deco plan when running semiclosed

Drmike · 15th June 2007, 03:03

Quote: (Originally Posted by tecdivertraining)

.

A more in-depth discussion should at least take place during the academic session of mod 1 training even if the diver is far away from making this dive having just passed their course. soon they may be thinking about hitting these depth without considering the bailout gas requirements.

.

Hey Matt,
I fully agree. SCR bail is part of Mod1, my understanding from whats being reported here is its being taught in mod 1 without mention of the drop in ppo2 and subesequently how to use that info (re:future deco) to calc deco

I think if this is the case its kinda dumb.

We preach the ALWAYS KNOW YOUR PPO2

Yet we are teaching students to bail to semniclosed in mod1 and not to think about what they are breathing? not to be aware of how running semclosed effects their ppo2?

I appreciate that a mod1 diver is fully saturated with new things to learn on their course but how does this sound:?

During scr running on a mod1 course:

Instructor: "Ok now look at your display, see how your loop ppo2 is stabalising at a ppo2 just below the ppo2 of the dil at this depth - in future you will use that drop to calculate deco should you have to do scr bail on a deco dive."

Student: "Yeh but Im only MOD1 and noooo mod1 diver ever goes straight out and does deco dives after their course and will aways wait to do deco dives before they do mod2 or 3

so please dont tell me stuff I dont need to know

...meanwhile back at the ranch

ps, organising a trip over soon

divelermentov · 15th June 2007, 06:17

Quote: (Originally Posted by tecdivertraining)

Mike I tend to agree with you that SCR mode should be covered more in-depth.

My thinking on this is Mod 1 divers are usually certified to dive to around 40m.

So here is the scenario:

A diver plans a dive to 40m for 25min resulting in 10 min limited deco obligation (planed using v-planner using my personal config) if at the last minute of the dive they had to bailout that would result in an increase of runtime from 40min to 73 min. quite a big jump considering the amount of bailout gas some dives choose to carry and the stress that could be encountered. My personal requirements would call for around a 1000 liters of gas to complete that deco, that’s assuming its not a CO2 issue.

So introducing SCR in this case could avoid a diver surfacing and missing all that required deco due to inefficient gas planning. Some of the divers I have had the pleasure of diving with have never even considered this eventuality and would have been faced with lengthy deco obligations with no reel understanding of decompression diving techniques.

A more in-depth discussion should at least take place during the academic session of mod 1 training even if the diver is far away from making this dive having just passed their course. soon they may be thinking about hitting these depth without considering the bailout gas requirements.

Just my two cents worth.

this was exactly the scenario I was thinking of,

even going only into marginal deco, lets say 10 minutes, it is still a deco obligation. Therefore my question how to calculate teh drop in po2.

Sorry for causing such an emotionla discusson with regards to who does what training to what standard, wasn't my intend to obset people.

My question was merly of practical nature how to determine which computer setting to use to allow for the ppo2 drop.

Mike - do i read your posts correctly to observe the ppo2 drop at a given venting ratio and than use the drop ppo2 % to adjust your Vr3 ?

***EBT*** · 15th June 2007, 08:46

Its already been posted, but for the sake of clarity;

The FiO2 depends on drive gas, loop volume, dump ratio and Tidal volume. So in practise this means the drop in %O2 from the dil is diver and unit specific. Whats normally suggested is that people do a real dive, with real diluents and do SCR mode. You then watch your displays and build your own table of %O2 drop and use this with a deco package of your choice (or a complicator like a VR£).

Its not a MOD1 skill and Mike, sorry but you started that whole debate (incidentally, your standards are out of date).

This is also why people get nervous of hypoxic dils when you dont need them... they compromise your SCR capabilities from a deco perspective.

/Zak

Mark Chase · 15th June 2007, 08:53

Quote: (Originally Posted by OceanOpportunity)

while I hate these online pissing matches, I think that DrMike's reference to Mod1 came from an assumption that the original poster should have received this scr bailout training in Mod1. Doing a little reading between the lines, it seems that the poster may not have completed any mod2 or mod3 level training, just 'mod1' with Leon, and posted a simple inquiry on how to address scr bailout deco calculations.

for all intents and purposes, diving beyond a mod1 level of training without being trained probably isnt the best of ideas. For sake of answering the original question...if incurring a deco obligation of more time than can be adequately accounted for with a controlled scr ascent followed by OC decompression with what you are carrying, then its time to rethink the requirements for the dive..be it more OC, more training in scr bailout, or a computer configuration that sniffs the gas while in scr

Mod 1 CCR air dill no deco (Unless decompresion procedures qualified on OC)

Which most of us are, so yes you can rack up a shead load of deco running within a Mod1 cert.

