To BOV or not BOV - Split From NACD Cave Summit

Mark Chase · 23rd November 2007, 21:08

More on the Bov issue please and keep us posted when the video is ready.

ATB

Mark

netmage · 23rd November 2007, 22:09

In his discussions (multiple times over the weekend) Brett Hemphill was quite adamant on the value of the BOV for the instantaneous ability to get off the loop.

I think a significant part of the 'con' argument presented by the panel 'should' be a non-issue in practical application. The argument was against having a BOV because on-board gas provides relatively little 'bailout' opportunity.... Perhaps I'm being naive, I would assume a BOV should be plumbed to Off-board gas? Of course everyone's failure example is at 300' or 6000' feet back in a cave.... where on-board gas supplies may litterally only provide one or two 'sanity breaths'....

-Tim

RonMicjan · 23rd November 2007, 22:51

Quote: (Originally Posted by netmage)

In his discussions (multiple times over the weekend) Brett Hemphill was quite adamant on the value of the BOV for the instantaneous ability to get off the loop.

I think a significant part of the 'con' argument presented by the panel 'should' be a non-issue in practical application. The argument was against having a BOV because on-board gas provides relatively little 'bailout' opportunity.... Perhaps I'm being naive, I would assume a BOV should be plumbed to Off-board gas? Of course everyone's failure example is at 300' or 6000' feet back in a cave.... where on-board gas supplies may litterally only provide one or two 'sanity breaths'....

-Tim

I would like to get my hands on the video of the event, Jill is an excellent hostess and entertaining speaker.

On the BOV question... Sorry in advance for the hijack...
At any given time the BOV can only be plumbed into one gas, so which gas do you plumb it into? On board, where you only have a few breaths before you are gasping again? The only thing worse than running out of gas on a dive....is running out twice, just when you thought you were safe.

Off board, sure, what which offboard? Deep bailout? Great for most of the dive, but if using trimix, it could be very bad near the surface, obviously not plumbed into a rich mix, which would be just as bad if switched to it deep.

The best solution was done by Bill Stone on the Cis mk5, where the gas block allowed the diver to access any onboard or offboard gas directly to the BOV, but the diver must keep track of which gas the BOV is plumbed to and change it at the appropriate depth, so the correct gas would be available when the knob was turned.

Specifically on the Meg, the suggested bailout method is to do a dil flush using on board gas, breathe it open loop while deploying the appropriate off board bailout. This, of course, does not address whether the onboard dil is usefull for the entire dive, but one would expect that a seasoned mix diver would use the ADV for the flush at depth and the O2 add for a flush at less than 30fsw. At least the diver is trained that the onboard is a temporary fix.

Using a FFM complicates things even more, as there are plumbing limitations using specifically the Panarama mask.

One soulution I have seen is to put a QC on the input of the DSV, properly label your off board gasses and make swapping the feed lines part of your decent and ascent procedure. This seems to be the best overall solution IMHO, but does require disipline on the part of the diver to swap the hoses at the correct times. Hmmm, maybe an automatic valve that switches the input gas based on depth! Calling John Routley... Bill Stone...

And now, back to our regularly scheduled thread.

***ScubaDadMiami*** · 23rd November 2007, 23:27

Thanks for the write up on the Conference. Have some green.

One of the issues I have been told about regarding the BOV is that it is not a solution in the event of a heavy caustic cocktail. Even so, I still like having the option for all cases but the caustic cocktail. In that rare instance (which is made even more rare for me through use of the Extend Air Cartridge), I will deal with going directly to my offboard gas. This is a skill that I still regularly practice.

My solution to the small gas volume is to carry larger onboard tanks. This is why I have not elected to use the smaller tanks that most rebreather divers use.

***caveseeker7*** · 23rd November 2007, 23:45

Well, if you use multiple gases the BOV obviously must be plugged into the correct one. Same is true for the ADV if you have one. Just having an additional port in the counterlung doesn't suffice IMHO.

Am curious how C2R is going to handle the BOV they've just shown on the Sentinel in the Stage 3 Version (which includes offboard gas connectors) and the Ouroboros. IIRC, the Ouroboros already includes the ADV/solenoid in the gas switch.

Joe, Mark, how is this handled in the new Hammerhead CCR?
The manifolds look like they can handle offboard gas to all sources.

mattmexico · 24th November 2007, 02:11

yo

Some thoughts about the Bail Out Valve ( BOV )

Signs and symptoms of Hypercapnia may include warm fuzzy cotton mouth feeling, slight feeling of something is not right, with slightly elevated breathing. When going to oc the warm fuzzy cotton mouth feeling went away almost immediately. I have witnessed a couple of o/c bailouts of other divers who have thought they may broke through and did not hesitate to bail out to o/c, not giving it a second thought.

