Favourite bailout gases

Drmike · 9th February 2006, 14:11

Quote: (Originally Posted by Mark Chase)

Personally I have done the Mod3 trimix CCR course but it didn't teach me anything new that would help with this question. Im my mind any sort of bailout plan that involves using the CCR is unacceptable. Bailout plans for me are OC based. Anything else is semi Alpinist. I didn't need a CCR based training to let me figure out an OC decompression form X depth and then include a suitable travel gas to get from depth to deco mix.

Personally I think the fixed syllabus TDI trimix training for Mod3 is rubbish. There are instructors out there who are writing their own syllabus and in one case i am aware of he is writing a proper CCR based exam. Whilst these enhanced courses may be excellent (and i have signed up for something along these lines) it doesn't detract from what a shambles the existing set training program really is. No manual, no exam paper and little of benefit in the fixed syllabus.

ATB

Sounds like you had a bad experience.
I did my training with IANTD so cant comment on TDIs classes

Nobody suggested you plan bailout around SCR. I would never recommend that myself and always have access to enough OC to get me up

But if the loop is intact and the scrubber working (ie lost electronics) SCR to me is prefferable to using all my OC bail gas as it will extend the bail gas I have (run the SCR off the bail gas) and give me a larger safety margin. On a deep dive where I dont want to be dragging lots of bottom bail gas around It can enable me to take the option of swimming back to the realtive safety of the upline instead of doing an imediate ascent in what can be unfriendly conditions.

The only downside is a small drop in FO2 and not breathing out every breath as you do OC - the benefits though are much lower bail gas consumption rate which gives me a higher safety margin.

Ben Field · 9th February 2006, 14:37

Quote: (Originally Posted by Drmike)

On a deep dive where I dont want to be dragging lots of bottom bail gas around It can enable me to take the option of swimming back to the realtive safety of the upline instead of doing an imediate ascent in what can be unfriendly conditions.

Ages ago, long before I got a rebreather I recall seeing online a nice spreadsheet for SCR bailout. IIRC it had "Planned drop in PPO2" across the top and "Depth" down the side. So you could choose to except a larger % drop for higher number of breaths between vent & refill of the loop or very few SCR breaths for very small changes in PPO2...

I may have got that all ar*e about face but I guess you'll know what I mean...

Anyone like to venture whether thats a good idea and if a modern equivalent exists?

Thanks,
BEN

PeteS · 9th February 2006, 17:32

Well, IMHO (me, humble?),

I did an OC trimix course. I also did a CCR trimix course. Having done the OC course, the CCR course didn't teach me anything I couldn't figure out. My IANTD course merely suceeded in generating a PIC card. An expensive peice of plastic.

As for baling out in the event of any trouble on the unit? Well what got hammered into me on my mod 1 course was "duration is on the loop". You need to learn to sort the problems out, rather than ditching the loop and going to a limited OC gas supply. You must understand what the thing on your back is doing, what screws it, and what you can do to get round it. Think your way out of trouble, not just jump to baleout.

There are times when you must get off the loop, but they are far and few between. If you stop thinking, go back to OC.

Now to answer the original question, my favourite baleout gas? None for me, but I'll carry part of team baleout if my buddies need it.

Underwaterbear · 9th February 2006, 20:52

So this is quite interesting. It seems we have two camps - one that will include SCR as a bailout mode and one that doesn't. To my way of thinking SCR is the response to a very specific issue - lost electronics. I personally know from experience diving an Azimuth and running through all the planning time and again roughly what FiO2 to expect on the bottom from any given gas. SO my response to Steve is that I could probably wing it but on a big dive and with all the stress I would much rather cut a schedule that gets me up SCR to where I can run CCR O2 again. If I have a more or less standard set of gases this is a trivial table to carry in a pocket.

Of course dead electronics is just one failure mode and there are others to consider that do not include SCR as a bailout mode...obviously the OC bailout is the simplest scenario where it is no different to OC tmx planning as pointed out...it's integrating it all where it gets tough.

What I was interested in (first post) was if people take such things into account, and if they do, what have they come up with as something that works for them.

Cheers

Nick uk. · 9th February 2006, 22:45

Quote: (Originally Posted by PeteS)

Well, IMHO (me, humble?),

I did an OC trimix course. I also did a CCR trimix course. Having done the OC course, the CCR course didn't teach me anything I couldn't figure out. My IANTD course merely suceeded in generating a PIC card. An expensive peice of plastic.

