Backgas or Deco mix break?

indeep · September 20th, 2006, 10:44 PM

Hello all,

What are most of you doing as far as 02 breaks from 6m?
Let's say you have 20 minutes of deco at 6m.......do most of you take a break?......or will you stay on for the entire 20 minutes?

And....do you do your break on backgas?.....or onto your 50%?

Thanks in advance.

nadwidny · September 20th, 2006, 10:56 PM

Quote: (Originally Posted by indeep)

Hello all,

What are most of you doing as far as 02 breaks from 6m?
Let's say you have 20 minutes of deco at 6m.......do most of you take a break?......or will you stay on for the entire 20 minutes?

And....do you do your break on backgas?.....or onto your 50%?

Sometimes take a break. Always on backgas.

indeep · September 21st, 2006, 12:41 AM

Quote: (Originally Posted by nadwidny)

Sometimes take a break. Always on backgas.

To your response:

1) Sometimes?......state why or why not.

2) Always backgas?......state why.

ppo2_diver · September 21st, 2006, 01:58 AM

For every 12 minutes on O2, I do 6 minutes on back gas. This is assuming that my back gas is breathable at 20 feet. Since I'm not certified for anything deeper than 200 feet, I only use 18/45. So no worries there. I do breaks on back gas to reduce the O2 exposure as much as possible.

nadwidny · September 21st, 2006, 03:04 AM

Quote: (Originally Posted by indeep)

To your response:

1) Sometimes?......state why or why not.

2) Always backgas?......state why.

1. Because sometimes I want to and sometimes I don't

2. To drop the PO2 as low as possible. It's supposed to be a break from high PO2s so there is no sense doing it half-assed.

DRE · September 21st, 2006, 04:17 AM

Quote: (Originally Posted by indeep)

Hello all,

What are most of you doing as far as 02 breaks from 6m?
Let's say you have 20 minutes of deco at 6m.......do most of you take a break?......or will you stay on for the entire 20 minutes?

And....do you do your break on backgas?.....or onto your 50%?

Thanks in advance.

Anything over 20 minutes I'd definitely break; up to 20 minutes will depend on how I feel.

Michael-Fisch · September 21st, 2006, 09:14 AM

If I'm at or over 1.6pp O2 for over 30 minutes, I do breaks on a gas lower than 0.5pp O2 using the 12/6 ratio. Up to 30 minutes I don't bother, since I don't see the advantage with short O2 exposures.

Michael

*Clare Gledhill* · September 21st, 2006, 09:37 AM

This is something I have been thinking about quite a bit.

GUE teach 12 minutes on maximum. If you are then going to ascend then stay on the gas by all means, but if not you should break to your leanest breathable gas.

I know that there are experienced divers within GUE who believe that, on short O2 stops (two cycles) taking yourself of O2 for what is quite a large proportion of the prescribed time may compromomise the decompression and that longer exposure is not only OK - but may be desirable.

There is a compromise - come off but do not count the time off the O2 as part of the necessary deco.

The problem with both longer stops and not counting the O2 time is what happens when the deco gets longer - three cyles or more. We should have one rule for everything - if we are happy to do 25 minutes on O2 - then what about a 26 minute stop? or a 28 minute one.....

Looking for hard and fast rules is difficult especially as those at the forefront of our diving are still experimenting and finding out where the boundaries are. We need to protect our lung function - but on little dives like this that *may* be less important than maintaining the O2 within the deco.

At the moment the longest O2 stop I have done has been 25 minutes and I did 20 on and 5 up. Right on the edge of what I would do I guess - and I didn't call deco on that dive (although I was happy to dive it). Had it been me calling stops I think I would have called 12 on, 6 off, 12 on but called a move up after 6 minutes.

graham_hk · September 21st, 2006, 12:04 PM

IMHO if you believe the lungs swell and reduce efficiency of decompression then you have to follow the 12/6 regardless of exposure. I do believe it and therefore never do more than 12 mins on O2 unless it is followed by an ascent or a break. Even if you are not building enough time up on a single dive if you are doing more than one you will quickly.

Breaks should be done on back gas unless that is hypoxic at 6m

Graham

jerry.mobbs · September 21st, 2006, 01:06 PM

Quote: (Originally Posted by Clare Gledhill)

This is something I have been thinking about quite a bit.

GUE teach 12 minutes on maximum. If you are then going to ascend then stay on the gas by all means, but if not you should break to your leanest breathable gas.