It has happened that a diver managed to get in the water without co2 absorbent in his unit, despite checklist and all that. At they went down the shot line at about 20 feet the diver was breathing uncontrolled due to exertion and higher pco2. The dive partner realized what is going on and urged the student to switch to o/c. The unit was not equipped with a BOV. The diver was not able to make the switch as he was not able to hold his breath for even a split second to do the switch over. They went to the surface and they lived to tell the story.

I believe that if I decide to go off my CCR then I am off and want to go to something that is not connected, at all, to my CCR. Most BOV are connected to the inboard tank. I have seen some divers who had there BOV plumed via disconnect into their o/c bailout stage tank and this way going onto your BOV, this way keeping your mouthpiece in your mouth to do a easy switch over and yet go off your CCR onto a separate tank.

However, if you get into a situation where you for what ever reason really have to hand over your stage tank then you loose your own redundancy. Something else I have witnessed with BOV equipped divers is that they do not think about what gas they have in their BOV supply tank and use the BOV freely on the surface, and why not. It is that I just always imagine as they go on with their diving career and coming to trimix diving that bad habit will have them killed on the surface, due to hypoxia breathing a low o2 content mix on the surface and exerting. As one habit might be good in one diving situation and may kill you in another.

After hearing from the story of a diver not being able to get off the mouthpiece to do the switch over when he wanted and needed to, but physically was not able to do so the BOV seems like a life saver. Deep diving come to mind with higher pco2's and a faster need to switch over. When using a BOV connected to the inboard tank and the need to bailout arises, use your BOV. But as it is connected to your smaller inboard tank, it is just a step in-between.

Take a breath or three then go on to your o/c bailout stage, which is a completely separate life support system with recalculated po2 and gas volume and you know it’s going to work. When doing that last switch over to your complete detached and separate gas supply, you as well have decided you are not going back onto the CCR as you have decided you do not trust it anymore, other then providing buoyancy. And you stick with it.

And while you at it change your set point to a low one and open the over pressurization valve from your counter lungs as you will go up. The BOV could be a life saver if used properly.

What I have witnessed over and over again is that divers do hesitate to long, way toooo loooong before they decide to go to o/c ( SCR or CCR ) bailout when they think something is not right. They start thinking about it, are not sure, they feel something is or were not right, don't want to be embarrassed or other reasons. If you just think about o/c bailout and can not even put your finger on what or why, that very thought of just thinking about bailout is the very reason to bail out, now, do not hesitate a split second and go to o/c bailout, because that might have been your last chance to do so ... BOV or not ...

Mixaddict · 24th November 2007, 04:15

Mattmexico,

I agree wtih your thoughts about bailout 100%. Why on earth wouldn't you want to have that little extra % of chance to go to bailout using BOV if you had it? Sure, they seam clunky, large and get in the way, but what the heck, everything we wear with CCR could be decribed that way! The new Sentinel I have ordered has a BOV, and I am just waiting for the Inspo BOV to be available so that I can order one for that as well. I just don't see a down side. As you mentioned, the BOV will most likely be plumbed into the small internal tank, but is all I need is 2 or 3 or 4 sanity breaths, and I can switch to my outboard dil or O2 tank, depending on depth, and make my way back to the surface, if I determine that is the correct course of action. Have some green.

Your thoughs just make way too much sense!

Regards,
Randy

decoweenie · 24th November 2007, 05:13

Quote: (Originally Posted by w ripley)

Lamar Hires presented the Optima and NitekX computer
Leon Scamahorn the Megalodon
Brett Hemphill the KISS
John Conway the Inspiration Vision and Evolution
Jarrod Jablonski the RB80
Jakub Rehacek the Juergensen Marine Hammerhead CCR, and
Vince Ferris the MK15 and Lar5.

Quote: (Originally Posted by netmage)

In his discussions (multiple times over the weekend) Brett Hemphill was quite adamant on the value of the BOV for the instantaneous ability to get off the loop.

I think the minority of current manufacturers are on the "con" side:

Optima
Meg

IMHO, their production limitation probably affecting their view of providing a BOV with their unit.

The majority are on the "pro" side:

KISS (unit supplied with BOV)
APD (coming out with BOV)
Rebreather-80 (unit supplied with BOV)
HH CCR (unit supplied with BOV)

Non-production or O2 units:

MK-15
LAR-V

heyydude · 24th November 2007, 05:37

As I've said before on this forum, I'm alive today (as are both my children, I hasten to add) because I had Tracy Robinette's BOV on my AGA mask in 1996 off Catalina Island at 260 fsw.

