Crossover Training

***jradomski*** · 16th March 2007, 02:35

Quote: (Originally Posted by Nick uk.)

I too only talked about SCR bailout in theory during my course, The school of thought being that it's a LAST resort when the sheet has really hit the fan and you've somehow managed to loose your 'adequate OC bailout' ..........

For a NO STOP REQUIRED dive this is an ok attitude to take, but once you get into mandatory stops, OC bailout should be the LAST thing you do, The bigger the required Deco, the longer you should run SCR.. The goal would be to stretch the OC reserves as far as possible, The way to do this is to either run the system manually (injecting oxygen) by monitoring an outside p2 display, or run SCR..

When the shit hits the fan you breathing rate is going to be much higher than norma, add to this that you have been using a rebreather for a long time, and your OC RMV goes to hell.. If your normal RMV was 14lpm on OC you need to at least double this.. Figure out your reserves and you'll quickly realize most CCR diver don't carry enough bailout to cover this for anything more than a short deco dive.

When properly trained and practiced, SCR is quite an easy skill and stretches the bailout supply tremendously.. Someone who does it right can routinely keep the po2 within .05-.1 of what a flush would be without any difficulties..

**wedivebc** · 16th March 2007, 02:51

Quote: (Originally Posted by jradomski)

For a NO STOP REQUIRED dive this is an ok attitude to take, but once you get into mandatory stops, OC bailout should be the LAST thing you do, The bigger the required Deco, the longer you should run SCR.. The goal would be to stretch the OC reserves as far as possible, The way to do this is to either run the system manually (injecting oxygen) by monitoring an outside p2 display, or run SCR..

When the shit hits the fan you breathing rate is going to be much higher than norma, add to this that you have been using a rebreather for a long time, and your OC RMV goes to hell.. If your normal RMV was 14lpm on OC you need to at least double this.. Figure out your reserves and you'll quickly realize most CCR diver don't carry enough bailout to cover this for anything more than a short deco dive.

When properly trained and practiced, SCR is quite an easy skill and stretches the bailout supply tremendously.. Someone who does it right can routinely keep the po2 within .05-.1 of what a flush would be without any difficulties..

The problem I see is how do you re-calculate your deco based on a SCR bailout (presumably your have lost PPO2 info) and you still need to carry full OC bailout in case loop integrity has failed. I don't want to speak for my instructor but this was the main objections he had for SCR bailout and they seem to make sense to me.

***jradomski*** · 16th March 2007, 03:11

Quote: (Originally Posted by sensor330)

All Inspiration divers that have converted to HH have been doing it years before the Optima was released without training and incident. I think that has a lot to say about the value one would get out of crossover training.

Scott

Scott,
I don;t agree with this at all.. The reason I originally wrote the HH manual is even though many of the first adopters of the HH were very experienced there were plenty of "issues" because people didn't understnad how things worked.. The manual was updated many times to answer the questions and give warnings on what can occur and why..

No matter how detailed the manual becomes, I can still give a 2-3 hours instruction on the HH electronics that even reading the manual several times wount do as well.. (not to mention the things I did not include in the manual)..

I can think of an incident several years ago (not sure if it was when the rev b or rev c boards first came out - I am think Rev B)

There was a certain well known Inspiration that was to take an Expedition trimix class in GC.. JM made sure that the upgraded handsets were in the diver's hands before the trip, and the manual was supposedly read several times before he received the electronics..

The diver gets to GC and tries to calibrate the Unit and Gets "Calibration Failed on cell XX".. The diver immediately tries moving cells around and sees no change on the cell reading 0.00.. Immediately complains his HH is all scewed up and started badmouthing it since he had to now uses a set of classic electronics and his cells were fine, the lowest being somewhere around an 8mv in air (this would clearly fail on the HH)

To make a long story short.. The HH was behaving as it should have and CLEARLY documented in the manual.. A cell that fails calibration is permanently displayed as 0.00 until a sucessful calibration.. You can move all the cells you want it will read 0.00 (Incidently the current Handset show FAIL)..

This was detailed in the manual,, It also told the user if they need to see if moving the cell effects things they need to use th mV screen.. It also clear tells the diver that the minimum mV needed in o2 is 40mv..

