mCCR and zero viz exit

lizardland · 31st March 2008, 15:41

Quote: (Originally Posted by sfldiver)

I agree; however, if you're in zero viz enviroment and you really can't read your handsets or your HUD, then when you do switch to oc, how will you be able to make the appropriate switch on your computer(s) to oc mode to have it/them properly calculate the decompression requirements?

If you can't see your gauges then why does it matter?

Go to your bail out tables (you do have a bail out table, don't you?

) and modify based on what you think happened.

caverkevin · 31st March 2008, 15:49

I am going to disagree. I think the only way you are not going to see the HUD is if your eyes are closed or you have mud packed in between the HUD and the mask. If you still are running your light in a silt out, I could see that amount of light might make it hard to read. Reducing the amount of light should make the HUD more readable.

Just like when I got trapped inside a collapsing big shipwreck in 65 meters of dark water. I cupped my light and spotted just enough day light to find my way out. My line was buried under a meter of wood and boards. I could not see in the silt out with the light.

Bottom line, only breathe what you can trust.

Cheers!!

Kevin

Quote: (Originally Posted by mattmexico)

yo

The diver had a Shearwater HUD on the unit but was in zero viz, as zero viz drill. From experience I can say there are circumstances I doubt you could see any HUD in real zero viz silt out.

The only HUD that could deal with that ( as far as I know but please correct me if wrong ) would be the DIVA from the Optima - Hammerhead electronics as it does vibrate when goint off range hyper or hypo.

Matt

Mark Chase · 31st March 2008, 16:04

Quote: (Originally Posted by mattmexico)

yo Marc

Yes it was you that made me thinking. While not naming names I did not want to turn the discussion into individual finger pointing but rather have it going toward CCR cave diving procedures and what I or we can learn from it.

I truely enjoyed the course with the three of you and am happy to keep on learning myself ... and enjoyed the write up you posted on the Yorkshire Divers forum. You mind posting it here ?.

greetings
Matt

I did put it on hear as well

http://www.rebreatherworld.com/trip-...co-protec.html

It was one of those incidents that wake you up as a MCCR diver. First priority is to ensure you have a breathable gas, everything else comes second.

One of the many valuable lessons I learned on the course.

ATB

Mark

Dutchy · 31st March 2008, 16:18

Quote: (Originally Posted by PhilSiswick)

An interesting thought and one we may forget easily. When I learned to fly, my instructor told me that three most useless things to me were: fuel in the bowser on the ground, height above me and runway behind me :-) Available and accessible gas in cylinders when you've stopped breathing is probably even less use than those!

Cheers,

Fuel? -Shrug- I'm a glider pilot

Other than that I concur.
On topic: My instructor told me that OC is always an option (BOV) but you should go SC to buy yourself extra time when possible (which may well be after goiing OC to start with). All the loop tricks are great if you really have to use them and remain at the same depth. I read an article from Richard Pyle describing even more advanced loop mixing but am inclined to say that you screwed up bigtime (or are an alpinist) if you have to resort to that.

**Gill Envy** · 31st March 2008, 16:36

After watching a solenoid stop working mid dive and then start working spontaniously (and that was after a trip back to the hatchery) I've come to the conclusion that eCCR's need an even shorter monitoring interval than mCCR's as you have no MFO and even less time to react to a failing set point controller and no obvious way of calculating the timing of a failure. Having looked hard at the stats, and compared my behavior on eCCR vs mCCR I don't even think one's greatest risk on an eCCR is controller failure though, but rather the propensity to become too lax and trusting that a "force beyond yourself" is going to catch you when you fall... to barrow a term, "function creep", is the siren call of eCCR's (the propensity to over rely on a device because of the ease of it's availability).

If I were diving any CCR with my eyes closed, I'd be off the loop if I could not see my HUD or wrist unit, lickety split if the situation did not resolve by the time I ran out of gas then i'd go back on the loop and continue SCR. I have to say, diving in cold murky water, i've been in plenty of situations where I could not see two inches in front of me but i've never not been able to see my HUD and since it gives me real time po2 on all three cells, i'm able to continue flying it with a relative degree of confidence.

that said, if my head was being held down in the mud, hands tied behind back, unable to push HUD against face plate or inject o2, or bail out ... I'd simply revert to the old "in case of nuke" drill: put head between legs, kiss ass good bye! ... on any rebreather.

**sfldiver** · 31st March 2008, 16:42

Quote: (Originally Posted by lizardland)

If you can't see your gauges then why does it matter?

Go to your bail out tables (you do have a bail out table, don't you?

) and modify based on what you think happened.