When we were contemplating building our own rig, a BOV was without question a necessity, as a "standard" feature.

True, I had no personal compunction to try and use it to save my own life (John McKenney switched me over during a massive hypercapnia incident), but save my life it did. And if you take the time (like we did, back in the old days) and "train" your buddies on what gear you are diving (and make them dive similar, if not same gear) then all of you as a "team" understand what to do in the event of an emergency, then you have a much better chance of surviving an incident like I encountered.

Jakub's BOV is an fantastic evolution of a very good concept - giving a diver an easy way to switch from CC to OC with the flick of a lever, without having to abandon his DSV and search for a 2nd stage.

That is why, on every Hammerhead CCR we sell, his BOV is standard equipment.

Take care,

Kevin Juergensen
Juergensen Marine, Inc.

**wedivebc** · 24th November 2007, 14:25

Quote: (Originally Posted by mattmexico)

. If you just think about o/c bailout and can not even put your finger on what or why, that very thought of just thinking about bailout is the very reason to bail out, now, do not hesitate a split second and go to o/c bailout, because that might have been your last chance to do so ... BOV or not ...

There is a definate pearl of wisdom!

23rd November 2007, 21:08	#1 (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: 2,410	Re: CCR Cave Summit - NACD More on the Bov issue please and keep us posted when the video is ready. 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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23rd November 2007, 22:09	#2 (permalink)
netmage Hello Kitty...... Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Dec 2005 Location: Coconut Creek, FL Posts: 321	Re: CCR Cave Summit - NACD In his discussions (multiple times over the weekend) Brett Hemphill was quite adamant on the value of the BOV for the instantaneous ability to get off the loop. I think a significant part of the 'con' argument presented by the panel 'should' be a non-issue in practical application. The argument was against having a BOV because on-board gas provides relatively little 'bailout' opportunity.... Perhaps I'm being naive, I would assume a BOV should be plumbed to Off-board gas? Of course everyone's failure example is at 300' or 6000' feet back in a cave.... where on-board gas supplies may litterally only provide one or two 'sanity breaths'.... -Tim
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23rd November 2007, 22:51	#3 (permalink)
RonMicjan Cap Ron scourge of the NW Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Cape Disapointment, The Graveyard of the Pacific Posts: 1,081	Re: CCR Cave Summit - NACD Quote: (Originally Posted by netmage) In his discussions (multiple times over the weekend) Brett Hemphill was quite adamant on the value of the BOV for the instantaneous ability to get off the loop. I think a significant part of the 'con' argument presented by the panel 'should' be a non-issue in practical application. The argument was against having a BOV because on-board gas provides relatively little 'bailout' opportunity.... Perhaps I'm being naive, I would assume a BOV should be plumbed to Off-board gas? Of course everyone's failure example is at 300' or 6000' feet back in a cave.... where on-board gas supplies may litterally only provide one or two 'sanity breaths'.... -Tim I would like to get my hands on the video of the event, Jill is an excellent hostess and entertaining speaker. On the BOV question... Sorry in advance for the hijack... At any given time the BOV can only be plumbed into one gas, so which gas do you plumb it into? On board, where you only have a few breaths before you are gasping again? The only thing worse than running out of gas on a dive....is running out twice, just when you thought you were safe. Off board, sure, what which offboard? Deep bailout? Great for most of the dive, but if using trimix, it could be very bad near the surface, obviously not plumbed into a rich mix, which would be just as bad if switched to it deep. The best solution was done by Bill Stone on the Cis mk5, where the gas block allowed the diver to access any onboard or offboard gas directly to the BOV, but the diver must keep track of which gas the BOV is plumbed to and change it at the appropriate depth, so the correct gas would be available when the knob was turned. Specifically on the Meg, the suggested bailout method is to do a dil flush using on board gas, breathe it open loop while deploying the appropriate off board bailout. This, of course, does not address whether the onboard dil is usefull for the entire dive, but one would expect that a seasoned mix diver would use the ADV for the flush at depth and the O2 add for a flush at less than 30fsw. At least the diver is trained that the onboard is a temporary fix. Using a FFM complicates things even more, as there are plumbing limitations using specifically the Panarama mask. One soulution I have seen is to put a QC on the input of the DSV, properly label your off board gasses and make swapping the feed lines part of your decent and ascent procedure. This seems to be the best overall solution IMHO, but does require disipline on the part of the diver to swap the hoses at the correct times. Hmmm, maybe an automatic valve that switches the input gas based on depth! Calling John Routley... Bill Stone... And now, back to our regularly scheduled thread. __________________ Ron "Life is pain princess, anyone who tells you different, is selling something", The Dread Pirate Wesley. www.tmishop.com Diving bits etc.
(Offline)

