Which bailout gas?

Abbo · 5th July 2008, 05:05

What dil and bailout would you use for dives to 60, 80, 100, 120m?
Is the dil always the same as the bail out?
Why did you make the decisions that you made?
Some people would violently disagree about your choices: what are their arguments, and how would you reply to their arguments?
Do any of the following diving conditions cause you to change your dil & bailout: High current, whether at the surface or at depth; Low temperatures, causing you to want to get out of the water as soon as possible; Conditions where, because of a tight squeeze or low visibility, you might be unable to check your gauges.

The background to this question is the "Reading Material For Mixed Gas CCR" thread. These are some of the questions I would like a good mixed gas textbook to cover.
http://www.rebreatherworld.com/o2pti...gas-ccr-3.html

tecdivertraining · 5th July 2008, 06:55

Quote: (Originally Posted by Abbo)

What dil and bailout would you use for dives to 60, 80, 100, 120m?
Is the dil always the same as the bail out?
Why did you make the decisions that you made?
Some people would violently disagree about your choices: what are their arguments, and how would you reply to their arguments?
Do any of the following diving conditions cause you to change your dil & bailout: High current, whether at the surface or at depth; Low temperatures, causing you to want to get out of the water as soon as possible; Conditions where, because of a tight squeeze or low visibility, you might be unable to check your gauges.

The background to this question is the "Reading Material For Mixed Gas CCR" thread. These are some of the questions I would like a good mixed gas textbook to cover.
http://www.rebreatherworld.com/o2pti...gas-ccr-3.html

Hi buddy,

Just to get your thread started I would use the following:

60m dive – on-board gas 17/30
off-board gas – deep bail gas same as on-board (KISS)
Then to a 50% (fix those bloody bubbles)

80-120m - on-board gas 10/55 (easy cell checks, easy to mix, good END)

off-board gas – deep bail gas same as on-board (KISS)
Then to a 32/20 (ICD) and 50 & O2 (fix those bloody bubbles)

None of your following environmental changes would cause me to select differing gases but support divers, spare gas, trapezes and staged shallow bail would need consideration.

I new their was a reason you should do a mix course with me!!!

Lancer4545 · 5th July 2008, 08:58

Quote: (Originally Posted by tecdivertraining)

I new their was a reason you should do a mix course with me!!!

I agree!!!

If you don't understand what's happening don't try it without doing the course!!!

Matt will teach you everything you need to know and then more....and you might even have a bit of fun doing it too

Regards,

Lance

Abbo · 5th July 2008, 09:02

Quote: (Originally Posted by tecdivertraining)

I knew there was a reason you should do a mix course with me!!!

Thanks for that.

In CCR trimix I was taught to pick a bailout gas with a PO2 of 2.0 at the maximum depth of the dive. The logic was as follows: as a rule of thumb, the first decompression stop is at half the depth of the maximum depth. Time at the bottom is small compared with the total run time, so the probability of a problem requiring bailout while at the maximum depth is proportionally smaller. Swim up from the maximum depth to the first decompression stop. As you do so your PO2 will be falling. Most people can tolerate a PO2 of 2.0 for a few minutes at least while they swim up to their first deco stop. The high PO2 of the bailout gas will make the decompression shorter, obviating the need for carrying large amounts of bailout gas. The main trouble in bailout is the difficulty of carrying enough gas on your own for the whole decompression.

The trouble with this strategy, I felt, is that a hypercapnia hit is the most likely cause of my coming off the loop. The hypercapnia would hugely increase the risk of an ox tox hit. I wouldn't use this strategy, but I am still very interested in how people get round the problem of carrying enough gas on deeper dives. I am not comfortable with the idea of team bailout.

Had it been possible, I would certainly have done my mix course with you! I look forward to seeing you later this month.

si_b_lanzarote · 5th July 2008, 09:31

Quote: (Originally Posted by Abbo)

Thanks for that.

