Think piece: rebreather breathing on the surface

Drmike · 17th October 2007, 04:29

Quote: (Originally Posted by bluedjango1)

doubtful... if you are going to deal at only one atmosphere how will any of what you mentioned earlier be relevant in any way?

the military has been using it for years... at least our's has...

on the surface we (divers) are dealing with 1 atmosphere yes?

on the surface we are breathing from an Rebreather yes?

on the surface we have to do all those things I listed yes?

his patients are breathing 1 atmosphere yes, but there the similarity ends. ergo his comment that theres no issue with breathing machine at 1 atmosophere is only relevant to his patients (who arent doing any of the above listed activities, nor montoring and maintaining their own loop ppo2)

bluedjango1 · 17th October 2007, 04:37

Quote: (Originally Posted by Drmike)

on the surface we (divers) are dealing with 1 atmosphere yes?

on the surface we are breathing from an Rebreather yes?

on the surface we have to do all those things I listed yes?

his patients are breathing 1 atmosphere yes, but there the similarity ends. ergo his comment that theres no issue with breathing machine at 1 atmosophere is only relevant to his patients (who arent doing any of the above listed activities, nor montoring and maintaining their own loop ppo2)

I agree completely... and I ran this off course a bit, as was not my intention!

Never saw your first post which I agree with as well...

Quote: (Originally Posted by Drmike)

I hope you know the answer to this question already.
If you dont know the answer to this you might want to consider if you are knowledgeable enough to be diving a rebreather - this is IMO fundamental stuff - have you done a course? was this not covered? perhaps you just forgot. If you really dont know then perhaps you should do your self and your family a favour and sell it or get some formal/better training before we read about another shallow water/surface rebeather death - hey you could be this months lucky winner! Hmm......Wonder who it will be that dies this month? The suspense is killing me (if you excuse the pun)

sorry for the rant - haven't had my morning cup yet - and am still bothered by the 1 death/month on rebreather thing. When I read a question such as this that is 'basic' being asked by a Rebreather diver I just think something is really wrong somewhere. Is it the training? students retention of facts? what is it?

Maybe you had a legitimate reason to ask this question and are aware of the answer in which case my apologies.

There was a good thread about this before here you may want to look up in the archives

my only point was... if 'YOU' are not monitoring the loop, regardless of depth,
rebreathers are dangerous

Abbo · 17th October 2007, 05:53

For me, I get off the loop as soon as I surface, if at all possible. There are more distractions at the surface, yet the physical work rate is higher, finning to the boat. That seems a witch's brew that substantially increases the risk of breathing a hypoxic mixture and dying with no advance warning. If you have to do it, make sure the set point is high enough to give yourself a margin for error.

Drmike · 17th October 2007, 06:10

Quote: (Originally Posted by Abbo)

For me, I get off the loop as soon as I surface, if at all possible. There are more distractions at the surface, yet the physical work rate is higher, finning to the boat. That seems a witch's brew that substantially increases the risk of breathing a hypoxic mixture and dying with no advance warning. If you have to do it, make sure the set point is high enough to give yourself a margin for error.

Personally I revert to manually injecting O2 as soon as I hit the surface at surface (PPO2 cant go over 1 so who cares wasting a bit of O2) - often cant look at the displays if struggling in bad sea conditions, I hit surface with ppo2 of 1 anyway after deco so manual inject ensures good high ppo2 is maintained (ie I ignore solenoid firing and assume unit is not maintaining setpoint)

- discussed in thread

http://www.rebreatherworld.com/rebreather-accidents-incidents/10607-hypoxia-near-drowning-stoney-cove-3rd-6.html

UKSteve · 17th October 2007, 06:13

Quote: (Originally Posted by Gilles)

IMV, being at near surface (or very beginning) is just as dangerous as say,.. a 50m+ deco dive. Worse if you're unnecessarily using hypoxic diluents.

I don't see the significance of whether the hypoxic diluent is "necessary" or not. Pure 10/xx will knock you out either way if you breath it at surface (I believe). Not sure about 16/xx but you will struggle if you start to work hard.

It's another reason I switch off my ADV when ascending.

An interesting point was made about getting off the loop ASAP after surfacing. I have always stayed on the loop - monitoring regularly and manually adding O2 regularly too - to get max benefit from the CCR i.e. breathing pure O2 for a while. After a long hang (30 mins ++) I also tend to stay on the loop for 5 mins or so on the boat too. In addition to the HUD and hand set, with the ADV closed I am prompted to add more O2 by a change in bouyancy or starting to bottom out the lungs. I also tend to flush the loop to pure (ish) O2 at 6m and again at surface.

Dr Mike made a great point in a different thread .. if you stay in your set you have option of rapidly reentering the water if you get the urge to do some in water recompression.