Over the years I have corresponded with more than one diver who said they read this but it didn't sink in.. On students I have taught how to use the HH no one has missed this point..

While many divers can get by with reading the manual, to get the most of of the unit requires putting alot of hours using the electronics or have someone show you the ropes.. Alot of dives just use it in its default configuration and gradually start playing with the functions.. 1 good "class" by an experienced instructor (or even an experienced diver that understands how to teach) can go a really long way, to utilize the unit to a much greater extent than just getting by with it..

***jradomski*** · 16th March 2007, 03:37

Quote: (Originally Posted by wedivebc)

The problem I see is how do you re-calculate your deco based on a SCR bailout (presumably your have lost PPO2 info) and you still need to carry full OC bailout in case loop integrity has failed. I don't want to speak for my instructor but this was the main objections he had for SCR bailout and they seem to make sense to me.

Calculating the requirements for SCR bailout is very easy.. Done correctly each time you flush its brought back very close to the equivalet of doing it on OC..

Everytime you change levels you make sure you do a thorough flush regardless if you are still "allowed" more breaths before the next flush..

Add in a small margin on the gas for OC.. This will vary on how good you are and what the gas is.. for someone plugging in a 50% mix at 21m, calculating each of the stops as a 45% oc mis gives good margin.. (I calculate for myself the same as using 50% since I practice this regulary and can keep it spot on), and just extend my 6m stop a bit for my margin..

On small dives carrying full bailout is easy, on big dives it is not (even in a team concept).. Add in elevated breathing rates and it become more likely that you will run into gas issues.. At the worse case SCR should be used when you are deep, since the small changes in po2 have very small effect on your deco (planing at oc) and give you a much needed safety net..

When I do a Technical rebreather class if my students can't keep the po2 within .1 of the expected flush for at least 30 minutes they dont pass the program.. period.. At the start they are usually a bit sloppy, but with practice they get it well within those goals..

Lets say, the person was now up to the 9m stop, with 50% as the SCR supply gas, even if they were only getting a flush of .85 (thats a .1 error) the mix is just under 45% and within the planning limits..

I can't accept an argument not to use SCR (On Stop required dives) when the loop is intact (electronics or not).. Lack of skill is not a viable reason nor is lack of understanding how to do it safely.. You should know how to use all the tools at your disposal.. On the deepest portions of the Dive you can REALLY extend your available reserve supply, especially if you plan it for a wider po2 drop (while deep) allowing you to extend the flush/refill ratios..

You will find that regardless of depth, at the same workload, the given decay rate for a number of breath is quite predictable.. (not real numbers just an example.. if it took you 5 breaths to drop .05 while swimming lightly, you could expect that 10 breaths will drop somewhere around .1, and 20 breath .2) at depth a drop of .2 might be perfectly acceptable (say you bailed onto a mix with 20% o2 at 60m and had a stop there starting with a 1.4 and decaying to a 1.2 is fine) and the difference in oxygen content is ONLY 3%, try your tables, the deco schedule is about the same..

If you had to stay 3 minutes at this depth you would not have probably even needed a dump/refil cycle.. assuming 14lpm on OC (a good reate for most divers under normal conditioons) you would have needed about 294 liters of gas for 3 minutes, on scr (assuming a total loop volume of 8l (reasonable)) your only using 56l of gas.. Do this for just a few stops and you built in considerable margin should you choose to switch to OC..

On no deco dives going OC is for most divers the surest way to safety..

**wedivebc** · 16th March 2007, 04:09

Quote: (Originally Posted by jradomski)

On small dives carrying full bailout is easy, on big dives it is not (even in a team concept).. Add in elevated breathing rates and it become more likely that you will run into gas issues..

So if you have a compromised loop you will not have adequate OC bailout?

Mike · 16th March 2007, 04:31

Quote: (Originally Posted by Steve)

Their previous instructor and their background is irrelevant in the process of showing me pre, in water and post dive skills.

Do you ever take it up with their previous Instructor when you have a student who is not up to your standards?
It's pretty well assumed that you will know their previous instructor - are you willing to publicly state which instructors have trained students who you later decide are not up to scratch?
Are you happy to dive with people trained by these instructors?