In CCR trimix I was taught to pick a bailout gas with a PO2 of 2.0 at the maximum depth of the dive. The logic was as follows: as a rule of thumb, the first decompression stop is at half the depth of the maximum depth. Time at the bottom is small compared with the total run time, so the probability of a problem requiring bailout while at the maximum depth is proportionally smaller. Swim up from the maximum depth to the first decompression stop. As you do so your PO2 will be falling. Most people can tolerate a PO2 of 2.0 for a few minutes at least while they swim up to their first deco stop. The high PO2 of the bailout gas will make the decompression shorter, obviating the need for carrying large amounts of bailout gas. The main trouble in bailout is the difficulty of carrying enough gas on your own for the whole decompression.

The trouble with this strategy, I felt, is that a hypercapnia hit is the most likely cause of my coming off the loop. The hypercapnia would hugely increase the risk of an ox tox hit. I wouldn't use this strategy, but I am still very interested in how people get round the problem of carrying enough gas on deeper dives. I am not comfortable with the idea of team bailout.

Had it been possible, I would certainly have done my mix course with you! I look forward to seeing you later this month.

hi Abbo

ive had a look at your profile and see you have IANTD PSAI and TDI certs, which one is your CCR TMX with? i am curious which agency allows this practice??? two of them i am very familiar with and know they dont permit this practice.

regards si

tecdivertraining · 5th July 2008, 09:32

Quote: (Originally Posted by Abbo)

Thanks for that.

In CCR trimix I was taught to pick a bailout gas with a PO2 of 2.0 at the maximum depth of the dive. The logic was as follows: as a rule of thumb, the first decompression stop is at half the depth of the maximum depth. Time at the bottom is small compared with the total run time, so the probability of a problem requiring bailout while at the maximum depth is proportionally smaller. Swim up from the maximum depth to the first decompression stop. As you do so your PO2 will be falling. Most people can tolerate a PO2 of 2.0 for a few minutes at least while they swim up to their first deco stop. The high PO2 of the bailout gas will make the decompression shorter, obviating the need for carrying large amounts of bailout gas. The main trouble in bailout is the difficulty of carrying enough gas on your own for the whole decompression.Had it been possible, I would certainly have done my mix course with you! I look forward to seeing you later this month.

We spoke a while back about this and in theory it could work but I would not like to try having had a Co2 issue, or even just the added stress at that point of the dive. yes we have done ppo2 deco at 2.8 without issues in a dry environment but I would not play roulette if its not necessary, if gas volume is an issue carry two bottom mix stages and intermediates/deco on the but pad 4 stages is easy and your twice my size

.

looking forward to catching up, have 4 diving megs when your here so should be fun.

tecdivertraining · 5th July 2008, 09:33

Quote: (Originally Posted by si_b_lanzarote)

hi Abbo

ive had a look at your profile and see you have IANTD PSAI and TDI certs, which one is your CCR TMX with? i am curious which agency allows this practice??? two of them i am very familiar with and know they dont permit this practice.

regards si

Your quite right no agency allows this, thats a separate issue.

Mark Chase · 5th July 2008, 09:46

Quote: (Originally Posted by Abbo)

What dil and bailout would you use for dives to 60, 80, 100, 120m?
Is the dil always the same as the bail out?
Why did you make the decisions that you made?
Some people would violently disagree about your choices: what are their arguments, and how would you reply to their arguments?
Do any of the following diving conditions cause you to change your dil & bailout: High current, whether at the surface or at depth; Low temperatures, causing you to want to get out of the water as soon as possible; Conditions where, because of a tight squeeze or low visibility, you might be unable to check your gauges.

The background to this question is the "Reading Material For Mixed Gas CCR" thread. These are some of the questions I would like a good mixed gas textbook to cover.
http://www.rebreatherworld.com/o2pti...gas-ccr-3.html

I use 18/45 and 50% down to 75m with a 10ltr drop tank of 80% on the boat. Deeper Ill add a 10 of 13/60 down to 100 or 10/70 to 120 and Ill swap the 10ltr of 18/45 for a 7ltr of 18/45 and run two 10s and a 7 + the drop tank.