Dispite this the PP02 reduction issue was not covered on my Mod1 in any detail and I dont think this is uncommon.

ATB

Mark Chase

lizardland · 15th June 2007, 09:03

Quote: (Originally Posted by divelermentov)

even going only into marginal deco, lets say 10 minutes, it is still a deco obligation.

Maybe that's why it isn't taught to any extent. I really couldn't be arsed SCR'ing for a 10min deco, especially when you're going to be shallow for most of that time. If I had the bailout then for 10min I'd go OC. What's the point of using a more difficult system with more risk of cocking it up when I can just shove a reg in my gob. If it was to save gas e.g. because I'd a long horizontal distance to cover before the deco then that's different but I'd have thought such committing diving was outside the scope of Mod 1.

Fair enough, a load of Mod1 divers are going to go out and do deep/big deco dives straight off, that's their choice but it's beyond the scope of their training that they signed up to. But it isn't hard to work out what you need to know, get in the water and learn it.

Cheers,

Stuart

PeteS · 15th June 2007, 09:22

Quote: (Originally Posted by prharris)

Ours was the same with IANTD. I had the same instructor as Fin, and although we covered semi-closed from the POV of how to achieve it and practiced it, deco was not touched as the couse is a no deco course.

r
P

That's exactly what happened to me. It's a no deco course, so SCR is a "get out of jail free" card, that's all. No sums involved.

Drmike · 15th June 2007, 10:08

Quote: (Originally Posted by EBT)

Its not a MOD1 skill and Mike, sorry but you started that whole debate (incidentally, your standards are out of date).

Yes SCR is taught on MOD1 what isnt taught is SCR deco (apparently)

But what course its taught on doesnt chage my actual point re: doing courses v learning off the net- in liew of courses ,seeing as the OP was talking about deco dives. Substitue a 2 everywhere I wrote 1 and the argument stands.

Given that the huge majority of CCR mod1 only divers do deco dives do you think Scr deco should be mentioned during mod1 even just briefly? To me it seams kinda silly on one hand to impress on new ccr divers the mantra 'always know your ppo2' yet on the other to teach the SCR skill yet not mention how to 'always know your ppo2' when using it.

But hey what do I care, Im just a self publicist who clearly revels in bad self publicity LOL!

Plus Ive got a hot date tonight and ive washed and pruned all my white bits in hopeful anticipation

Drmike · 15th June 2007, 10:12

Quote: (Originally Posted by Mark Chase)

Mod 1 CCR air dill no deco (Unless decompresion procedures qualified on OC)

Which most of us are, so yes you can rack up a shead load of deco running within a Mod1 cert.

Dispite this the PP02 reduction issue was not covered on my Mod1 in any detail and I dont think this is uncommon.

do you think it should be?

do you think its better to learn from a course than off the net?

If the answer to both questions is yes - then we are in full agreement

Drmike · 15th June 2007, 10:15

Quote: (Originally Posted by divelermentov)

Mike - do i read your posts correctly to observe the ppo2 drop at a given venting ratio and than use the drop ppo2 % to adjust your Vr3 ?

yes

and adjust the vr3 a bit lower again to add conservation

Mark Chase · 15th June 2007, 11:13

Quote: (Originally Posted by Drmike)

do you think it should be?

do you think its better to learn from a course than off the net?

If the answer to both questions is yes - then we are in full agreement

You raise a good point, our instructor Paul we both classed as excellent. He spent time showing us things like how to strip and rebuild a solenoid and he covered things like pure 02 CCR which were not on the course.

However, we were taught semi closed at the most basic level and SCR decompression planning wasn't discussed but we all knew that the standards allowed us to carry out full decompression dives on the unit. What was discussed in detail was OC bailout planning

I remember doing Mod 3 with Paul and he said the mindset of Mod one was if in doubt bailout and that Mod 3 was all about expanding the option to stay on loop and planning deep bailout strategies.

As a result I don't see it as a big failing of my Mod1. I shouldn't be diving below 40m and as a result there was no excuse for having inadequate OC bailout.