As for baling out in the event of any trouble on the unit? Well what got hammered into me on my mod 1 course was "duration is on the loop". You need to learn to sort the problems out, rather than ditching the loop and going to a limited OC gas supply. You must understand what the thing on your back is doing, what screws it, and what you can do to get round it. Think your way out of trouble, not just jump to baleout.

There are times when you must get off the loop, but they are far and few between. If you stop thinking, go back to OC.

Now to answer the original question, my favourite baleout gas? None for me, but I'll carry part of team baleout if my buddies need it.

Naah, don't agree in the slightest.

Were not in the S.A.S. you know, you Do know don't you?
It's not the 'Crypton factor', or a 'countdown conundrum', If there's a problem bail out to OC, sort it, and if possible get back on the loop!

There's no snipers looking for tell tale signs of bubbles on the surface, sheesh!
WHY WOULD YOU, even contenplate trying to sort out ANY kind of problem CC at ANY depth for ANY lengh of time, risking NOT BEING ABLE TO 'SORT' IT when you could (and IMHO should) bail out OC?
Now, i don't want to get into a slanging match, but go on, CONVINCE ME WHY!!

Nick uk. · 9th February 2006, 22:49

Quote: (Originally Posted by Underwaterbear)

So this is quite interesting. It seems we have two camps - one that will include SCR as a bailout mode and one that doesn't. To my way of thinking SCR is the response to a very specific issue - lost electronics. I personally know from experience diving an Azimuth and running through all the planning time and again roughly what FiO2 to expect on the bottom from any given gas. SO my response to Steve is that I could probably wing it but on a big dive and with all the stress I would much rather cut a schedule that gets me up SCR to where I can run CCR O2 again. If I have a more or less standard set of gases this is a trivial table to carry in a pocket.

Of course dead electronics is just one failure mode and there are others to consider that do not include SCR as a bailout mode...obviously the OC bailout is the simplest scenario where it is no different to OC tmx planning as pointed out...it's integrating it all where it gets tough.

What I was interested in (first post) was if people take such things into account, and if they do, what have they come up with as something that works for them.

Cheers

Yeah ok, but on an AZZI your first line of deffence is anyway an on-board bail out with what should be the same mix/FO2! So half the work is done for you.

If you start your dive SCR, and your bail out is SCR, there's not much of a trade off...............is there?

pchanning · 9th February 2006, 23:05

Quote: (Originally Posted by Ben Field)

Ages ago, long before I got a rebreather I recall seeing online a nice spreadsheet for SCR bailout. IIRC it had "Planned drop in PPO2" across the top and "Depth" down the side. So you could choose to except a larger % drop for higher number of breaths between vent & refill of the loop or very few SCR breaths for very small changes in PPO2...

You may referring to the 'Linear Semi-Closed Bail-Out Tables' produced, with much effort I might add, by Geraint Foulkes Jones - his method built on the work by the late Will Smithers and allowed for ascents SCR. I believe Padowan has come up with a fixed-depth spreadsheet that I am sure he will be pleased to send you - PM him.

Quote: (Originally Posted by Ben Field)

I may have got that all ar*e about face but I guess you'll know what I mean...

Anyone like to venture whether thats a good idea and if a modern equivalent exists?

Thanks,
BEN

Its all voodoo if you ask me

HTH
cheers
paul

Underwaterbear · 9th February 2006, 23:27

Quote: (Originally Posted by Nick uk.)

Yeah ok, but on an AZZI your first line of deffence is anyway an on-board bail out with what should be the same mix/FO2! So half the work is done for you.

If you start your dive SCR, and your bail out is SCR, there's not much of a trade off...............is there?

I dive a Prism these days but I was saying I'm well practised at thinking along the SCR lines ie what the FiO2 drop will be for a given gas at a given flow rate. As an aside I used to dive the Azi as a two mix unit. The deep gas was run at the flow rate of the shallow gas...so something like Nx26 and NX50 running at about 6lpm got me to 50m or thereabouts. Bailout for that was Air and the on board stuff.

Nick uk. · 9th February 2006, 23:31

Quote: (Originally Posted by Underwaterbear)

I dive a Prism these days but I was saying I'm well practised at thinking along the SCR lines ie what the FiO2 drop will be for a given gas at a given flow rate. As an aside I used to dive the Azi as a two mix unit. The deep gas was run at the flow rate of the shallow gas...so something like Nx26 and NX50 running at about 6lpm got me to 50m or thereabouts. Bailout for that was Air and the on board stuff.

OK, but it's crunch time.................bail out, OC or SCR? and your time starts.......NOW!