Ive stated my opinion on courses / crossovers before - I think the system is arse about face currently. The onus should be on the student to say that the instructor has taught them all they need to know, with an agency defined sylabus to enable the student to be aware of all the areas that should be covered. I don't want to spend time on a Meg course being judged as to whether I can hold a stop within 50cm for 20 minutes, I want to spend that time making sure that I can calibrate accurately every time and understanding how to fix problems like the head corrosion etc.

I think the 10c a minute payment for instruction would be great. Double it even! If I wanted instruction I'd happily pay $100 a day to have an instructor cover exactly the stuff I was interested in. Would be great value for money.

Mike

***jradomski*** · 16th March 2007, 04:50

Quote: (Originally Posted by wedivebc)

So if you have a compromised loop you will not have adequate OC bailout?

There are dives where I accept the fact that there is no way we can carry enough gas to get to safety completely on our own.. Just as decompression is a risk, a compromised loop is a risk as well..
Fortunately a completely useless loop is a rare thing, and odds are in the favor that this particular scenario wount happen especially of exra precautions are taken..

SCR is not a substite for having the absolute minimum gas needed for NORMAL conditions, its a way to allow you to extend the supplies that you have so that if other things come into play like stress or having to work hard you don't run out of gas.. for many dives its not feasible to have big margins and you just have to accept the risk or not do the dive..

If we could always carry enough gas to get us out of every situation, you wouldnt be seeing dives >100m with runtimes more than a few minutes.... Try and run some calculations doing even a dive to 100m for 30-40minutes, and see just how much gas is needed to safely complete the dive.. without a big team and running with absolute minimum margins the dives become impossible without staging gases.. and that means you need to be able to GET TO THE GASES, again, SCR is a way to help insure you can reach this extra supply..

In reality its quite hard to carry enough gas to cover all contingencies, running SCR mode for most failures gives you a greater margin for error..

To this day I have never seen a total loop failure (and I am not saying it cant happen, but the likihood is quite small, you probably have a much higher risk of getting bent and that doesnt stop you from deco diving does it??).. I have seen floods that compromised the loop but did not force immediate bailing onto OC.. I personally had an inspiration with a cannister that was about HALF flooded by the time the dive ended (the exhale lung was also pretty full but I got most of the water out of that (got there from dumping water from the cannister to the cl).. I was able to stay on the loop for a significant fortion of the deco, and had gas to spare at the end.. Knowing I had reserves went a long way in allowing me to stay calm and not have to worry about if I was going to have enough gas..

sensor330 · 16th March 2007, 05:28

Quote: (Originally Posted by jradomski)

Scott,
I don;t agree with this at all.. The reason I originally wrote the HH manual is even though many of the first adopters of the HH were very experienced there were plenty of "issues" because people didn't understnad how things worked.. The manual was updated many times to answer the questions and give warnings on what can occur and why..

No matter how detailed the manual becomes, I can still give a 2-3 hours instruction on the HH electronics that even reading the manual several times wount do as well.. (not to mention the things I did not include in the manual)..

I can think of an incident several years ago (not sure if it was when the rev b or rev c boards first came out - I am think Rev B)

There was a certain well known Inspiration that was to take an Expedition trimix class in GC.. JM made sure that the upgraded handsets were in the diver's hands before the trip, and the manual was supposedly read several times before he received the electronics..

The diver gets to GC and tries to calibrate the Unit and Gets "Calibration Failed on cell XX".. The diver immediately tries moving cells around and sees no change on the cell reading 0.00.. Immediately complains his HH is all scewed up and started badmouthing it since he had to now uses a set of classic electronics and his cells were fine, the lowest being somewhere around an 8mv in air (this would clearly fail on the HH)

To make a long story short.. The HH was behaving as it should have and CLEARLY documented in the manual.. A cell that fails calibration is permanently displayed as 0.00 until a sucessful calibration.. You can move all the cells you want it will read 0.00 (Incidently the current Handset show FAIL)..

This was detailed in the manual,, It also told the user if they need to see if moving the cell effects things they need to use th mV screen.. It also clear tells the diver that the minimum mV needed in o2 is 40mv..