ATB

Mark Chase

15th June 2007, 03:03	#31 (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: 3,300	Re: deco plan when running semiclosed Quote: (Originally Posted by tecdivertraining) . A more in-depth discussion should at least take place during the academic session of mod 1 training even if the diver is far away from making this dive having just passed their course. soon they may be thinking about hitting these depth without considering the bailout gas requirements. . Hey Matt, I fully agree. SCR bail is part of Mod1, my understanding from whats being reported here is its being taught in mod 1 without mention of the drop in ppo2 and subesequently how to use that info (re:future deco) to calc deco I think if this is the case its kinda dumb. We preach the ALWAYS KNOW YOUR PPO2 Yet we are teaching students to bail to semniclosed in mod1 and not to think about what they are breathing? not to be aware of how running semclosed effects their ppo2? I appreciate that a mod1 diver is fully saturated with new things to learn on their course but how does this sound:? During scr running on a mod1 course: Instructor: "Ok now look at your display, see how your loop ppo2 is stabalising at a ppo2 just below the ppo2 of the dil at this depth - in future you will use that drop to calculate deco should you have to do scr bail on a deco dive." Student: "Yeh but Im only MOD1 and noooo mod1 diver ever goes straight out and does deco dives after their course and will aways wait to do deco dives before they do mod2 or 3 so please dont tell me stuff I dont need to know ...meanwhile back at the ranch ps, organising a trip over soon __________________ 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 : 15th June 2007 at 03:07.
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15th June 2007, 06:17	#32 (permalink)
divelermentov Nutty dentist - uwdriller Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: Auckland Posts: 635	Re: deco plan when running semiclosed Quote: (Originally Posted by tecdivertraining) Mike I tend to agree with you that SCR mode should be covered more in-depth. My thinking on this is Mod 1 divers are usually certified to dive to around 40m. So here is the scenario: A diver plans a dive to 40m for 25min resulting in 10 min limited deco obligation (planed using v-planner using my personal config) if at the last minute of the dive they had to bailout that would result in an increase of runtime from 40min to 73 min. quite a big jump considering the amount of bailout gas some dives choose to carry and the stress that could be encountered. My personal requirements would call for around a 1000 liters of gas to complete that deco, that’s assuming its not a CO2 issue. So introducing SCR in this case could avoid a diver surfacing and missing all that required deco due to inefficient gas planning. Some of the divers I have had the pleasure of diving with have never even considered this eventuality and would have been faced with lengthy deco obligations with no reel understanding of decompression diving techniques. A more in-depth discussion should at least take place during the academic session of mod 1 training even if the diver is far away from making this dive having just passed their course. soon they may be thinking about hitting these depth without considering the bailout gas requirements. Just my two cents worth. this was exactly the scenario I was thinking of, even going only into marginal deco, lets say 10 minutes, it is still a deco obligation. Therefore my question how to calculate teh drop in po2. Sorry for causing such an emotionla discusson with regards to who does what training to what standard, wasn't my intend to obset people. My question was merly of practical nature how to determine which computer setting to use to allow for the ppo2 drop. Mike - do i read your posts correctly to observe the ppo2 drop at a given venting ratio and than use the drop ppo2 % to adjust your Vr3 ? __________________ May The Sorb Be With You
(Online)

