilized by GUE divers. A bailout system that is familiar to the user will not increase stress levels witch is important. A GUE diver will rely on previous experience and procedures when most needed.
• The D7 system contains the gas volumes needed according to the GUE BGR calculations as well as the diluent needed. Allows for a vide range of dive missions.
• The D7 system is fully redundant and has the capacity to isolate failing components and still allowing full access to the gas.
• The D7 system overall weight is less compared to a standard system with an AL11 liter bailout cylinder. The D7 system contains 800-900 liters more gas available for a bailout situation compared to the AL11 liter system. Lead has been traded for gas.
• The D7 system does not occupy a stage spot allowing for more additional stages or decompression bottles to be added.
• The D7 system can with ease be separated without losing any gas if desired during transport.
The bailout gas can be accessed quickly by the bailout valve (BOV). This gives the user an effortless transition from the loop to the open circuit system. After evaluation the situation, breathing open circuit gas from the BOV, the user transition to the long hose high performance regulator is the situation calls for a full bailout and termination of the dive.
The long hose is carried under the loop when diving the rebreather. The chances of having to donate to another GUE rebreather diver is indeed low as both carries redundant bailout. Still GUE maintains that the capacity to donate gas must be present. The donation process is more likely to involve a hand over of the long hose rather than a donation. Still if needed such a donation is made possible by either removing the loop temporarily or by simply donating under the loop. If a diver bailout, all team divers prepare for the eventuality of a low gas situation by placing their long hoses on top of the loop.
Bailout decompression gasses is contained and carried in decompression bottles. If more than three bottles is needed the shallowest bottles are carried on a stage leech. Maintaining bottle rotation techniques and capacity thru regular practice is important and challenging as this skill is rarely used.
Bailout gas properties.
The choice of bailout gas is extremely important as your life may well depend on it. It is not only the volume that is important, the individual gas properties will decide if the bailout gas will be optimal or not. As the D7 system contains both the diluent and bailout gas both gasses share the same characteristic. The following gas characteristics must be considered when choosing gas:
• Density. The equivalent gas density depth should not exceed 30 meters. Ventilation is impaired when diving due to several factors increasing the work of breathing (WOB) and diving rebreathers even more so. High density of gas, such as gasses containing no or low fractions of helium, decrease the divers ventilation capacity significantly and increase the risk of dynamic airway compression. Co2 washout from blood depends on ventilation capacity and can be hindered if a high-density gas is used. The impact of density is very important and the risks of using dense gases not to be neglected. This effect is not limited to deep diving, using a dense gas as shallow as 30 meter reduce a divers ventilation capacity with a staggering 50 %.
• Narcotic potential not to exceed 30 meters. Rebreathers and emergency situations are complex enough without further being aided by narcosis.
• PPO2 limited to allow for long exposures. Max ppo2 for bottom gasses is 1.2 PPO2, 1.4 PPO2 for deep decompression gasses and 1.6 PPO2 for shallow decompression gasses. Caution should be taken when the bailout strategy involves switching to a hypoxic gas. As in any open circuit operation involving hypoxic back-gas, hypoxic zones needs to be defined. Switching to the BOV inside a hypoxic zone will likely result in an incident. This is a weakness in the system but can be addressed in the same way as during open circuit diving. While on the loop a rebreather should be used as a oxygen rebreather shallow and on the surface.
Regarding diluent/bailout gas the next deeper GUE standard bottom gas is recommended diving rebreathers in combination with the normal GUE standard decompression gasses.
Bailout gasses are not chosen in order to give shortest possible decompression obligation. They are chosen in order to give you the best odds of surviving a potentially life threatening situation.
SUMMARY
The D7 bailout system is flexible and can contain the diluent as well as bailout gas reserves and additional gas reserves needed for a range of different missions. The familiarity the system gives GUE divers along with the knowledge that ample of gas reserve is carried gives piece of mind. The choice of gasses with properties designed to aid a diver in duress dealing with an emergency completes the system.
Factors like ease of climbing ladders and a few minutes of more decompression have not been prioritized outlining the D7 bailout gas reserve system. A few sessions at the gym combined with aquatic comfort deals with these factors in a more appropriate way . Nothing prevents a complete removal of the entire system at the surface if an easy exit is needed.
Richard Lundgren
New Member
Hi Mark
Having Tech 2 as the entry level makes sense for us right now due to a range of reasons. Will T2 always be the requirement? Nothing is written in stone but for the immediate future we don't see compelling reasoning for lowering the requirement but things may change and then one could argue for Tech 1 with experience.
Let us run with the ball for a while and then revisit and evaluate