OC/DSV - essential or toy? Multiple choice too!

wizbang · 21st August 2005, 22:12

I don't recall people saying, "I did a heap of flushing and I still needed to bail to the OC."
Trev Jackson doing the 170+m dive had some CO2 issues and flushed flushed flushed.
I am not saying that if he had an OC/DSV he wouldn't have used it but it shouldn't be your first option either.

Mdemon, It wasn't a personal critique of your system just pointing out that it can use an awfull lot of gas to clear a CO2 and calm down and the most OC/DSV's I have seen have all been to onboard only.

I have a number of friends relaying their CO2 hits etc, one that had an OC/DSV and couldn't get it turned on, the hit was so debilitating.

Some more clarity on the subject. (I crack myself up)

Scuba_Vixen · 21st August 2005, 22:14

Quote: (Originally Posted by decoweenie)

I had two students tested to 40+ LPM working RMV and thought that was high until last week-end, another student did 88 LPM working RMV.

I am not sure what he will need to carry for bail-out yet when he does the KISS course next week...

Is surface supplied and option .....

ROB DAVIE · 21st August 2005, 22:17

Quote: (Originally Posted by wizbang)

Trev Jackson doing the 170+m dive had some CO2 issues and flushed flushed flushed.
I am not saying that if he had an OC/DSV he wouldn't have used it but it shouldn't be your first option either.

Actually, it should be. Take a few sanity breaths, then analyze and deal with the problem. Your thinking qualities will be far better for it! Nothing precludes you from going back on the loop if it is your better course of action!

Cheers!

Rob

wizbang · 22nd August 2005, 00:32

Hi Rob, I am the type to get off the loop, get myself together and consider my options of getting back on or staying off. I plan to be able to get off and stay off from the worst point.
But coming from SCR I tend to flush first to check things out. It is why I added a manual add button very early on. (drawing through the ADV is ok but not as easy)

There are a number of people that consider the loop the proper place to be and that prudent and correct flushing will correct all but a decent flood. That is as long as you are paying attention to the system in the first place and it/you are not a runaway train.

jdz · 22nd August 2005, 01:16

Quote: (Originally Posted by nmanfield)

Got a nemotech and very impressed with it. I bougt mine just under a year ago and had no problems with receiving it. Filip kept in touch and was very helpful - received it in less than a month after ordering. The benefits I have found is that it leaks less than my orginal DSV and I find that when starting a dive I can completely empty the counterlungs, dive down on OC for the first few metres, then switch back to CC once I'm sinking (slightly lesser weight needed). I also go to OC when back on the surface as I don't have to monitor handsets when getting back on a rib.

I am prebreathing and carry out all checks prior to going under, I only go to OC for the first 2 metres. Anyone else with thoughts about this or am I doing something very stupid?

Hi nmanfield,

I'm not overly familiar with the seals on the Inspo, but I would have thought that there needs to be a caution here. The unit will be subjected to a considerable negative pressure, possibly allowing for water to flood into the unit.

Whilst looking at the alternative options for redundant Rbs, I would imaging that the unit needs to self inflate on the descent (and vent on ascent) and this keeps the unit at ambient pressure (not withstanding the bouyancy issues).

Finding units with seals that can withstand pressure could be an experiment to take on. Any thoughts??

Cheers, JDZ

wrecked · 22nd August 2005, 01:36

Quote: (Originally Posted by wizbang)

Hi Rob, I am the type to get off the loop, get myself together and consider my options of getting back on or staying off. I plan to be able to get off and stay off from the worst point.
But coming from SCR I tend to flush first to check things out. It is why I added a manual add button very early on. (drawing through the ADV is ok but not as easy)

There are a number of people that consider the loop the proper place to be and that prudent and correct flushing will correct all but a decent flood. That is as long as you are paying attention to the system in the first place and it/you are not a runaway train.

Hi Wiz

My first instinct is too grab the OC reg attached firmly around my neck or on my bottle . I think of using OC for safety first rather than trying to sort out of the problem. I still go back to my Mix training (It was a trying time with RT

) on OC when you were to have a reg in the mouth and breathing no matter what you were doing. I think of the same with an Rebreather, as long as I am still breathing I can survive and sort out the issue. This is the philosphy I intend to take into all of aspects of my diving.

If I flood I will try to cross back and manage to remove the excess, though if tasting a caustic flavour I think its time to say this aint coming back no matter what I do.

***schford*** · 22nd August 2005, 03:08

Whats wrong with Open Loop?