Drmike · 10th February 2006, 04:10

Quote: (Originally Posted by Nick uk.)

WHY WOULD YOU, even contenplate trying to sort out ANY kind of problem CC at ANY depth for ANY lengh of time, risking NOT BEING ABLE TO 'SORT' IT when you could (and IMHO should) bail out OC?
Now, i don't want to get into a slanging match, but go on, CONVINCE ME WHY!!

When faced with a problem underwater a smart diver will evaluate all his options look at the balance of risks for his particular current situation and chose the best solution out of those available to him.

There are times such as on a deep dive, long penetration etc when the potential risk of running out of bottom OC bail gas after bailing is higher (you could get lost inside wreck after bailing, loose the cave line after bailing, need to swim to upline, lost buddy, take longer than you planned to get out of the overhead, your RMV could be much higher than you planned for etc)

The fact you are deep means the balance of risk is shifted the safety margin on OC consumption is smaller. In these cases a diver might decide to extend the bottom OC bail gas by running it SCR. The only downside is small drop in FO2 - but if your bail gas is selected with a high enough FO2 you could end up with a reasonable or even the same effective ppo2 at depth as you were running as a setpoint anyway.

9th February 2006, 14:11	#21 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,165	Re: Favourite bailout gases Quote: (Originally Posted by Mark Chase) Personally I have done the Mod3 trimix CCR course but it didn't teach me anything new that would help with this question. Im my mind any sort of bailout plan that involves using the CCR is unacceptable. Bailout plans for me are OC based. Anything else is semi Alpinist. I didn't need a CCR based training to let me figure out an OC decompression form X depth and then include a suitable travel gas to get from depth to deco mix. Personally I think the fixed syllabus TDI trimix training for Mod3 is rubbish. There are instructors out there who are writing their own syllabus and in one case i am aware of he is writing a proper CCR based exam. Whilst these enhanced courses may be excellent (and i have signed up for something along these lines) it doesn't detract from what a shambles the existing set training program really is. No manual, no exam paper and little of benefit in the fixed syllabus. ATB Sounds like you had a bad experience. I did my training with IANTD so cant comment on TDIs classes Nobody suggested you plan bailout around SCR. I would never recommend that myself and always have access to enough OC to get me up But if the loop is intact and the scrubber working (ie lost electronics) SCR to me is prefferable to using all my OC bail gas as it will extend the bail gas I have (run the SCR off the bail gas) and give me a larger safety margin. On a deep dive where I dont want to be dragging lots of bottom bail gas around It can enable me to take the option of swimming back to the realtive safety of the upline instead of doing an imediate ascent in what can be unfriendly conditions. The only downside is a small drop in FO2 and not breathing out every breath as you do OC - the benefits though are much lower bail gas consumption rate which gives me a higher safety margin. __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment Last edited by Drmike : 9th February 2006 at 14:15.
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9th February 2006, 14:37	#22 (permalink)
Ben Field CK+Shearwater Current Rebreather/s: Classic Kiss Other Rebreather/s: Sport Kiss Join Date: Aug 2005 Location: London, England Posts: 1,571	Re: Favourite bailout gases Quote: (Originally Posted by Drmike) On a deep dive where I dont want to be dragging lots of bottom bail gas around It can enable me to take the option of swimming back to the realtive safety of the upline instead of doing an imediate ascent in what can be unfriendly conditions. Ages ago, long before I got a rebreather I recall seeing online a nice spreadsheet for SCR bailout. IIRC it had "Planned drop in PPO2" across the top and "Depth" down the side. So you could choose to except a larger % drop for higher number of breaths between vent & refill of the loop or very few SCR breaths for very small changes in PPO2... I may have got that all are about face but I guess you'll know what I mean... Anyone like to venture whether thats a good idea and if a modern equivalent exists? Thanks, BEN __________________ www.hugsac.org.uk Beware Fridge Suck*
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9th February 2006, 17:32	#23 (permalink)
PeteS Consent Issued! Current Rebreather/s: Inspiration Classic Inspiration Vision Other Rebreather/s: Join Date: Jun 2005 Location: New Zealand Posts: 515	Re: Favourite bailout gases Well, IMHO (me, humble?), I did an OC trimix course. I also did a CCR trimix course. Having done the OC course, the CCR course didn't teach me anything I couldn't figure out. My IANTD course merely suceeded in generating a PIC card. An expensive peice of plastic. As for baling out in the event of any trouble on the unit? Well what got hammered into me on my mod 1 course was "duration is on the loop". You need to learn to sort the problems out, rather than ditching the loop and going to a limited OC gas supply. You must understand what the thing on your back is doing, what screws it, and what you can do to get round it. Think your way out of trouble, not just jump to baleout. There are times when you must get off the loop, but they are far and few between. If you stop thinking, go back to OC. Now to answer the original question, my favourite baleout gas? None for me, but I'll carry part of team baleout if my buddies need it. __________________ Pete S. http://www.steggle.co.nz Every silver lining has a cloud