ATB

Mark

Mark Chase · 5th July 2008, 09:54

Quote: (Originally Posted by si_b_lanzarote)

hi Abbo

ive had a look at your profile and see you have IANTD PSAI and TDI certs, which one is your CCR TMX with? i am curious which agency allows this practice??? two of them i am very familiar with and know they dont permit this practice.

regards si

TDI Trimix shows emergency exposure tables for a PP of 2.0. Obviously they stress the 1.4 max on the bottom but by including the emergency exposure tables are they not suggesting that it could be used in an emergency?

I used to plan first deco mix max 2.0 on the bottom for OC dives so i could bail on to deco mix if i had to . I never did.

On CCR I have spiked well over 2 on the bottom. When my Hammer Head decided to try and kill me I hit a PPo2 of 2.5 several times before I was able to get it under control and that was from 65m and up.

I believe if your not panicked by it and are basically resting its not the end of the world hitting 2.0 for a min or two. However the question is should we plan for it?

Since discovering (thanks to divers on this site) that high PP02 and C02 hits are a bad combination i have limited my deep bailout to 1.4. down from a previously planned 1.6

ATB

Mark

si_b_lanzarote · 5th July 2008, 11:07

Quote: (Originally Posted by Mark Chase)

TDI Trimix shows emergency exposure tables for a PP of 2.0. Obviously they stress the 1.4 max on the bottom but by including the emergency exposure tables are they not suggesting that it could be used in an emergency?

I used to plan first deco mix max 2.0 on the bottom for OC dives so i could bail on to deco mix if i had to . I never did.

On CCR I have spiked well over 2 on the bottom. When my Hammer Head decided to try and kill me I hit a PPo2 of 2.5 several times before I was able to get it under control and that was from 65m and up.

I believe if your not panicked by it and are basically resting its not the end of the world hitting 2.0 for a min or two. However the question is should we plan for it?

Since discovering (thanks to divers on this site) that high PP02 and C02 hits are a bad combination i have limited my deep bailout to 1.4. down from a previously planned 1.6

ATB

Mark

my extended range manual has buehlmann tables to 60m but it doesnt mean they are sanctioning 60m air dives, the cert is clearly 55m.
i think you will find the emergency exposure tables are in the same vein as the ouroboros allowing 2.0 bar ppo2 it is for emergency therapeutic reasons not for actual diving.

as for the ppo2 question i agree its not the end of the world, and to be honest high o2 is not the scary one for me its the low o2 that i would be more concerned with, but in view of other threads going on at the moment regarding alignment of manufacturers and agencies, it doesnt help our defence as instructors when some instructors are teaching these sort of practices.