Over the years I have corresponded with more than one diver who said they read this but it didn't sink in.. On students I have taught how to use the HH no one has missed this point..

While many divers can get by with reading the manual, to get the most of of the unit requires putting alot of hours using the electronics or have someone show you the ropes.. Alot of dives just use it in its default configuration and gradually start playing with the functions.. 1 good "class" by an experienced instructor (or even an experienced diver that understands how to teach) can go a really long way, to utilize the unit to a much greater extent than just getting by with it..

Correct me if I'm wrong but there is no such thing as a certification for a HH fitted to a Inspiration. My point being is in my case I believe I will get very little benefit out of any addition training on any more rebreathers.

***jradomski*** · 16th March 2007, 12:33

Quote: (Originally Posted by sensor330)

Correct me if I'm wrong but there is no such thing as a certification for a HH fitted to a Inspiration. My point being is in my case I believe I will get very little benefit out of any addition training on any more rebreathers.

Corrected...
I have issued several certifications to students I have trained so that they have no issues on boats that demand a certification or have insurance issues..

EVERYONE can get benefit from working with others.. It might not be the same as someone just starting out but exposure to other training methodologies can broaden a persons view..

Its much more efficient having someone share their experiences than one having to figure it out on their own.. I agree each class that you take there is less new material that would be learned, but they day we stop learning we might as well be dead..

**Dave Sutton** · 16th March 2007, 12:55

Quote: (Originally Posted by wedivebc)

So if you have a compromised loop you will not have adequate OC bailout?

The answer is "That's Right".

The follow on is "Why would you have a compromised loop?". Take care of the loop like your life depends on it *because it does* and leave that open circuit mindset at home. Total loop flood? Not.

(and have enough 02 in your diluent so it can be a decent SCC gas).