I never imagined this scecario occurring to me, because even though I have done some cave training on oc, I exclusively dive in high visibility beautiful South Florida waters and always at lease two computers that are capable of being switched to oc mode at anytime. I always run a bailout plan online to ensure that I have enough gas for a reasonable worst case scenario, but I do not carry it with me, because I never assumed I would not have enough visibility to switch my handsets to oc mode or see my PO2. However, in the future, and especially after reading this thread, I will carry bailout tables if I intend on diving anywhere involving serious penetration and the potential for zero viz conditions, just incase this situation rears it's ugly face. But then again, I dive an eccr, so a little extra sh_t would have to hit the fan for this scenario to occur and really screw me!

Good discussion - Thanks for the heads up!

Meng_Tze · 31st March 2008, 18:34

Supposing you can not read a HUD in zero vis, having a bailout table is also useless? Anything requiring visual reference is useless.......

There would be a physical obstruction between your eyes and the outside world for one not to see anything (true zero vis). Not even the glow of the HUD/lights and such would be seen. This I do not think is a realistic scenario.

**sfldiver** · 31st March 2008, 19:03

Quote: (Originally Posted by Meng_Tze)

Supposing you can not read a HUD in zero vis, having a bailout table is also useless? Anything requiring visual reference is useless.......

There would be a physical obstruction between your eyes and the outside world for one not to see anything (true zero vis). Not even the glow of the HUD/lights and such would be seen. This I do not think is a realistic scenario.

It is rather difficult to imagine a scenario where conditions were so bad that your HUD would not be visible to you.

I like split pea soup, but I don't like diving in it - That's why I live and dive in South Florida!

**Gill Envy** · 31st March 2008, 19:08

Quote: (Originally Posted by Meng_Tze)

Supposing you can not read a HUD in zero vis, having a bailout table is also useless? Anything requiring visual reference is useless.......

There would be a physical obstruction between your eyes and the outside world for one not to see anything (true zero vis). Not even the glow of the HUD/lights and such would be seen. This I do not think is a realistic scenario.

Ok, tell you what i'm going to do, I'll take an extra face mask with me on my next dive and un-clip the shearwater HUD and hold it up to the mask as I press it into the mud. I'll take a picture from the other side of the glass and post it. If I can't get a photo with the HUD clearly visible, I'll concede that there is such a potential for true zero vis "as if eyes closed" scenario. And I'll keep doing what i've been doing... adjust my practices accordingly to to reflect the level of risk i'm comfortable with. Actually, maybe making up some split pea soup would be easier...;-).

Relying entirely on a setp point controller or entirely on a HUD and manual injection are both high risk scenarios, IMHO.

g

PCDiver · 31st March 2008, 19:10

Quote: (Originally Posted by Meng_Tze)

There would be a physical obstruction between your eyes and the outside world for one not to see anything (true zero vis). Not even the glow of the HUD/lights and such would be seen. This I do not think is a realistic scenario.

Never been in a wreck with a total silt out? The dust in some of the wrecks has a very fine structure. It is very easy to reduce vis to almost nothing with only couple of wrong fin kicks. Been there, done that.