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9th February 2006, 20:52	#24 (permalink)
Underwaterbear A Prismer in Megland Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2005 Location: Seattle, WA Posts: 185	Re: Favourite bailout gases So this is quite interesting. It seems we have two camps - one that will include SCR as a bailout mode and one that doesn't. To my way of thinking SCR is the response to a very specific issue - lost electronics. I personally know from experience diving an Azimuth and running through all the planning time and again roughly what FiO2 to expect on the bottom from any given gas. SO my response to Steve is that I could probably wing it but on a big dive and with all the stress I would much rather cut a schedule that gets me up SCR to where I can run CCR O2 again. If I have a more or less standard set of gases this is a trivial table to carry in a pocket. Of course dead electronics is just one failure mode and there are others to consider that do not include SCR as a bailout mode...obviously the OC bailout is the simplest scenario where it is no different to OC tmx planning as pointed out...it's integrating it all where it gets tough. What I was interested in (first post) was if people take such things into account, and if they do, what have they come up with as something that works for them. Cheers
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9th February 2006, 22:45	#25 (permalink)
Nick uk. Made in England. Current Rebreather/s: Inspiration Classic Azimuth Other Rebreather/s: Azimuth Join Date: Nov 2005 Location: Viale C.Colombo 75 Marina di Carrara. MS 54036 Italy Posts: 579	Re: Favourite bailout gases Quote: (Originally Posted by PeteS) Well, IMHO (me, humble?), I did an OC trimix course. I also did a CCR trimix course. Having done the OC course, the CCR course didn't teach me anything I couldn't figure out. My IANTD course merely suceeded in generating a PIC card. An expensive peice of plastic. As for baling out in the event of any trouble on the unit? Well what got hammered into me on my mod 1 course was "duration is on the loop". You need to learn to sort the problems out, rather than ditching the loop and going to a limited OC gas supply. You must understand what the thing on your back is doing, what screws it, and what you can do to get round it. Think your way out of trouble, not just jump to baleout. There are times when you must get off the loop, but they are far and few between. If you stop thinking, go back to OC. Now to answer the original question, my favourite baleout gas? None for me, but I'll carry part of team baleout if my buddies need it. Naah, don't agree in the slightest. Were not in the S.A.S. you know, you Do know don't you? It's not the 'Crypton factor', or a 'countdown conundrum', If there's a problem bail out to OC, sort it, and if possible get back on the loop! There's no snipers looking for tell tale signs of bubbles on the surface, sheesh! WHY WOULD YOU, even contenplate trying to sort out ANY kind of problem CC at ANY depth for ANY lengh of time, risking NOT BEING ABLE TO 'SORT' IT when you could (and IMHO should) bail out OC? Now, i don't want to get into a slanging match, but go on, CONVINCE ME WHY!! __________________ If it aint broke....don't fix it, and if it is.............well......get another one! divechief2000@hotmail.com
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9th February 2006, 22:49	#26 (permalink)
Nick uk. Made in England. Current Rebreather/s: Inspiration Classic Azimuth Other Rebreather/s: Azimuth Join Date: Nov 2005 Location: Viale C.Colombo 75 Marina di Carrara. MS 54036 Italy Posts: 579	Re: Favourite bailout gases Quote: (Originally Posted by Underwaterbear) So this is quite interesting. It seems we have two camps - one that will include SCR as a bailout mode and one that doesn't. To my way of thinking SCR is the response to a very specific issue - lost electronics. I personally know from experience diving an Azimuth and running through all the planning time and again roughly what FiO2 to expect on the bottom from any given gas. SO my response to Steve is that I could probably wing it but on a big dive and with all the stress I would much rather cut a schedule that gets me up SCR to where I can run CCR O2 again. If I have a more or less standard set of gases this is a trivial table to carry in a pocket. Of course dead electronics is just one failure mode and there are others to consider that do not include SCR as a bailout mode...obviously the OC bailout is the simplest scenario where it is no different to OC tmx planning as pointed out...it's integrating it all where it gets tough. What I was interested in (first post) was if people take such things into account, and if they do, what have they come up with as something that works for them. Cheers Yeah ok, but on an AZZI your first line of deffence is anyway an on-board bail out with what should be the same mix/FO2! So half the work is done for you. If you start your dive SCR, and your bail out is SCR, there's not much of a trade off...............is there? __________________ If it aint broke....don't fix it, and if it is.............well......get another one! divechief2000@hotmail.com