Steve

Abbo · 17th October 2007, 06:27

Quote: (Originally Posted by Drmike)

Personally I revert to manually injecting O2 as soon as I hit the surface at surface (PPO2 cant go over 1 so who cares wasting a bit of O2) - often cant look at the displays if struggling in bad sea conditions, I hit surface with ppo2 of 1 anyway after deco so manual inject ensures good high ppo2 is maintained (ie I ignore solenoid firing and assume unit is not maintaining setpoint)

Your strategy makes more sense. Thanks

PCDiver · 17th October 2007, 09:24

Quote: (Originally Posted by Abbo)

Your strategy makes more sense. Thanks

DrMike's "strategy" should be the ONLY one used by ALL rebreather divers!

lizardland · 17th October 2007, 12:10

Quote: (Originally Posted by PCDiver)

DrMike's "strategy" should be the ONLY one used by ALL rebreather divers!

Exactly what I do, at 6m or less I'm on O2 and the ADV is off and I always get in the water on a pure O2 loop. My worst rebreather experience to date was feeling the lights going out whilst I was putting my fins on standing in 1m of water.

Drmike · 17th October 2007, 12:14

Quote: (Originally Posted by bluedjango1)

I agree completely... and I ran this off course a bit, as was not my intention!

Never saw your first post which I agree with as well...

my only point was... if 'YOU' are not monitoring the loop, regardless of depth,
rebreathers are dangerous

of course, and my point was if you are not monitoring your loop they are more dangerous at the surface than at depth

Joe · 17th October 2007, 15:26

Quote: (Originally Posted by Drmike)

of course, and my point was if you are not monitoring your loop they are more dangerous at the surface than at depth

I agree with you 100%

Far more dangerous on the surface. My ADV is *always* closed once I reach depth and except when scootering to depth at a rapid pace (ie - hit 300 fsw in 60 - 90 secs.) it is opened and closed intermittently on decent.

On ascent the ADV is closed. No need for it as the gas is expanding and the PO2 is dropping. After 20ft you can safely use O2 only. On the surface if heavy seas prevent me from looking at the monitor I simply lean on the O2 button. It can't hurt you and I *never* trust the solenoid to maintain a PPO2. I use it as a fail safe. Also, you should have a good idea of how long it takes for you to breathe the loop down *and* if you are using minimum loop volume you will metabolize enought gas that you will feel the need to add gas way before you become hypoxic.

17th October 2007, 04:29	#11 (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: 3,128	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by bluedjango1) doubtful... if you are going to deal at only one atmosphere how will any of what you mentioned earlier be relevant in any way? the military has been using it for years... at least our's has... on the surface we (divers) are dealing with 1 atmosphere yes? on the surface we are breathing from an Rebreather yes? on the surface we have to do all those things I listed yes? his patients are breathing 1 atmosphere yes, but there the similarity ends. ergo his comment that theres no issue with breathing machine at 1 atmosophere is only relevant to his patients (who arent doing any of the above listed activities, nor montoring and maintaining their own loop ppo2) __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
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17th October 2007, 04:37	#12 (permalink)
bluedjango1 New Member Current Rebreather/s: Other CCR Other Rebreather/s: Megalodon Other CCR Join Date: Jan 2007 Location: High Springs Posts: 34	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by Drmike) on the surface we (divers) are dealing with 1 atmosphere yes? on the surface we are breathing from an Rebreather yes? on the surface we have to do all those things I listed yes? his patients are breathing 1 atmosphere yes, but there the similarity ends. ergo his comment that theres no issue with breathing machine at 1 atmosophere is only relevant to his patients (who arent doing any of the above listed activities, nor montoring and maintaining their own loop ppo2) I agree completely... and I ran this off course a bit, as was not my intention! Never saw your first post which I agree with as well... Quote: (Originally Posted by Drmike) I hope you know the answer to this question already. If you dont know the answer to this you might want to consider if you are knowledgeable enough to be diving a rebreather - this is IMO fundamental stuff - have you done a course? was this not covered? perhaps you just forgot. If you really dont know then perhaps you should do your self and your family a favour and sell it or get some formal/better training before we read about another shallow water/surface rebeather death - hey you could be this months lucky winner! Hmm......Wonder who it will be that dies this month? The suspense is killing me (if you excuse the pun) sorry for the rant - haven't had my morning cup yet - and am still bothered by the 1 death/month on rebreather thing. When I read a question such as this that is 'basic' being asked by a Rebreather diver I just think something is really wrong somewhere. Is it the training? students retention of facts? what is it? Maybe you had a legitimate reason to ask this question and are aware of the answer in which case my apologies. There was a good thread about this before here you may want to look up in the archives my only point was... if 'YOU' are not monitoring the loop, regardless of depth, rebreathers are dangerous __________________ Safe diving, Corey
(Online)

17th October 2007, 05:53	#13 (permalink)
Abbo Going down on Meg Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 418	Re: Think piece: rebreather breathing on the surface For me, I get off the loop as soon as I surface, if at all possible. There are more distractions at the surface, yet the physical work rate is higher, finning to the boat. That seems a witch's brew that substantially increases the risk of breathing a hypoxic mixture and dying with no advance warning. If you have to do it, make sure the set point is high enough to give yourself a margin for error.
(Offline)