regards si

5th July 2008, 05:05	#1 (permalink)
Abbo Nicholas Smith Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 440	Which bailout gas? What dil and bailout would you use for dives to 60, 80, 100, 120m? Is the dil always the same as the bail out? Why did you make the decisions that you made? Some people would violently disagree about your choices: what are their arguments, and how would you reply to their arguments? Do any of the following diving conditions cause you to change your dil & bailout: High current, whether at the surface or at depth; Low temperatures, causing you to want to get out of the water as soon as possible; Conditions where, because of a tight squeeze or low visibility, you might be unable to check your gauges. The background to this question is the "Reading Material For Mixed Gas CCR" thread. These are some of the questions I would like a good mixed gas textbook to cover. http://www.rebreatherworld.com/o2pti...gas-ccr-3.html
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5th July 2008, 06:55	#2 (permalink)
tecdivertraining RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon Ouroboros Dolphin Other Rebreather/s: Not Bought Yet Dolphin Join Date: May 2005 Location: Phuket, Thailand Posts: 462	Re: Which bailout gas? Quote: (Originally Posted by Abbo) What dil and bailout would you use for dives to 60, 80, 100, 120m? Is the dil always the same as the bail out? Why did you make the decisions that you made? Some people would violently disagree about your choices: what are their arguments, and how would you reply to their arguments? Do any of the following diving conditions cause you to change your dil & bailout: High current, whether at the surface or at depth; Low temperatures, causing you to want to get out of the water as soon as possible; Conditions where, because of a tight squeeze or low visibility, you might be unable to check your gauges. The background to this question is the "Reading Material For Mixed Gas CCR" thread. These are some of the questions I would like a good mixed gas textbook to cover. http://www.rebreatherworld.com/o2pti...gas-ccr-3.html Hi buddy, Just to get your thread started I would use the following: 60m dive – on-board gas 17/30 off-board gas – deep bail gas same as on-board (KISS) Then to a 50% (fix those bloody bubbles) 80-120m - on-board gas 10/55 (easy cell checks, easy to mix, good END) off-board gas – deep bail gas same as on-board (KISS) Then to a 32/20 (ICD) and 50 & O2 (fix those bloody bubbles) None of your following environmental changes would cause me to select differing gases but support divers, spare gas, trapezes and staged shallow bail would need consideration. I new their was a reason you should do a mix course with me!!! __________________ Mathew Partridge Technical Director Pro-Tech Dive College www.protechdivers.com www.tech-ccr.com
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5th July 2008, 08:58	#3 (permalink)
Lancer4545 Closed Circuit Divers Aus Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2007 Location: Cairns QLD Australia Posts: 664	Re: Which bailout gas? Quote: (Originally Posted by tecdivertraining) I new their was a reason you should do a mix course with me!!! I agree!!! If you don't understand what's happening don't try it without doing the course!!! Matt will teach you everything you need to know and then more....and you might even have a bit of fun doing it too Regards, Lance __________________ You can run but you can't hide! ISC Appointed Megalodon Dealer for East Australia http://www.closedcircuitdivers.com.au info@closedcircuitdivers.com.au
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5th July 2008, 09:02	#4 (permalink)
Abbo Nicholas Smith Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 440	Re: Which bailout gas? Quote: (Originally Posted by tecdivertraining) I knew there was a reason you should do a mix course with me!!! Thanks for that. In CCR trimix I was taught to pick a bailout gas with a PO2 of 2.0 at the maximum depth of the dive. The logic was as follows: as a rule of thumb, the first decompression stop is at half the depth of the maximum depth. Time at the bottom is small compared with the total run time, so the probability of a problem requiring bailout while at the maximum depth is proportionally smaller. Swim up from the maximum depth to the first decompression stop. As you do so your PO2 will be falling. Most people can tolerate a PO2 of 2.0 for a few minutes at least while they swim up to their first deco stop. The high PO2 of the bailout gas will make the decompression shorter, obviating the need for carrying large amounts of bailout gas. The main trouble in bailout is the difficulty of carrying enough gas on your own for the whole decompression. The trouble with this strategy, I felt, is that a hypercapnia hit is the most likely cause of my coming off the loop. The hypercapnia would hugely increase the risk of an ox tox hit. I wouldn't use this strategy, but I am still very interested in how people get round the problem of carrying enough gas on deeper dives. I am not comfortable with the idea of team bailout. Had it been possible, I would certainly have done my mix course with you! I look forward to seeing you later this month.
(Offline)