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9th February 2006, 23:05	#27 (permalink)
pchanning PFO free :) Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: fixed! Posts: 454	Re: Favourite bailout gases Quote: (Originally Posted by Ben Field) Ages ago, long before I got a rebreather I recall seeing online a nice spreadsheet for SCR bailout. IIRC it had "Planned drop in PPO2" across the top and "Depth" down the side. So you could choose to except a larger % drop for higher number of breaths between vent & refill of the loop or very few SCR breaths for very small changes in PPO2... You may referring to the 'Linear Semi-Closed Bail-Out Tables' produced, with much effort I might add, by Geraint Foulkes Jones - his method built on the work by the late Will Smithers and allowed for ascents SCR. I believe Padowan has come up with a fixed-depth spreadsheet that I am sure he will be pleased to send you - PM him. Quote: (Originally Posted by Ben Field) I may have got that all are about face but I guess you'll know what I mean... Anyone like to venture whether thats a good idea and if a modern equivalent exists? Thanks, BEN Its all voodoo if you ask me HTH cheers paul __________________ Cheers Paul The key to enlightenment... is survival.*
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9th February 2006, 23:27	#28 (permalink)
Underwaterbear A Prismer in Megland Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2005 Location: Seattle, WA Posts: 185	Re: Favourite bailout gases Quote: (Originally Posted by Nick uk.) Yeah ok, but on an AZZI your first line of deffence is anyway an on-board bail out with what should be the same mix/FO2! So half the work is done for you. If you start your dive SCR, and your bail out is SCR, there's not much of a trade off...............is there? I dive a Prism these days but I was saying I'm well practised at thinking along the SCR lines ie what the FiO2 drop will be for a given gas at a given flow rate. As an aside I used to dive the Azi as a two mix unit. The deep gas was run at the flow rate of the shallow gas...so something like Nx26 and NX50 running at about 6lpm got me to 50m or thereabouts. Bailout for that was Air and the on board stuff.
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9th February 2006, 23:31	#29 (permalink)
Nick uk. Made in England. Current Rebreather/s: Inspiration Classic Azimuth Other Rebreather/s: Azimuth Join Date: Nov 2005 Location: Viale C.Colombo 75 Marina di Carrara. MS 54036 Italy Posts: 579	Re: Favourite bailout gases Quote: (Originally Posted by Underwaterbear) I dive a Prism these days but I was saying I'm well practised at thinking along the SCR lines ie what the FiO2 drop will be for a given gas at a given flow rate. As an aside I used to dive the Azi as a two mix unit. The deep gas was run at the flow rate of the shallow gas...so something like Nx26 and NX50 running at about 6lpm got me to 50m or thereabouts. Bailout for that was Air and the on board stuff. OK, but it's crunch time.................bail out, OC or SCR? and your time starts.......NOW! __________________ If it aint broke....don't fix it, and if it is.............well......get another one! divechief2000@hotmail.com
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10th February 2006, 04:10	#30 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,165	Re: Favourite bailout gases Quote: (Originally Posted by Nick uk.) WHY WOULD YOU, even contenplate trying to sort out ANY kind of problem CC at ANY depth for ANY lengh of time, risking NOT BEING ABLE TO 'SORT' IT when you could (and IMHO should) bail out OC? Now, i don't want to get into a slanging match, but go on, CONVINCE ME WHY!! When faced with a problem underwater a smart diver will evaluate all his options look at the balance of risks for his particular current situation and chose the best solution out of those available to him. There are times such as on a deep dive, long penetration etc when the potential risk of running out of bottom OC bail gas after bailing is higher (you could get lost inside wreck after bailing, loose the cave line after bailing, need to swim to upline, lost buddy, take longer than you planned to get out of the overhead, your RMV could be much higher than you planned for etc) The fact you are deep means the balance of risk is shifted the safety margin on OC consumption is smaller. In these cases a diver might decide to extend the bottom OC bail gas by running it SCR. The only downside is small drop in FO2 - but if your bail gas is selected with a high enough FO2 you could end up with a reasonable or even the same effective ppo2 at depth as you were running as a setpoint anyway. __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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