Dave

16th March 2007, 02:35	#41 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: Crossover Training Quote: (Originally Posted by Nick uk.) I too only talked about SCR bailout in theory during my course, The school of thought being that it's a LAST resort when the sheet has really hit the fan and you've somehow managed to loose your 'adequate OC bailout' .......... For a NO STOP REQUIRED dive this is an ok attitude to take, but once you get into mandatory stops, OC bailout should be the LAST thing you do, The bigger the required Deco, the longer you should run SCR.. The goal would be to stretch the OC reserves as far as possible, The way to do this is to either run the system manually (injecting oxygen) by monitoring an outside p2 display, or run SCR.. When the shit hits the fan you breathing rate is going to be much higher than norma, add to this that you have been using a rebreather for a long time, and your OC RMV goes to hell.. If your normal RMV was 14lpm on OC you need to at least double this.. Figure out your reserves and you'll quickly realize most CCR diver don't carry enough bailout to cover this for anything more than a short deco dive. When properly trained and practiced, SCR is quite an easy skill and stretches the bailout supply tremendously.. Someone who does it right can routinely keep the po2 within .05-.1 of what a flush would be without any difficulties.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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16th March 2007, 02:51	#42 (permalink)
wedivebc Dave Tomblin Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,508	Re: Crossover Training Quote: (Originally Posted by jradomski) For a NO STOP REQUIRED dive this is an ok attitude to take, but once you get into mandatory stops, OC bailout should be the LAST thing you do, The bigger the required Deco, the longer you should run SCR.. The goal would be to stretch the OC reserves as far as possible, The way to do this is to either run the system manually (injecting oxygen) by monitoring an outside p2 display, or run SCR.. When the shit hits the fan you breathing rate is going to be much higher than norma, add to this that you have been using a rebreather for a long time, and your OC RMV goes to hell.. If your normal RMV was 14lpm on OC you need to at least double this.. Figure out your reserves and you'll quickly realize most CCR diver don't carry enough bailout to cover this for anything more than a short deco dive. When properly trained and practiced, SCR is quite an easy skill and stretches the bailout supply tremendously.. Someone who does it right can routinely keep the po2 within .05-.1 of what a flush would be without any difficulties.. The problem I see is how do you re-calculate your deco based on a SCR bailout (presumably your have lost PPO2 info) and you still need to carry full OC bailout in case loop integrity has failed. I don't want to speak for my instructor but this was the main objections he had for SCR bailout and they seem to make sense to me. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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16th March 2007, 03:11	#43 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: Crossover Training Quote: (Originally Posted by sensor330) All Inspiration divers that have converted to HH have been doing it years before the Optima was released without training and incident. I think that has a lot to say about the value one would get out of crossover training. Scott Scott, I don;t agree with this at all.. The reason I originally wrote the HH manual is even though many of the first adopters of the HH were very experienced there were plenty of "issues" because people didn't understnad how things worked.. The manual was updated many times to answer the questions and give warnings on what can occur and why.. No matter how detailed the manual becomes, I can still give a 2-3 hours instruction on the HH electronics that even reading the manual several times wount do as well.. (not to mention the things I did not include in the manual).. I can think of an incident several years ago (not sure if it was when the rev b or rev c boards first came out - I am think Rev B) There was a certain well known Inspiration that was to take an Expedition trimix class in GC.. JM made sure that the upgraded handsets were in the diver's hands before the trip, and the manual was supposedly read several times before he received the electronics.. The diver gets to GC and tries to calibrate the Unit and Gets "Calibration Failed on cell XX".. The diver immediately tries moving cells around and sees no change on the cell reading 0.00.. Immediately complains his HH is all scewed up and started badmouthing it since he had to now uses a set of classic electronics and his cells were fine, the lowest being somewhere around an 8mv in air (this would clearly fail on the HH) To make a long story short.. The HH was behaving as it should have and CLEARLY documented in the manual.. A cell that fails calibration is permanently displayed as 0.00 until a sucessful calibration.. You can move all the cells you want it will read 0.00 (Incidently the current Handset show FAIL).. This was detailed in the manual,, It also told the user if they need to see if moving the cell effects things they need to use th mV screen.. It also clear tells the diver that the minimum mV needed in o2 is 40mv.. Over the years I have corresponded with more than one diver who said they read this but it didn't sink in.. On students I have taught how to use the HH no one has missed this point.. While many divers can get by with reading the manual, to get the most of of the unit requires putting alot of hours using the electronics or have someone show you the ropes.. Alot of dives just use it in its default configuration and gradually start playing with the functions.. 1 good "class" by an experienced instructor (or even an experienced diver that understands how to teach) can go a really long way, to utilize the unit to a much greater extent than just getting by with it.