31st March 2008, 15:41	#31 (permalink)
lizardland Yak Current Rebreather/s: Classic Kiss Ray Home Build Other Rebreather/s: Ray Home Build Join Date: Mar 2005 Location: North... Posts: 1,137	Re: mCCR and zero viz exit Quote: (Originally Posted by sfldiver) I agree; however, if you're in zero viz enviroment and you really can't read your handsets or your HUD, then when you do switch to oc, how will you be able to make the appropriate switch on your computer(s) to oc mode to have it/them properly calculate the decompression requirements? If you can't see your gauges then why does it matter? Go to your bail out tables (you do have a bail out table, don't you?) and modify based on what you think happened. __________________ 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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31st March 2008, 15:49	#32 (permalink)
caverkevin CK #159 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Apr 2005 Location: Broadway NC Posts: 90	Re: mCCR and zero viz exit I am going to disagree. I think the only way you are not going to see the HUD is if your eyes are closed or you have mud packed in between the HUD and the mask. If you still are running your light in a silt out, I could see that amount of light might make it hard to read. Reducing the amount of light should make the HUD more readable. Just like when I got trapped inside a collapsing big shipwreck in 65 meters of dark water. I cupped my light and spotted just enough day light to find my way out. My line was buried under a meter of wood and boards. I could not see in the silt out with the light. Bottom line, only breathe what you can trust. Cheers!! Kevin Quote: (Originally Posted by mattmexico) yo The diver had a Shearwater HUD on the unit but was in zero viz, as zero viz drill. From experience I can say there are circumstances I doubt you could see any HUD in real zero viz silt out. The only HUD that could deal with that ( as far as I know but please correct me if wrong ) would be the DIVA from the Optima - Hammerhead electronics as it does vibrate when goint off range hyper or hypo. Matt
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31st March 2008, 16:04	#33 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Jan 2005 Location: Kent Posts: 2,406	Re: mCCR and zero viz exit Quote: (Originally Posted by mattmexico) yo Marc Yes it was you that made me thinking. While not naming names I did not want to turn the discussion into individual finger pointing but rather have it going toward CCR cave diving procedures and what I or we can learn from it. I truely enjoyed the course with the three of you and am happy to keep on learning myself ... and enjoyed the write up you posted on the Yorkshire Divers forum. You mind posting it here ?. greetings Matt I did put it on hear as well http://www.rebreatherworld.com/trip-...co-protec.html It was one of those incidents that wake you up as a MCCR diver. First priority is to ensure you have a breathable gas, everything else comes second. One of the many valuable lessons I learned on the course. 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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31st March 2008, 16:18	#34 (permalink)
Dutchy SK#007 Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: Apr 2006 Location: Nieuwegein (The Netherlands) Posts: 693	Re: mCCR and zero viz exit Quote: (Originally Posted by PhilSiswick) An interesting thought and one we may forget easily. When I learned to fly, my instructor told me that three most useless things to me were: fuel in the bowser on the ground, height above me and runway behind me :-) Available and accessible gas in cylinders when you've stopped breathing is probably even less use than those! Cheers, Fuel? -Shrug- I'm a glider pilot Other than that I concur. On topic: My instructor told me that OC is always an option (BOV) but you should go SC to buy yourself extra time when possible (which may well be after goiing OC to start with). All the loop tricks are great if you really have to use them and remain at the same depth. I read an article from Richard Pyle describing even more advanced loop mixing but am inclined to say that you screwed up bigtime (or are an alpinist) if you have to resort to that. __________________ = This post is environmentally friendly. It is composed of 100% recycled electrons only. = SK #007
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31st March 2008, 16:36	#35 (permalink)
Gill Envy Shearwater Copis Diver Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,207	Re: mCCR and zero viz exit After watching a solenoid stop working mid dive and then start working spontaniously (and that was after a trip back to the hatchery) I've come to the conclusion that eCCR's need an even shorter monitoring interval than mCCR's as you have no MFO and even less time to react to a failing set point controller and no obvious way of calculating the timing of a failure. Having looked hard at the stats, and compared my behavior on eCCR vs mCCR I don't even think one's greatest risk on an eCCR is controller failure though, but rather the propensity to become too lax and trusting that a "force beyond yourself" is going to catch you when you fall... to barrow a term, "function creep", is the siren call of eCCR's (the propensity to over rely on a device because of the ease of it's availability). If I were diving any CCR with my eyes closed, I'd be off the loop if I could not see my HUD or wrist unit, lickety split if the situation did not resolve by the time I ran out of gas then i'd go back on the loop and continue SCR. I have to say, diving in cold murky water, i've been in plenty of situations where I could not see two inches in front of me but i've never not been able to see my HUD and since it gives me real time po2 on all three cells, i'm able to continue flying it with a relative degree of confidence. that said, if my head was being held down in the mud, hands tied behind back, unable to push HUD against face plate or inject o2, or bail out ... I'd simply revert to the old "in case of nuke" drill: put head between legs, kiss ass good bye! ... on any rebreather. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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31st March 2008, 16:42	#36 (permalink)