You dont have to turn anything and it saved DrMikes butt when all he could do was breath in through his mouth and out through his nose when he was laying on the floor unable to move....it is what Leon Scamahorn teaches from day one....

In effect it does exactly the same thing as an oc/cc and uses the ADV as your second stage...

Stuart

**Steve** · 22nd August 2005, 03:32

Quote: (Originally Posted by schford)

Whats wrong with Open Loop?

You dont have to turn anything and it saved DrMikes butt when all he could do was breath in through his mouth and out through his nose when he was laying on the floor unable to move....it is what Leon Scamahorn teaches from day one....

In effect it does exactly the same thing as an oc/cc and uses the ADV as your second stage...

Stuart

Hi Stuart,

the issue with open loop is that if one is incapacitated by a CO2 event then the debilitating effects of the hit may be such that this skill is quite hard to perform. Let’s say you suffer a hit anywhere but on the bottom; if one is diving with an OC/CC DSV and in the case of a hit you or your buddy turns you DSV to OC, then your buoyancy remains much more manageable than if you dump your loop and have to juggle your BC and loop volumes to hold a stop or prevent yourself from sinking to an undesirable depth. Another issue with the open loop method is that if the CO2 problem is being caused by your inhale flapper valve failing. Even with the most diligent flush you will still have CO2 laden gas in both sides of your loop. Not impossible to sort out but definitely tougher than an OC/CC DSV.

I guess that is the bottom line for this choice. There are other options to owning an OC/CC DSV. Plenty of divers get along fine without them. Having said that, I like to think of myself as a reasonably skilled CCR diver; I practice skills and do a lot of diving to stay as capable as I can in good diving practices. Now for the rub. Shit happens and I like being able to sort problems out as quickly and as easily as possible. I just can’t see any reason to not use one when they simplify the rectification of a potentially lethal issue.

wizbang · 22nd August 2005, 04:00

Quote: (Originally Posted by Steve)

Let’s say you suffer a hit anywhere but on the bottom; if one is diving with an OC/CC DSV and in the case of a hit you or your buddy turns you DSV to OC, then your buoyancy remains much more manageable than if you dump your loop and have to juggle your BC and loop volumes to hold a stop or prevent yourself from sinking to an undesirable depth.

If you are dumping, open loop style, then you will only be changing buoancy breath for breath. And I think that if the hit is that bad then the breaths might be pretty close together.

Quote:

Another issue with the open loop method is that if the CO2 problem is being caused by your inhale flapper valve failing. Even with the most diligent flush you will still have CO2 laden gas in both sides of your loop. Not impossible to sort out but definitely tougher than an OC/CC DSV.

A manual flush (I know the KISS dosn't come with one (well kinda)) will dilute the bag regardless of the flapper valves, combined with an open loop flushing (which is what I thought Trev did) would have to drop the CO2 levels to managaable. (unless, as stated above, it was a decent flood)

Quote:

I guess that is the bottom line for this choice. There are other options to owning an OC/CC DSV. Plenty of divers get along fine without them. Having said that, I like to think of myself as a reasonably skilled CCR diver; I practice skills and do a lot of diving to stay as capable as I can in good diving practices. Now for the rub. Shit happens and I like being able to sort problems out as quickly and as easily as possible. I just can’t see any reason to not use one when they simplify the rectification of a potentially lethal issue.

Once again, don't get me wrong, if I could get one for $500 Aus, it would be on in a split second, but I would like to think it wouldn't be my first port of call, even then. I guess I am just trying to show how I see it as not essential but very nice to have.

decoweenie · 22nd August 2005, 04:55

Quote: (Originally Posted by wizbang)

A manual flush (I know the KISS dosn't come with one (well kinda)

You could do a diluent flush easily on either KISS units using different techniques. And most people could reach the diluent-flush button (on ADV) on the SK as well.