I know that there are experienced divers within GUE who believe that, on short O2 stops (two cycles) taking yourself of O2 for what is quite a large proportion of the prescribed time may compromomise the decompression and that longer exposure is not only OK - but may be desirable.

Looking for hard and fast rules is difficult especially as those at the forefront of our diving are still experimenting and finding out where the boundaries are. We need to protect our lung function - but on little dives like this that *may* be less important than maintaining the O2 within the deco.

.

The answer is 'it depends'

If you need to do 30 mins on 02, then 12 on 6, off etc, works great for me.

But, if you need to do 18 mins on O2, then I would not do 12 on 6 off, more like 12 on 3 off 3 on and up.

I agree wth Graham that long 02 exposures impair lung function. So a 3 min break on a short deco is a good way to give your lungs a break. Especially if you are doing multi day diving.

The acid test is to check your lung function after a trip where you have being doing lots of deco. I used to do the full stint on 02 as per the deco programs. To make it worse, on my old CCR i used to run the loop at 1.5 as soon as we left the bottom because I thought I gave me a 'quicker' deco.

But after 2 weeks of doing this, when you get home and run hard. I mean RUN, not jog, the decrease in capacity was very noticable.

Since moving to a 12 on, 6 off (or smaller breaks) deco, any decrease in performance is a -lot- less.

Try it for yourself and see.

Cheers

Jerry

September 20th, 2006, 10:44 PM	#1 (permalink)
indeep(Offline) New Member Join Date: Dec 2005 Location: Deep Posts: 25	Backgas or Deco mix break? Hello all, What are most of you doing as far as 02 breaks from 6m? Let's say you have 20 minutes of deco at 6m.......do most of you take a break?......or will you stay on for the entire 20 minutes? And....do you do your break on backgas?.....or onto your 50%? Thanks in advance.

September 20th, 2006, 10:56 PM	#2 (permalink)
nadwidny(Offline) New Member Join Date: Dec 2005 Location: Edmonton, Alberta Posts: 117	Quote: (Originally Posted by indeep) Hello all, What are most of you doing as far as 02 breaks from 6m? Let's say you have 20 minutes of deco at 6m.......do most of you take a break?......or will you stay on for the entire 20 minutes? And....do you do your break on backgas?.....or onto your 50%? Sometimes take a break. Always on backgas. __________________ Brian My crappy website - members.shaw.ca/nadwidny

September 21st, 2006, 12:41 AM	#3 (permalink)
indeep(Offline) New Member Join Date: Dec 2005 Location: Deep Posts: 25	Little more info. Quote: (Originally Posted by nadwidny) Sometimes take a break. Always on backgas. To your response: 1) Sometimes?......state why or why not. 2) Always backgas?......state why.

September 21st, 2006, 01:58 AM	#4 (permalink)
ppo2_diver(Offline) DIR Practitioner Join Date: Nov 2005 Location: Naperville, IL USA (Chicago Suburb) Posts: 103	For every 12 minutes on O2, I do 6 minutes on back gas. This is assuming that my back gas is breathable at 20 feet. Since I'm not certified for anything deeper than 200 feet, I only use 18/45. So no worries there. I do breaks on back gas to reduce the O2 exposure as much as possible. __________________ Duane A. Johnson Precision Diving

September 21st, 2006, 03:04 AM	#5 (permalink)
nadwidny(Offline) New Member Join Date: Dec 2005 Location: Edmonton, Alberta Posts: 117	Quote: (Originally Posted by indeep) To your response: 1) Sometimes?......state why or why not. 2) Always backgas?......state why. 1. Because sometimes I want to and sometimes I don't 2. To drop the PO2 as low as possible. It's supposed to be a break from high PO2s so there is no sense doing it half-assed. __________________ Brian My crappy website - members.shaw.ca/nadwidny

September 21st, 2006, 04:17 AM	#6 (permalink)
DRE(Offline) New Member Join Date: Nov 2005 Location: Mineola, NY Posts: 162	Quote: (Originally Posted by indeep) Hello all, What are most of you doing as far as 02 breaks from 6m? Let's say you have 20 minutes of deco at 6m.......do most of you take a break?......or will you stay on for the entire 20 minutes? And....do you do your break on backgas?.....or onto your 50%? Thanks in advance. Anything over 20 minutes I'd definitely break; up to 20 minutes will depend on how I feel. __________________ www.dirtydiving.com - DIR is not a 4-letter word!