23rd November 2007, 23:27	#4 (permalink)
*ScubaDadMiami* Moderator Current Rebreather/s: Optima Other Rebreather/s: Join Date: Sep 2005 Location: Florida, USA Posts: 1,890	Re: CCR Cave Summit - NACD Thanks for the write up on the Conference. Have some green. One of the issues I have been told about regarding the BOV is that it is not a solution in the event of a heavy caustic cocktail. Even so, I still like having the option for all cases but the caustic cocktail. In that rare instance (which is made even more rare for me through use of the Extend Air Cartridge), I will deal with going directly to my offboard gas. This is a skill that I still regularly practice. My solution to the small gas volume is to carry larger onboard tanks. This is why I have not elected to use the smaller tanks that most rebreather divers use. __________________ Howard Packer IANTD CCR Instructor Miami Beach, Florida CCRDiveTraining.com
(Offline)

23rd November 2007, 23:45	#5 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,284	Re: BOV & gases Well, if you use multiple gases the BOV obviously must be plugged into the correct one. Same is true for the ADV if you have one. Just having an additional port in the counterlung doesn't suffice IMHO. Am curious how C2R is going to handle the BOV they've just shown on the Sentinel in the Stage 3 Version (which includes offboard gas connectors) and the Ouroboros. IIRC, the Ouroboros already includes the ADV/solenoid in the gas switch. Joe, Mark, how is this handled in the new Hammerhead CCR? The manifolds look like they can handle offboard gas to all sources. __________________ Cheers Stefan Be Water, My Friend - Bruce Lee Sponsor Lou in Race For Life!
(Offline)

24th November 2007, 02:11	#6 (permalink)
mattmexico Rebreather World Writer Current Rebreather/s: Megalodon Classic Kiss Optima RB80 / Clone Other Rebreather/s: Inspiration Classic Evolution Prism Topaz Sport Kiss RB80 / Clone Join Date: Aug 2005 Location: Mexico, Q.Roo, Playa del Carmen Posts: 696	Re: CCR Cave Summit - NACD yo Some thoughts about the Bail Out Valve ( BOV ) Signs and symptoms of Hypercapnia may include warm fuzzy cotton mouth feeling, slight feeling of something is not right, with slightly elevated breathing. When going to oc the warm fuzzy cotton mouth feeling went away almost immediately. I have witnessed a couple of o/c bailouts of other divers who have thought they may broke through and did not hesitate to bail out to o/c, not giving it a second thought. It has happened that a diver managed to get in the water without co2 absorbent in his unit, despite checklist and all that. At they went down the shot line at about 20 feet the diver was breathing uncontrolled due to exertion and higher pco2. The dive partner realized what is going on and urged the student to switch to o/c. The unit was not equipped with a BOV. The diver was not able to make the switch as he was not able to hold his breath for even a split second to do the switch over. They went to the surface and they lived to tell the story. I believe that if I decide to go off my CCR then I am off and want to go to something that is not connected, at all, to my CCR. Most BOV are connected to the inboard tank. I have seen some divers who had there BOV plumed via disconnect into their o/c bailout stage tank and this way going onto your BOV, this way keeping your mouthpiece in your mouth to do a easy switch over and yet go off your CCR onto a separate tank. However, if you get into a situation where you for what ever reason really have to hand over your stage tank then you loose your own redundancy. Something else I have witnessed with BOV equipped divers is that they do not think about what gas they have in their BOV supply tank and use the BOV freely on the surface, and why not. It is that I just always imagine as they go on with their diving career and coming to trimix diving that bad habit will have them killed on the surface, due to hypoxia breathing a low o2 content mix on the surface and exerting. As one habit might be good in one diving situation and may kill you in another. After hearing from the story of a diver not being able to get off the mouthpiece to do the switch over when he wanted and needed to, but physically was not able to do so the BOV seems like a life saver. Deep diving come to mind with higher pco2's and a faster need to switch over. When using a BOV connected to the inboard tank and the need to bailout arises, use your BOV. But as it is connected to your smaller inboard tank, it is just a step in-between. Take a breath or three then go on to your o/c bailout stage, which is a completely separate life support system with recalculated po2 and gas volume and you know it’s going to work. When doing that last switch over to your complete detached and separate gas supply, you as well have decided you are not going back onto the CCR as you have decided you do not trust it anymore, other then providing buoyancy. And you stick with it. And while you at it change your set point to a low one and open the over pressurization valve from your counter lungs as you will go up. The BOV could be a life saver if used properly. What I have witnessed over and over again is that divers do hesitate to long, way toooo loooong before they decide to go to o/c ( SCR or CCR ) bailout when they think something is not right. They start thinking about it, are not sure, they feel something is or were not right, don't want to be embarrassed or other reasons. If you just think about o/c bailout and can not even put your finger on what or why, that very thought of just thinking about bailout is the very reason to bail out, now, do not hesitate a split second and go to o/c bailout, because that might have been your last chance to do so ... BOV or not ... __________________ N 20' 37.617' W 87' 04.693' www.andreaswmatthes.com
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24th November 2007, 04:15	#7 (permalink)
Mixaddict Always Learning! Current Rebreather/s: Inspiration Vision Evolution Other CCR Dolphin Other Rebreather/s: Inspiration Classic Other CCR Dolphin Join Date: Jan 2006 Location: Draper, Utah USA Posts: 415	Re: CCR Cave Summit - NACD Mattmexico, I agree wtih your thoughts about bailout 100%. Why on earth wouldn't you want to have that little extra % of chance to go to bailout using BOV if you had it? Sure, they seam clunky, large and get in the way, but what the heck, everything we wear with CCR could be decribed that way! The new Sentinel I have ordered has a BOV, and I am just waiting for the Inspo BOV to be available so that I can order one for that as well. I just don't see a down side. As you mentioned, the BOV will most likely be plumbed into the small internal tank, but is all I need is 2 or 3 or 4 sanity breaths, and I can switch to my outboard dil or O2 tank, depending on depth, and make my way back to the surface, if I determine that is the correct course of action. Have some green. Your thoughs just make way too much sense! Regards, Randy __________________ Randy Thornton (MixAddict) Inspiration, Evolution,Hammerhead & Sentinel CCR Instructor
(Online)