21st August 2005, 22:12	#31 (permalink)
wizbang WEB MERMEN Current Rebreather/s: Inspiration Classic Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Vision Evolution Prism Topaz Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Perth Australia Posts: 385	I don't recall people saying, "I did a heap of flushing and I still needed to bail to the OC." Trev Jackson doing the 170+m dive had some CO2 issues and flushed flushed flushed. I am not saying that if he had an OC/DSV he wouldn't have used it but it shouldn't be your first option either. Mdemon, It wasn't a personal critique of your system just pointing out that it can use an awfull lot of gas to clear a CO2 and calm down and the most OC/DSV's I have seen have all been to onboard only. I have a number of friends relaying their CO2 hits etc, one that had an OC/DSV and couldn't get it turned on, the hit was so debilitating. Some more clarity on the subject. (I crack myself up)
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21st August 2005, 22:14	#32 (permalink)
Scuba_Vixen e/mCCR Dolphin Pilot Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: May 2005 Location: St. Croix USVI Posts: 557	Quote: (Originally Posted by decoweenie) I had two students tested to 40+ LPM working RMV and thought that was high until last week-end, another student did 88 LPM working RMV. I am not sure what he will need to carry for bail-out yet when he does the KISS course next week... Is surface supplied and option .....
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21st August 2005, 22:17	#33 (permalink)
ROB DAVIE Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: HOUSTON, REPUBLIC OF TEJAS Posts: 1,120	Quote: (Originally Posted by wizbang) Trev Jackson doing the 170+m dive had some CO2 issues and flushed flushed flushed. I am not saying that if he had an OC/DSV he wouldn't have used it but it shouldn't be your first option either. Actually, it should be. Take a few sanity breaths, then analyze and deal with the problem. Your thinking qualities will be far better for it! Nothing precludes you from going back on the loop if it is your better course of action! Cheers! Rob __________________ [SIZE=2]"CC Rebreathers will become a viable part of tech diving [U]WHEN PIGS FLY[/U]!!"--GI3[/SIZE]
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22nd August 2005, 00:32	#34 (permalink)
wizbang WEB MERMEN Current Rebreather/s: Inspiration Classic Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Vision Evolution Prism Topaz Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Perth Australia Posts: 385	Hi Rob, I am the type to get off the loop, get myself together and consider my options of getting back on or staying off. I plan to be able to get off and stay off from the worst point. But coming from SCR I tend to flush first to check things out. It is why I added a manual add button very early on. (drawing through the ADV is ok but not as easy) There are a number of people that consider the loop the proper place to be and that prudent and correct flushing will correct all but a decent flood. That is as long as you are paying attention to the system in the first place and it/you are not a runaway train.
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22nd August 2005, 01:16	#35 (permalink)
jdz Prism Cave Diver Current Rebreather/s: Prism Topaz Dolphin Home Build Other Rebreather/s: Dolphin Home Build Join Date: Feb 2005 Location: Melbourne Australia Posts: 217	Quote: (Originally Posted by nmanfield) Got a nemotech and very impressed with it. I bougt mine just under a year ago and had no problems with receiving it. Filip kept in touch and was very helpful - received it in less than a month after ordering. The benefits I have found is that it leaks less than my orginal DSV and I find that when starting a dive I can completely empty the counterlungs, dive down on OC for the first few metres, then switch back to CC once I'm sinking (slightly lesser weight needed). I also go to OC when back on the surface as I don't have to monitor handsets when getting back on a rib. I am prebreathing and carry out all checks prior to going under, I only go to OC for the first 2 metres. Anyone else with thoughts about this or am I doing something very stupid? Hi nmanfield, I'm not overly familiar with the seals on the Inspo, but I would have thought that there needs to be a caution here. The unit will be subjected to a considerable negative pressure, possibly allowing for water to flood into the unit. Whilst looking at the alternative options for redundant Rbs, I would imaging that the unit needs to self inflate on the descent (and vent on ascent) and this keeps the unit at ambient pressure (not withstanding the bouyancy issues). Finding units with seals that can withstand pressure could be an experiment to take on. Any thoughts?? Cheers, JDZ
(Offline)

22nd August 2005, 01:36	#36 (permalink)
wrecked Wrecked Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: May 2005 Location: Lilydale, Vic Posts: 24	Quote: (Originally Posted by wizbang) Hi Rob, I am the type to get off the loop, get myself together and consider my options of getting back on or staying off. I plan to be able to get off and stay off from the worst point. But coming from SCR I tend to flush first to check things out. It is why I added a manual add button very early on. (drawing through the ADV is ok but not as easy) There are a number of people that consider the loop the proper place to be and that prudent and correct flushing will correct all but a decent flood. That is as long as you are paying attention to the system in the first place and it/you are not a runaway train. Hi Wiz My first instinct is too grab the OC reg attached firmly around my neck or on my bottle . I think of using OC for safety first rather than trying to sort out of the problem. I still go back to my Mix training (It was a trying time with RT ) on OC when you were to have a reg in the mouth and breathing no matter what you were doing. I think of the same with an Rebreather, as long as I am still breathing I can survive and sort out the issue. This is the philosphy I intend to take into all of aspects of my diving. If I flood I will try to cross back and manage to remove the excess, though if tasting a caustic flavour I think its time to say this aint coming back no matter what I do.
(Offline)