September 21st, 2006, 09:14 AM	#7 (permalink)
Michael-Fisch(Offline) New Member Join Date: Jul 2006 Location: Germany Posts: 263	If I'm at or over 1.6pp O2 for over 30 minutes, I do breaks on a gas lower than 0.5pp O2 using the 12/6 ratio. Up to 30 minutes I don't bother, since I don't see the advantage with short O2 exposures. Michael

September 21st, 2006, 09:37 AM	#8 (permalink)
Clare Gledhill (Online) GUE Instructor Site Admin Join Date: Nov 2005 Location: UK Posts: 1,540	This is something I have been thinking about quite a bit. GUE teach 12 minutes on maximum. If you are then going to ascend then stay on the gas by all means, but if not you should break to your leanest breathable gas. I know that there are experienced divers within GUE who believe that, on short O2 stops (two cycles) taking yourself of O2 for what is quite a large proportion of the prescribed time may compromomise the decompression and that longer exposure is not only OK - but may be desirable. There is a compromise - come off but do not count the time off the O2 as part of the necessary deco. The problem with both longer stops and not counting the O2 time is what happens when the deco gets longer - three cyles or more. We should have one rule for everything - if we are happy to do 25 minutes on O2 - then what about a 26 minute stop? or a 28 minute one..... Looking for hard and fast rules is difficult especially as those at the forefront of our diving are still experimenting and finding out where the boundaries are. We need to protect our lung function - but on little dives like this that may be less important than maintaining the O2 within the deco. At the moment the longest O2 stop I have done has been 25 minutes and I did 20 on and 5 up. Right on the edge of what I would do I guess - and I didn't call deco on that dive (although I was happy to dive it). Had it been me calling stops I think I would have called 12 on, 6 off, 12 on but called a move up after 6 minutes. __________________ Clare . "Keep away from people who try to belittle your ambitions....Small people always do that, but the really great make you feel that you too can become great." Interested in DIR dive training? Always happy to chat/answer questions so get in touch via PM or visit www.dirdiver.co.uk

September 21st, 2006, 12:04 PM	#9 (permalink)
graham_hk(Offline) Pinoy ako pinoy Join Date: Nov 2005 Location: here, there and everywhere Posts: 779	IMHO if you believe the lungs swell and reduce efficiency of decompression then you have to follow the 12/6 regardless of exposure. I do believe it and therefore never do more than 12 mins on O2 unless it is followed by an ascent or a break. Even if you are not building enough time up on a single dive if you are doing more than one you will quickly. Breaks should be done on back gas unless that is hypoxic at 6m Graham

September 21st, 2006, 01:06 PM	#10 (permalink)
jerry.mobbs(Offline) New Member Join Date: May 2006 Location: asia Posts: 288	Quote: (Originally Posted by Clare Gledhill) This is something I have been thinking about quite a bit. GUE teach 12 minutes on maximum. If you are then going to ascend then stay on the gas by all means, but if not you should break to your leanest breathable gas. I know that there are experienced divers within GUE who believe that, on short O2 stops (two cycles) taking yourself of O2 for what is quite a large proportion of the prescribed time may compromomise the decompression and that longer exposure is not only OK - but may be desirable. Looking for hard and fast rules is difficult especially as those at the forefront of our diving are still experimenting and finding out where the boundaries are. We need to protect our lung function - but on little dives like this that may be less important than maintaining the O2 within the deco. . The answer is 'it depends' If you need to do 30 mins on 02, then 12 on 6, off etc, works great for me. But, if you need to do 18 mins on O2, then I would not do 12 on 6 off, more like 12 on 3 off 3 on and up. I agree wth Graham that long 02 exposures impair lung function. So a 3 min break on a short deco is a good way to give your lungs a break. Especially if you are doing multi day diving. The acid test is to check your lung function after a trip where you have being doing lots of deco. I used to do the full stint on 02 as per the deco programs. To make it worse, on my old CCR i used to run the loop at 1.5 as soon as we left the bottom because I thought I gave me a 'quicker' deco. But after 2 weeks of doing this, when you get home and run hard. I mean RUN, not jog, the decrease in capacity was very noticable. Since moving to a 12 on, 6 off (or smaller breaks) deco, any decrease in performance is a -lot- less. Try it for yourself and see. Cheers Jerry __________________ -------------------- www.crossfit.com The DIR of Fitness