24th November 2007, 05:13	#8 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,509	Re: CCR Cave Summit - NACD Quote: (Originally Posted by w ripley) Lamar Hires presented the Optima and NitekX computer Leon Scamahorn the Megalodon Brett Hemphill the KISS John Conway the Inspiration Vision and Evolution Jarrod Jablonski the RB80 Jakub Rehacek the Juergensen Marine Hammerhead CCR, and Vince Ferris the MK15 and Lar5. Quote: (Originally Posted by netmage) In his discussions (multiple times over the weekend) Brett Hemphill was quite adamant on the value of the BOV for the instantaneous ability to get off the loop. I think the minority of current manufacturers are on the "con" side: Optima Meg IMHO, their production limitation probably affecting their view of providing a BOV with their unit. The majority are on the "pro" side: KISS (unit supplied with BOV) APD (coming out with BOV) Rebreather-80 (unit supplied with BOV) HH CCR (unit supplied with BOV) Non-production or O2 units: MK-15 LAR-V
(Offline)

24th November 2007, 05:37	#9 (permalink)
heyydude King of the Geeks Current Rebreather/s: MK 15.X Optima Other CCR Other Rebreather/s: Other CCR Join Date: May 2005 Location: Addison, Pennsylvania Posts: 319	Re: CCR Cave Summit - NACD As I've said before on this forum, I'm alive today (as are both my children, I hasten to add) because I had Tracy Robinette's BOV on my AGA mask in 1996 off Catalina Island at 260 fsw. When we were contemplating building our own rig, a BOV was without question a necessity, as a "standard" feature. True, I had no personal compunction to try and use it to save my own life (John McKenney switched me over during a massive hypercapnia incident), but save my life it did. And if you take the time (like we did, back in the old days) and "train" your buddies on what gear you are diving (and make them dive similar, if not same gear) then all of you as a "team" understand what to do in the event of an emergency, then you have a much better chance of surviving an incident like I encountered. Jakub's BOV is an fantastic evolution of a very good concept - giving a diver an easy way to switch from CC to OC with the flick of a lever, without having to abandon his DSV and search for a 2nd stage. That is why, on every Hammerhead CCR we sell, his BOV is standard equipment. Take care, Kevin Juergensen Juergensen Marine, Inc.
(Offline)

24th November 2007, 14:25	#10 (permalink)
wedivebc FIGJAM 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: 1,337	Re: CCR Cave Summit - NACD Quote: (Originally Posted by mattmexico) . If you just think about o/c bailout and can not even put your finger on what or why, that very thought of just thinking about bailout is the very reason to bail out, now, do not hesitate a split second and go to o/c bailout, because that might have been your last chance to do so ... BOV or not ... There is a definate pearl of wisdom! __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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