5th July 2008, 09:31	#5 (permalink)
si_b_lanzarote New Member Current Rebreather/s: Inspiration Classic Inspiration Vision Megalodon Ouroboros Other CCR Dolphin Ray Home Build Other Rebreather/s: Other CCR Dolphin Ray Home Build Join Date: Dec 2006 Location: lanzarote, Canary Islands Posts: 88	Re: Which bailout gas? Quote: (Originally Posted by Abbo) Thanks for that. In CCR trimix I was taught to pick a bailout gas with a PO2 of 2.0 at the maximum depth of the dive. The logic was as follows: as a rule of thumb, the first decompression stop is at half the depth of the maximum depth. Time at the bottom is small compared with the total run time, so the probability of a problem requiring bailout while at the maximum depth is proportionally smaller. Swim up from the maximum depth to the first decompression stop. As you do so your PO2 will be falling. Most people can tolerate a PO2 of 2.0 for a few minutes at least while they swim up to their first deco stop. The high PO2 of the bailout gas will make the decompression shorter, obviating the need for carrying large amounts of bailout gas. The main trouble in bailout is the difficulty of carrying enough gas on your own for the whole decompression. The trouble with this strategy, I felt, is that a hypercapnia hit is the most likely cause of my coming off the loop. The hypercapnia would hugely increase the risk of an ox tox hit. I wouldn't use this strategy, but I am still very interested in how people get round the problem of carrying enough gas on deeper dives. I am not comfortable with the idea of team bailout. Had it been possible, I would certainly have done my mix course with you! I look forward to seeing you later this month. hi Abbo ive had a look at your profile and see you have IANTD PSAI and TDI certs, which one is your CCR TMX with? i am curious which agency allows this practice??? two of them i am very familiar with and know they dont permit this practice. regards si __________________ http://www.thediveshoplanzarote.com
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5th July 2008, 09:32	#6 (permalink)
tecdivertraining RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon Ouroboros Dolphin Other Rebreather/s: Not Bought Yet Dolphin Join Date: May 2005 Location: Phuket, Thailand Posts: 462	Re: Which bailout gas? Quote: (Originally Posted by Abbo) Thanks for that. In CCR trimix I was taught to pick a bailout gas with a PO2 of 2.0 at the maximum depth of the dive. The logic was as follows: as a rule of thumb, the first decompression stop is at half the depth of the maximum depth. Time at the bottom is small compared with the total run time, so the probability of a problem requiring bailout while at the maximum depth is proportionally smaller. Swim up from the maximum depth to the first decompression stop. As you do so your PO2 will be falling. Most people can tolerate a PO2 of 2.0 for a few minutes at least while they swim up to their first deco stop. The high PO2 of the bailout gas will make the decompression shorter, obviating the need for carrying large amounts of bailout gas. The main trouble in bailout is the difficulty of carrying enough gas on your own for the whole decompression.Had it been possible, I would certainly have done my mix course with you! I look forward to seeing you later this month. We spoke a while back about this and in theory it could work but I would not like to try having had a Co2 issue, or even just the added stress at that point of the dive. yes we have done ppo2 deco at 2.8 without issues in a dry environment but I would not play roulette if its not necessary, if gas volume is an issue carry two bottom mix stages and intermediates/deco on the but pad 4 stages is easy and your twice my size. looking forward to catching up, have 4 diving megs when your here so should be fun. __________________ Mathew Partridge Technical Director Pro-Tech Dive College www.protechdivers.com www.tech-ccr.com
(Offline)