17th October 2007, 06:10	#14 (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: 3,128	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by Abbo) For me, I get off the loop as soon as I surface, if at all possible. There are more distractions at the surface, yet the physical work rate is higher, finning to the boat. That seems a witch's brew that substantially increases the risk of breathing a hypoxic mixture and dying with no advance warning. If you have to do it, make sure the set point is high enough to give yourself a margin for error. Personally I revert to manually injecting O2 as soon as I hit the surface at surface (PPO2 cant go over 1 so who cares wasting a bit of O2) - often cant look at the displays if struggling in bad sea conditions, I hit surface with ppo2 of 1 anyway after deco so manual inject ensures good high ppo2 is maintained (ie I ignore solenoid firing and assume unit is not maintaining setpoint) - discussed in thread http://www.rebreatherworld.com/rebreather-accidents-incidents/10607-hypoxia-near-drowning-stoney-cove-3rd-6.html __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
(Offline)

17th October 2007, 06:13	#15 (permalink)
UKSteve Still a novice... Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Jul 2005 Location: Weymouth, UK Posts: 572	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by Gilles) IMV, being at near surface (or very beginning) is just as dangerous as say,.. a 50m+ deco dive. Worse if you're unnecessarily using hypoxic diluents. I don't see the significance of whether the hypoxic diluent is "necessary" or not. Pure 10/xx will knock you out either way if you breath it at surface (I believe). Not sure about 16/xx but you will struggle if you start to work hard. It's another reason I switch off my ADV when ascending. An interesting point was made about getting off the loop ASAP after surfacing. I have always stayed on the loop - monitoring regularly and manually adding O2 regularly too - to get max benefit from the CCR i.e. breathing pure O2 for a while. After a long hang (30 mins ++) I also tend to stay on the loop for 5 mins or so on the boat too. In addition to the HUD and hand set, with the ADV closed I am prompted to add more O2 by a change in bouyancy or starting to bottom out the lungs. I also tend to flush the loop to pure (ish) O2 at 6m and again at surface. Dr Mike made a great point in a different thread .. if you stay in your set you have option of rapidly reentering the water if you get the urge to do some in water recompression. Steve
(Online)

17th October 2007, 06:27	#16 (permalink)
Abbo Going down on Meg Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 418	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by Drmike) Personally I revert to manually injecting O2 as soon as I hit the surface at surface (PPO2 cant go over 1 so who cares wasting a bit of O2) - often cant look at the displays if struggling in bad sea conditions, I hit surface with ppo2 of 1 anyway after deco so manual inject ensures good high ppo2 is maintained (ie I ignore solenoid firing and assume unit is not maintaining setpoint) Your strategy makes more sense. Thanks
(Offline)

17th October 2007, 09:24	#17 (permalink)
PCDiver Submerge Productions Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Belgium Posts: 933	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by Abbo) Your strategy makes more sense. Thanks DrMike's "strategy" should be the ONLY one used by ALL rebreather divers!
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17th October 2007, 12:10	#18 (permalink)
lizardland Yak Current Rebreather/s: MK 15.X Home Build Other Rebreather/s: Classic Kiss Home Build Join Date: Mar 2005 Location: North... Posts: 1,236	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by PCDiver) DrMike's "strategy" should be the ONLY one used by ALL rebreather divers! Exactly what I do, at 6m or less I'm on O2 and the ADV is off and I always get in the water on a pure O2 loop. My worst rebreather experience to date was feeling the lights going out whilst I was putting my fins on standing in 1m of water. __________________ Can you imagine drifting along in the sea with your mouth open and a load of f***ing plankton going in? You'd like it, would you? www.westons-cider.co.uk Azerbaijani Association of Technical Divers Publicity Officer and Goat Wrangler
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17th October 2007, 12:14	#19 (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: 3,128	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by bluedjango1) I agree completely... and I ran this off course a bit, as was not my intention! Never saw your first post which I agree with as well... my only point was... if 'YOU' are not monitoring the loop, regardless of depth, rebreathers are dangerous of course, and my point was if you are not monitoring your loop they are more dangerous at the surface than at depth __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
(Offline)

17th October 2007, 15:26	#20 (permalink)
Joe Custom Title Allowed! Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Oct 2005 Location: Florida, USA Posts: 247	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by Drmike) of course, and my point was if you are not monitoring your loop they are more dangerous at the surface than at depth I agree with you 100% Far more dangerous on the surface. My ADV is always closed once I reach depth and except when scootering to depth at a rapid pace (ie - hit 300 fsw in 60 - 90 secs.) it is opened and closed intermittently on decent. On ascent the ADV is closed. No need for it as the gas is expanding and the PO2 is dropping. After 20ft you can safely use O2 only. On the surface if heavy seas prevent me from looking at the monitor I simply lean on the O2 button. It can't hurt you and I never trust the solenoid to maintain a PPO2. I use it as a fail safe. Also, you should have a good idea of how long it takes for you to breathe the loop down and if you are using minimum loop volume you will metabolize enought gas that you will feel the need to add gas way before you become hypoxic.
(Offline)

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