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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16th March 2007, 03:37	#44 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: Crossover Training Quote: (Originally Posted by wedivebc) The problem I see is how do you re-calculate your deco based on a SCR bailout (presumably your have lost PPO2 info) and you still need to carry full OC bailout in case loop integrity has failed. I don't want to speak for my instructor but this was the main objections he had for SCR bailout and they seem to make sense to me. Calculating the requirements for SCR bailout is very easy.. Done correctly each time you flush its brought back very close to the equivalet of doing it on OC.. Everytime you change levels you make sure you do a thorough flush regardless if you are still "allowed" more breaths before the next flush.. Add in a small margin on the gas for OC.. This will vary on how good you are and what the gas is.. for someone plugging in a 50% mix at 21m, calculating each of the stops as a 45% oc mis gives good margin.. (I calculate for myself the same as using 50% since I practice this regulary and can keep it spot on), and just extend my 6m stop a bit for my margin.. On small dives carrying full bailout is easy, on big dives it is not (even in a team concept).. Add in elevated breathing rates and it become more likely that you will run into gas issues.. At the worse case SCR should be used when you are deep, since the small changes in po2 have very small effect on your deco (planing at oc) and give you a much needed safety net.. When I do a Technical rebreather class if my students can't keep the po2 within .1 of the expected flush for at least 30 minutes they dont pass the program.. period.. At the start they are usually a bit sloppy, but with practice they get it well within those goals.. Lets say, the person was now up to the 9m stop, with 50% as the SCR supply gas, even if they were only getting a flush of .85 (thats a .1 error) the mix is just under 45% and within the planning limits.. I can't accept an argument not to use SCR (On Stop required dives) when the loop is intact (electronics or not).. Lack of skill is not a viable reason nor is lack of understanding how to do it safely.. You should know how to use all the tools at your disposal.. On the deepest portions of the Dive you can REALLY extend your available reserve supply, especially if you plan it for a wider po2 drop (while deep) allowing you to extend the flush/refill ratios.. You will find that regardless of depth, at the same workload, the given decay rate for a number of breath is quite predictable.. (not real numbers just an example.. if it took you 5 breaths to drop .05 while swimming lightly, you could expect that 10 breaths will drop somewhere around .1, and 20 breath .2) at depth a drop of .2 might be perfectly acceptable (say you bailed onto a mix with 20% o2 at 60m and had a stop there starting with a 1.4 and decaying to a 1.2 is fine) and the difference in oxygen content is ONLY 3%, try your tables, the deco schedule is about the same.. If you had to stay 3 minutes at this depth you would not have probably even needed a dump/refil cycle.. assuming 14lpm on OC (a good reate for most divers under normal conditioons) you would have needed about 294 liters of gas for 3 minutes, on scr (assuming a total loop volume of 8l (reasonable)) your only using 56l of gas.. Do this for just a few stops and you built in considerable margin should you choose to switch to OC.. On no deco dives going OC is for most divers the surest way to safety.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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16th March 2007, 04:09	#45 (permalink)
wedivebc Dave Tomblin Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,508	Re: Crossover Training Quote: (Originally Posted by jradomski) On small dives carrying full bailout is easy, on big dives it is not (even in a team concept).. Add in elevated breathing rates and it become more likely that you will run into gas issues.. So if you have a compromised loop you will not have adequate OC bailout? __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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16th March 2007, 04:31	#46 (permalink)
Mike Prism 'prentice Current Rebreather/s: Prism Topaz Other Rebreather/s: Inspiration Classic Evolution Join Date: Feb 2005 Location: Melbourne Posts: 332	Re: Crossover Training Quote: (Originally Posted by Steve) Their previous instructor and their background is irrelevant in the process of showing me pre, in water and post dive skills. Do you ever take it up with their previous Instructor when you have a student who is not up to your standards? It's pretty well assumed that you will know their previous instructor - are you willing to publicly state which instructors have trained students who you later decide are not up to scratch? Are you happy to dive with people trained by these instructors? Ive stated my opinion on courses / crossovers before - I think the system is arse about face currently. The onus should be on the student to say that the instructor has taught them all they need to know, with an agency defined sylabus to enable the student to be aware of all the areas that should be covered. I don't want to spend time on a Meg course being judged as to whether I can hold a stop within 50cm for 20 minutes, I want to spend that time making sure that I can calibrate accurately every time and understanding how to fix problems like the head corrosion etc. I think the 10c a minute payment for instruction would be great. Double it even! If I wanted instruction I'd happily pay $100 a day to have an instructor cover exactly the stuff I was interested in. Would be great value for money. Mike __________________ Open ....... Closed Mind ........ Loop
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16th March 2007, 04:50	#47 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: Crossover Training Quote: (Originally Posted by wedivebc) So if you have a compromised loop you will not have adequate OC bailout? There are dives where I accept the fact that there is no way we can carry enough gas to get to safety completely on our own.. Just as decompression is a risk, a compromised loop is a risk as well.. Fortunately a completely useless loop is a rare thing, and odds are in the favor that this particular scenario wount happen especially of exra precautions are taken.. SCR is not a substite for having the absolute minimum gas needed for NORMAL conditions, its a way to allow you to extend the supplies that you have so that if other things come into play like stress or having to work hard you don't run out of gas.. for many dives its not feasible to have big margins and you just have to accept the risk or not do the dive.. If we could