5th July 2008, 09:33	#7 (permalink)
tecdivertraining RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon Ouroboros Dolphin Other Rebreather/s: Not Bought Yet Dolphin Join Date: May 2005 Location: Phuket, Thailand Posts: 462	Re: Which bailout gas? Quote: (Originally Posted by si_b_lanzarote) hi Abbo ive had a look at your profile and see you have IANTD PSAI and TDI certs, which one is your CCR TMX with? i am curious which agency allows this practice??? two of them i am very familiar with and know they dont permit this practice. regards si Your quite right no agency allows this, thats a separate issue. __________________ Mathew Partridge Technical Director Pro-Tech Dive College www.protechdivers.com www.tech-ccr.com
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5th July 2008, 09:46	#8 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,699	Re: Which bailout gas? Quote: (Originally Posted by Abbo) What dil and bailout would you use for dives to 60, 80, 100, 120m? Is the dil always the same as the bail out? Why did you make the decisions that you made? Some people would violently disagree about your choices: what are their arguments, and how would you reply to their arguments? Do any of the following diving conditions cause you to change your dil & bailout: High current, whether at the surface or at depth; Low temperatures, causing you to want to get out of the water as soon as possible; Conditions where, because of a tight squeeze or low visibility, you might be unable to check your gauges. The background to this question is the "Reading Material For Mixed Gas CCR" thread. These are some of the questions I would like a good mixed gas textbook to cover. http://www.rebreatherworld.com/o2pti...gas-ccr-3.html I use 18/45 and 50% down to 75m with a 10ltr drop tank of 80% on the boat. Deeper Ill add a 10 of 13/60 down to 100 or 10/70 to 120 and Ill swap the 10ltr of 18/45 for a 7ltr of 18/45 and run two 10s and a 7 + the drop tank. ATB Mark __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
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5th July 2008, 09:54	#9 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,699	Re: Which bailout gas? Quote: (Originally Posted by si_b_lanzarote) hi Abbo ive had a look at your profile and see you have IANTD PSAI and TDI certs, which one is your CCR TMX with? i am curious which agency allows this practice??? two of them i am very familiar with and know they dont permit this practice. regards si TDI Trimix shows emergency exposure tables for a PP of 2.0. Obviously they stress the 1.4 max on the bottom but by including the emergency exposure tables are they not suggesting that it could be used in an emergency? I used to plan first deco mix max 2.0 on the bottom for OC dives so i could bail on to deco mix if i had to . I never did. On CCR I have spiked well over 2 on the bottom. When my Hammer Head decided to try and kill me I hit a PPo2 of 2.5 several times before I was able to get it under control and that was from 65m and up. I believe if your not panicked by it and are basically resting its not the end of the world hitting 2.0 for a min or two. However the question is should we plan for it? Since discovering (thanks to divers on this site) that high PP02 and C02 hits are a bad combination i have limited my deep bailout to 1.4. down from a previously planned 1.6 ATB Mark __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
(Offline)

5th July 2008, 11:07	#10 (permalink)
si_b_lanzarote New Member Current Rebreather/s: Inspiration Classic Inspiration Vision Megalodon Ouroboros Other CCR Dolphin Ray Home Build Other Rebreather/s: Other CCR Dolphin Ray Home Build Join Date: Dec 2006 Location: lanzarote, Canary Islands Posts: 88	Re: Which bailout gas? Quote: (Originally Posted by Mark Chase) TDI Trimix shows emergency exposure tables for a PP of 2.0. Obviously they stress the 1.4 max on the bottom but by including the emergency exposure tables are they not suggesting that it could be used in an emergency? I used to plan first deco mix max 2.0 on the bottom for OC dives so i could bail on to deco mix if i had to . I never did. On CCR I have spiked well over 2 on the bottom. When my Hammer Head decided to try and kill me I hit a PPo2 of 2.5 several times before I was able to get it under control and that was from 65m and up. I believe if your not panicked by it and are basically resting its not the end of the world hitting 2.0 for a min or two. However the question is should we plan for it? Since discovering (thanks to divers on this site) that high PP02 and C02 hits are a bad combination i have limited my deep bailout to 1.4. down from a previously planned 1.6 ATB Mark my extended range manual has buehlmann tables to 60m but it doesnt mean they are sanctioning 60m air dives, the cert is clearly 55m. i think you will find the emergency exposure tables are in the same vein as the ouroboros allowing 2.0 bar ppo2 it is for emergency therapeutic reasons not for actual diving. as for the ppo2 question i agree its not the end of the world, and to be honest high o2 is not the scary one for me its the low o2 that i would be more concerned with, but in view of other threads going on at the moment regarding alignment of manufacturers and agencies, it doesnt help our defence as instructors when some instructors are teaching these sort of practices. regards si __________________ http://www.thediveshoplanzarote.com Last edited by si_b_lanzarote : 5th July 2008 at 11:18.
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