22nd August 2005, 03:08	#37 (permalink)
*schford* Despotic Overlord Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: London, UK Posts: 3,674	Whats wrong with Open Loop? You dont have to turn anything and it saved DrMikes butt when all he could do was breath in through his mouth and out through his nose when he was laying on the floor unable to move....it is what Leon Scamahorn teaches from day one.... In effect it does exactly the same thing as an oc/cc and uses the ADV as your second stage... Stuart
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22nd August 2005, 03:32	#38 (permalink)
Steve Ladies bring a plate Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Classic Kiss MK 15.X Home Build Join Date: Feb 2005 Location: Perth - Australia Posts: 1,103	Quote: (Originally Posted by schford) Whats wrong with Open Loop? You dont have to turn anything and it saved DrMikes butt when all he could do was breath in through his mouth and out through his nose when he was laying on the floor unable to move....it is what Leon Scamahorn teaches from day one.... In effect it does exactly the same thing as an oc/cc and uses the ADV as your second stage... Stuart Hi Stuart, the issue with open loop is that if one is incapacitated by a CO2 event then the debilitating effects of the hit may be such that this skill is quite hard to perform. Let’s say you suffer a hit anywhere but on the bottom; if one is diving with an OC/CC DSV and in the case of a hit you or your buddy turns you DSV to OC, then your buoyancy remains much more manageable than if you dump your loop and have to juggle your BC and loop volumes to hold a stop or prevent yourself from sinking to an undesirable depth. Another issue with the open loop method is that if the CO2 problem is being caused by your inhale flapper valve failing. Even with the most diligent flush you will still have CO2 laden gas in both sides of your loop. Not impossible to sort out but definitely tougher than an OC/CC DSV. I guess that is the bottom line for this choice. There are other options to owning an OC/CC DSV. Plenty of divers get along fine without them. Having said that, I like to think of myself as a reasonably skilled CCR diver; I practice skills and do a lot of diving to stay as capable as I can in good diving practices. Now for the rub. Shit happens and I like being able to sort problems out as quickly and as easily as possible. I just can’t see any reason to not use one when they simplify the rectification of a potentially lethal issue. __________________ WARNING: I contain occasional coarse language, extreme sexual references, nudity, and adult themes, which may offend some people - Usually churchy types.
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22nd August 2005, 04:00	#39 (permalink)
wizbang WEB MERMEN Current Rebreather/s: Inspiration Classic Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Vision Evolution Prism Topaz Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Perth Australia Posts: 385	Quote: (Originally Posted by Steve) Let’s say you suffer a hit anywhere but on the bottom; if one is diving with an OC/CC DSV and in the case of a hit you or your buddy turns you DSV to OC, then your buoyancy remains much more manageable than if you dump your loop and have to juggle your BC and loop volumes to hold a stop or prevent yourself from sinking to an undesirable depth. If you are dumping, open loop style, then you will only be changing buoancy breath for breath. And I think that if the hit is that bad then the breaths might be pretty close together. Quote: Another issue with the open loop method is that if the CO2 problem is being caused by your inhale flapper valve failing. Even with the most diligent flush you will still have CO2 laden gas in both sides of your loop. Not impossible to sort out but definitely tougher than an OC/CC DSV. A manual flush (I know the KISS dosn't come with one (well kinda)) will dilute the bag regardless of the flapper valves, combined with an open loop flushing (which is what I thought Trev did) would have to drop the CO2 levels to managaable. (unless, as stated above, it was a decent flood) Quote: I guess that is the bottom line for this choice. There are other options to owning an OC/CC DSV. Plenty of divers get along fine without them. Having said that, I like to think of myself as a reasonably skilled CCR diver; I practice skills and do a lot of diving to stay as capable as I can in good diving practices. Now for the rub. Shit happens and I like being able to sort problems out as quickly and as easily as possible. I just can’t see any reason to not use one when they simplify the rectification of a potentially lethal issue. Once again, don't get me wrong, if I could get one for $500 Aus, it would be on in a split second, but I would like to think it wouldn't be my first port of call, even then. I guess I am just trying to show how I see it as not essential but very nice to have.
(Offline)

22nd August 2005, 04:55	#40 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,510	Quote: (Originally Posted by wizbang) A manual flush (I know the KISS dosn't come with one (well kinda) You could do a diluent flush easily on either KISS units using different techniques. And most people could reach the diluent-flush button (on ADV) on the SK as well. __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
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