sfldiver Team Optima Diver Current Rebreather/s: Optima Other Rebreather/s: Join Date: Jul 2007 Location: Pompano Beach, FL Posts: 627	Re: mCCR and zero viz exit Quote: (Originally Posted by lizardland) If you can't see your gauges then why does it matter? Go to your bail out tables (you do have a bail out table, don't you?) and modify based on what you think happened. I never imagined this scecario occurring to me, because even though I have done some cave training on oc, I exclusively dive in high visibility beautiful South Florida waters and always at lease two computers that are capable of being switched to oc mode at anytime. I always run a bailout plan online to ensure that I have enough gas for a reasonable worst case scenario, but I do not carry it with me, because I never assumed I would not have enough visibility to switch my handsets to oc mode or see my PO2. However, in the future, and especially after reading this thread, I will carry bailout tables if I intend on diving anywhere involving serious penetration and the potential for zero viz conditions, just incase this situation rears it's ugly face. But then again, I dive an eccr, so a little extra sh_t would have to hit the fan for this scenario to occur and really screw me! Good discussion - Thanks for the heads up! __________________ *Currently piloting & shooting...* Dive Rite O2ptima FX Rigged w/ a Dsix Custom Aluminum Frame, Nomad Wing, Transpac Harness and VR3 Computer w/ VPM-B/E & a 4th Cell Sensor Link.* Canon PowerShot G9 Digital Camera Rigged in a Patima-PDCH 2008 G9 Aluminum Housing w/ an Inon UWL-100 Achromat Wide Conversion Lens, 2 Inon UCL-165M67 Close-Up Lenses and 2 Inon Z-240 Strobes. Last edited by sfldiver : 31st March 2008 at 16:45.*
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31st March 2008, 18:34	#37 (permalink)
Meng_Tze 246 Bubbleless Cove Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jan 2007 Location: FL, USA Posts: 101	Re: mCCR and zero viz exit Supposing you can not read a HUD in zero vis, having a bailout table is also useless? Anything requiring visual reference is useless....... There would be a physical obstruction between your eyes and the outside world for one not to see anything (true zero vis). Not even the glow of the HUD/lights and such would be seen. This I do not think is a realistic scenario. __________________ Homo Bonae Voluntatis
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31st March 2008, 19:03	#38 (permalink)
sfldiver Team Optima Diver Current Rebreather/s: Optima Other Rebreather/s: Join Date: Jul 2007 Location: Pompano Beach, FL Posts: 627	Re: mCCR and zero viz exit Quote: (Originally Posted by Meng_Tze) Supposing you can not read a HUD in zero vis, having a bailout table is also useless? Anything requiring visual reference is useless....... There would be a physical obstruction between your eyes and the outside world for one not to see anything (true zero vis). Not even the glow of the HUD/lights and such would be seen. This I do not think is a realistic scenario. It is rather difficult to imagine a scenario where conditions were so bad that your HUD would not be visible to you. I like split pea soup, but I don't like diving in it - That's why I live and dive in South Florida! __________________ *Currently piloting & shooting...* Dive Rite O2ptima FX Rigged w/ a Dsix Custom Aluminum Frame, Nomad Wing, Transpac Harness and VR3 Computer w/ VPM-B/E & a 4th Cell Sensor Link.* Canon PowerShot G9 Digital Camera *Rigged in a Patima-PDCH 2008 G9 Aluminum Housing w/ an Inon UWL-100 Achromat Wide Conversion Lens, 2 Inon UCL-165M67 Close-Up Lenses and 2 Inon Z-240 Strobes.
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31st March 2008, 19:08	#39 (permalink)
Gill Envy Shearwater Copis Diver Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,207	Re: mCCR and zero viz exit Quote: (Originally Posted by Meng_Tze) Supposing you can not read a HUD in zero vis, having a bailout table is also useless? Anything requiring visual reference is useless....... There would be a physical obstruction between your eyes and the outside world for one not to see anything (true zero vis). Not even the glow of the HUD/lights and such would be seen. This I do not think is a realistic scenario. Ok, tell you what i'm going to do, I'll take an extra face mask with me on my next dive and un-clip the shearwater HUD and hold it up to the mask as I press it into the mud. I'll take a picture from the other side of the glass and post it. If I can't get a photo with the HUD clearly visible, I'll concede that there is such a potential for true zero vis "as if eyes closed" scenario. And I'll keep doing what i've been doing... adjust my practices accordingly to to reflect the level of risk i'm comfortable with. Actually, maybe making up some split pea soup would be easier...;-). Relying entirely on a setp point controller or entirely on a HUD and manual injection are both high risk scenarios, IMHO. g __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°> Last edited by Gill Envy : 31st March 2008 at 19:10.
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31st March 2008, 19:10	#40 (permalink)
PCDiver Submerge Productions Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Belgium Posts: 877	Re: mCCR and zero viz exit Quote: (Originally Posted by Meng_Tze) There would be a physical obstruction between your eyes and the outside world for one not to see anything (true zero vis). Not even the glow of the HUD/lights and such would be seen. This I do not think is a realistic scenario. Never been in a wreck with a total silt out? The dust in some of the wrecks has a very fine structure. It is very easy to reduce vis to almost nothing with only couple of wrong fin kicks. Been there, done that. __________________ >>>>> www.submergeproductions.com dedicated to promoting technical diving >>>>> Check out our dive show video interviews at http://www.submergeproductions.com/A...nterviews.aspx >>>>> Wreck dive videos http://www.submergeproductions.com/A...omthedeep.aspx
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