always carry enough gas to get us out of every situation, you wouldnt be seeing dives >100m with runtimes more than a few minutes.... Try and run some calculations doing even a dive to 100m for 30-40minutes, and see just how much gas is needed to safely complete the dive.. without a big team and running with absolute minimum margins the dives become impossible without staging gases.. and that means you need to be able to GET TO THE GASES, again, SCR is a way to help insure you can reach this extra supply.. In reality its quite hard to carry enough gas to cover all contingencies, running SCR mode for most failures gives you a greater margin for error.. To this day I have never seen a total loop failure (and I am not saying it cant happen, but the likihood is quite small, you probably have a much higher risk of getting bent and that doesnt stop you from deco diving does it??).. I have seen floods that compromised the loop but did not force immediate bailing onto OC.. I personally had an inspiration with a cannister that was about HALF flooded by the time the dive ended (the exhale lung was also pretty full but I got most of the water out of that (got there from dumping water from the cannister to the cl).. I was able to stay on the loop for a significant fortion of the deco, and had gas to spare at the end.. Knowing I had reserves went a long way in allowing me to stay calm and not have to worry about if I was going to have enough gas.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated. Last edited by jradomski : 16th March 2007 at 13:32.
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16th March 2007, 05:28	#48 (permalink)
sensor330 RBW Member Current Rebreather/s: Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Join Date: Feb 2005 Location: Victoria, British Columbia, Canada Posts: 594	Re: Crossover Training Quote: (Originally Posted by jradomski) Scott, I don;t agree with this at all.. The reason I originally wrote the HH manual is even though many of the first adopters of the HH were very experienced there were plenty of "issues" because people didn't understnad how things worked.. The manual was updated many times to answer the questions and give warnings on what can occur and why.. No matter how detailed the manual becomes, I can still give a 2-3 hours instruction on the HH electronics that even reading the manual several times wount do as well.. (not to mention the things I did not include in the manual).. I can think of an incident several years ago (not sure if it was when the rev b or rev c boards first came out - I am think Rev B) There was a certain well known Inspiration that was to take an Expedition trimix class in GC.. JM made sure that the upgraded handsets were in the diver's hands before the trip, and the manual was supposedly read several times before he received the electronics.. The diver gets to GC and tries to calibrate the Unit and Gets "Calibration Failed on cell XX".. The diver immediately tries moving cells around and sees no change on the cell reading 0.00.. Immediately complains his HH is all scewed up and started badmouthing it since he had to now uses a set of classic electronics and his cells were fine, the lowest being somewhere around an 8mv in air (this would clearly fail on the HH) To make a long story short.. The HH was behaving as it should have and CLEARLY documented in the manual.. A cell that fails calibration is permanently displayed as 0.00 until a sucessful calibration.. You can move all the cells you want it will read 0.00 (Incidently the current Handset show FAIL).. This was detailed in the manual,, It also told the user if they need to see if moving the cell effects things they need to use th mV screen.. It also clear tells the diver that the minimum mV needed in o2 is 40mv.. Over the years I have corresponded with more than one diver who said they read this but it didn't sink in.. On students I have taught how to use the HH no one has missed this point.. While many divers can get by with reading the manual, to get the most of of the unit requires putting alot of hours using the electronics or have someone show you the ropes.. Alot of dives just use it in its default configuration and gradually start playing with the functions.. 1 good "class" by an experienced instructor (or even an experienced diver that understands how to teach) can go a really long way, to utilize the unit to a much greater extent than just getting by with it.. Correct me if I'm wrong but there is no such thing as a certification for a HH fitted to a Inspiration. My point being is in my case I believe I will get very little benefit out of any addition training on any more rebreathers.
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16th March 2007, 12:33	#49 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Join Date: Mar 2005 Location: "Da" Bronx Posts: 3,113	Re: Crossover Training Quote: (Originally Posted by sensor330) Correct me if I'm wrong but there is no such thing as a certification for a HH fitted to a Inspiration. My point being is in my case I believe I will get very little benefit out of any addition training on any more rebreathers. Corrected... I have issued several certifications to students I have trained so that they have no issues on boats that demand a certification or have insurance issues.. EVERYONE can get benefit from working with others.. It might not be the same as someone just starting out but exposure to other training methodologies can broaden a persons view.. Its much more efficient having someone share their experiences than one having to figure it out on their own.. I agree each class that you take there is less new material that would be learned, but they day we stop learning we might as well be dead.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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16th March 2007, 12:55	#50 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: Crossover Training Quote: (Originally Posted by wedivebc) So if you have a compromised loop you will not have adequate OC bailout? The answer is "That's Right". The follow on is "Why would you have a compromised loop?". Take care of the loop like your life depends on it because it does and leave that open circuit mindset at home. Total loop flood? Not. (and have enough 02 in your diluent so it can be a decent SCC gas). Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
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