15th June 2007, 08:46	#33 (permalink)
*EBT* Apprentice Luddite Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: UK, Brighton Posts: 1,994	Re: deco plan when running semiclosed Its already been posted, but for the sake of clarity; The FiO2 depends on drive gas, loop volume, dump ratio and Tidal volume. So in practise this means the drop in %O2 from the dil is diver and unit specific. Whats normally suggested is that people do a real dive, with real diluents and do SCR mode. You then watch your displays and build your own table of %O2 drop and use this with a deco package of your choice (or a complicator like a VR£). Its not a MOD1 skill and Mike, sorry but you started that whole debate (incidentally, your standards are out of date). This is also why people get nervous of hypoxic dils when you dont need them... they compromise your SCR capabilities from a deco perspective. /Zak __________________ Eagles May Soar, but weasels don't get sucked into jet engines! Rebreather World Terms of service Real diving t-shirts for real divers
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15th June 2007, 08:53	#34 (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: 2,693	Re: deco plan when running semiclosed Quote: (Originally Posted by OceanOpportunity) while I hate these online pissing matches, I think that DrMike's reference to Mod1 came from an assumption that the original poster should have received this scr bailout training in Mod1. Doing a little reading between the lines, it seems that the poster may not have completed any mod2 or mod3 level training, just 'mod1' with Leon, and posted a simple inquiry on how to address scr bailout deco calculations. for all intents and purposes, diving beyond a mod1 level of training without being trained probably isnt the best of ideas. For sake of answering the original question...if incurring a deco obligation of more time than can be adequately accounted for with a controlled scr ascent followed by OC decompression with what you are carrying, then its time to rethink the requirements for the dive..be it more OC, more training in scr bailout, or a computer configuration that sniffs the gas while in scr Mod 1 CCR air dill no deco (Unless decompresion procedures qualified on OC) Which most of us are, so yes you can rack up a shead load of deco running within a Mod1 cert. Dispite this the PP02 reduction issue was not covered on my Mod1 in any detail and I dont think this is uncommon. ATB Mark Chase __________________ 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 Last edited by Mark Chase : 15th June 2007 at 08:56.
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15th June 2007, 09:03	#35 (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: 1,302	Re: deco plan when running semiclosed Quote: (Originally Posted by divelermentov) even going only into marginal deco, lets say 10 minutes, it is still a deco obligation. Maybe that's why it isn't taught to any extent. I really couldn't be arsed SCR'ing for a 10min deco, especially when you're going to be shallow for most of that time. If I had the bailout then for 10min I'd go OC. What's the point of using a more difficult system with more risk of cocking it up when I can just shove a reg in my gob. If it was to save gas e.g. because I'd a long horizontal distance to cover before the deco then that's different but I'd have thought such committing diving was outside the scope of Mod 1. Fair enough, a load of Mod1 divers are going to go out and do deep/big deco dives straight off, that's their choice but it's beyond the scope of their training that they signed up to. But it isn't hard to work out what you need to know, get in the water and learn it. Cheers, Stuart __________________ 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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15th June 2007, 09:22	#36 (permalink)
PeteS Consent Issued! Current Rebreather/s: Inspiration Classic Inspiration Vision Other Rebreather/s: Join Date: Jun 2005 Location: New Zealand Posts: 531	Re: deco plan when running semiclosed Quote: (Originally Posted by prharris) Ours was the same with IANTD. I had the same instructor as Fin, and although we covered semi-closed from the POV of how to achieve it and practiced it, deco was not touched as the couse is a no deco course. r P That's exactly what happened to me. It's a no deco course, so SCR is a "get out of jail free" card, that's all. No sums involved. __________________ Pete S. http://www.steggle.co.nz Every silver lining has a cloud
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15th June 2007, 10:08	#37 (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: 3,300	Re: deco plan when running semiclosed Quote: (Originally Posted by EBT) Its not a MOD1 skill and Mike, sorry but you started that whole debate (incidentally, your standards are out of date). Yes SCR is taught on MOD1 what isnt taught is SCR deco (apparently) But what course its taught on doesnt chage my actual point re: doing courses v learning off the net- in liew of courses ,seeing as the OP was talking about deco dives. Substitue a 2 everywhere I wrote 1 and the argument stands. Given that the huge majority of CCR mod1 only divers do deco dives do you think Scr deco should be mentioned during mod1 even just briefly? To me it seams kinda silly on one hand to impress on new ccr divers the mantra 'always know your ppo2' yet on the other to teach the SCR skill yet not mention how to 'always know your ppo2' when using it. But hey what do I care, Im just a self publicist who clearly revels in bad self publicity LOL! Plus Ive got a hot date tonight and ive washed and pruned all my white bits in hopeful anticipation __________________ 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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15th June 2007, 10:12	#38 (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: 3,300	Re: deco plan when running semiclosed Quote: (Originally Posted by Mark Chase) Mod 1 CCR air dill no deco (Unless decompresion procedures qualified on OC) Which most of us are, so yes you can rack up a shead load of deco running within a Mod1 cert. Dispite this the PP02 reduction issue was not covered on my Mod1 in any detail and I dont think this is uncommon. do you think it should be? do you think its better to learn from a course than off the net? If the answer to both questions is yes - then we are in full agreement __________________ 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
(Offline)

15th June 2007, 10:15	#39 (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: 3,300	Re: deco plan when running semiclosed Quote: (Originally Posted by divelermentov) Mike - do i read your posts correctly to observe the ppo2 drop at a given venting ratio and than use the drop ppo2 % to adjust your Vr3 ? yes and adjust the vr3 a bit lower again to add conservation __________________ 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
(Offline)

15th June 2007, 11:13	#40 (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: 2,693	Re: deco plan when running semiclosed Quote: (Originally Posted by Drmike) do you think it should be? do you think its better to learn from a course than off the net? If the answer to both questions is yes - then we are in full agreement You raise a good point, our instructor Paul we both classed as excellent. He spent time showing us things like how to strip and rebuild a solenoid and he covered things like pure 02 CCR which were not on the course. However, we were taught semi closed at the most basic level and SCR decompression planning wasn't discussed but we all knew that the standards allowed us to carry out full decompression dives on the unit. What was discussed in detail was OC bailout planning I remember doing Mod 3 with Paul and he said the mindset of Mod one was if in doubt bailout and that Mod 3 was all about expanding the option to stay on loop and planning deep bailout strategies. As a result I don't see it as a big failing of my Mod1. I shouldn't be diving below 40m and as a result there was no excuse for having inadequate OC bailout. ATB Mark Chase __________________ 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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