BOV: From design to implementation

Gilles · 22nd April 2007, 05:22

Quote: (Originally Posted by Dave Sutton)

Why not? Gas is gas..... bailout is done for flooded loops... and that does not affect the gas, no matter where carried. The fact of the matter is that much of the "sport diving" done with Rebreather's can be bailed out of using inboard gas only *IF it's all accessable for OC*.

Using a CEJN quick connect hose to the 02 supply, allowing it to be plugged into an OC reg of some sort when needed really expands the matrix of possibilities. Combine that with some *sensible* diluent and you can do a lot with the internal supplies of most rigs. Not "everything", but a lot.

All of my gas is part of my bail plan. I plan to be able to bail out SCC using *any one* of my gas supplies (internal diluent only when diving single dil, *either* of the two diluents only when carrying mix, or using 02 only) and OC using *"one out of two" or "two out of three"* of my gas supplies (either one or two diluents plus 02). Using diluents with enough 02 is the key here... diving deep my "utility gas" (meaning onboard diluent) goes to 50/50 nitrox, while the offboard trimix stays normoxic as long as possible.

02 = life. Carry it mixed, carry it pure, but carry it and be able to ACCESS IT.

Dave

I hope I can debate with you a little.

If your loop is flooded beyond recovery, then SCR is no longer an option and you're dependant on all your OC. This is the only scenario I can think of (so far) where OC access to your O2 would be useful.

In the case of the Meg, the only scenario where access to the O2 is lost is if the inhale side of the loop is lost. Open loop access of O2 remains (by using your inhale man-ad button) even if you sever the exhale side of the loop.

Hence, maybe the probabilities of needing OC accces to O2 are getting a little low in my particular case. Creating that access may introduce more hazard than useful options gained.

I stand to be corrected.

divetheworld · 22nd April 2007, 09:55

Quote: (Originally Posted by Dave Sutton)

Why not? Gas is gas..... bailout is done for flooded loops... and that does not affect the gas, no matter where carried. The fact of the matter is that much of the "sport diving" done with Rebreather's can be bailed out of using inboard gas only *IF it's all accessable for OC*.

Using a CEJN quick connect hose to the 02 supply, allowing it to be plugged into an OC reg of some sort when needed really expands the matrix of possibilities. Combine that with some *sensible* diluent and you can do a lot with the internal supplies of most rigs. Not "everything", but a lot.

All of my gas is part of my bail plan. I plan to be able to bail out SCC using *any one* of my gas supplies (internal diluent only when diving single dil, *either* of the two diluents only when carrying mix, or using 02 only) and OC using *"one out of two" or "two out of three"* of my gas supplies (either one or two diluents plus 02). Using diluents with enough 02 is the key here... diving deep my "utility gas" (meaning onboard diluent) goes to 50/50 nitrox, while the offboard trimix stays normoxic as long as possible.

02 = life. Carry it mixed, carry it pure, but carry it and be able to ACCESS IT.

Dave

I used to be a firm believer in using my inboard as a bail gas. It made my rig more manageable for a lot of dives. As my diving evolved, so did my bail strategy. As failures were experienced, so my plans became more solid.
Bailout is done for broken up rebreathers, regardless of cause. You carry bailout to compensate for the fact that the rebreather can go tits up.
I understand what you are saying, if its flooded then you can still stay on loop and use any of your O2 rich gases as source gas. Honourably so and I agree. If you bail to OC then the loop MUST be unserviceable or you would stay on loop, again I agree whole heartedly.
The question is, how many failures do you consider in your bail plan?

Personally, when I am on my way back from deep stuff in UK waters, I like to have very little in the bag labelled 'nasty surprises'.
Logically speaking, here is the way I see it. Planning an OC bail plan from a reasonably deep one, plan using O2 at 6m and plan using your stages for bail. Now take away the O2 assuming its lost. Chances are your looking at a bad bend.
Now plan without the O2. Assuming a failure not relating to O2 loss, you now have access to it at 6m and you get out substantially quicker or with more safety margin. But you get out safe.
I will plan with the mandate that a failure or total loss of any one gas supply will not result in a casualty. Whether that is solo or team based gas plans.
I have access to my o2 inboard via a switch block but I dont count on it.
Simply personal choices based upon risk assessment.
Essentially i see our bail strategies being almost identical with the exception that you expect to have access to pure O2 and I dont. I see the sound logic in your post, I just go one step further because dont feel comfortable with it.

Anyway, you asked a very good question "why not", I hope my logic gets through the rambling.

Brent

**Dave Sutton** · 22nd April 2007, 10:48

Quote: (Originally Posted by Gilles)

I hope I can debate with you a little.

If your loop is flooded beyond recovery, then SCR is no longer an option and you're dependant on all your OC. This is the only scenario I can think of (so far) where OC access to your O2 would be useful. .

Uhhh.............

(1): SCC is used either for *lost electronics* or *loss of your 02*.

(2): OC is used for a *lost loop*....that's the only situation in which *OC Bailout* is needed.

"Lost Loop" (IE flood) is the "Bang" situation around which bailout is planned. There is no reason to suspect that it will be combined with loss of gas, so why not use all gas, within reason, for OC "survival mode"? That means access to your 02 for deco, to a diluent that is breathable to the surface, and if deep, to some mix that will not nark you stupid while ascending. Seems to me that if I have access to my 02, my "utility gas" (air or nitrox, depending), and to my offboard bottom dil (when using trimix) that I already have all the gas I need.

Avoidance of huge dedicated OC gas supplies is my goal, sharing resoources allows this.

Typical configurations for my Mark-15:

Shallow no-deco or minimal-deco diving: Internal sphere of 02, internal sphere of air (or nitrox). Use of the combination to the BOV gives me "adequate" (but not excess) gas for OC "survival". This is what I would use in 100-130 feet of water "sport diving". Note: NO dedicated bailout gas. Why bother?

"Deeper" dive (to, say.... 220 feet): Internal sphere of 02. Internal sphere of 50/50 nitrox (used as utility gas). External diluent trimix 20/32 or similar. Use of this combination gives reasonable capacity for OC bailout and deco. Size of the external diluent cylinder adjusted for condition/depths.

Deeper yet: The offboard is (A) increased in size and is (B) taken below normoxic mix.

Sharing resources is the key here. There is no sense in carrying, for example, mix internally for diluent, mix externally for bailout, suit inflation gas, and nitrox for OC deco when if you simply rearrange the sort, you have what is needed without the need to carry duplicates.

Actual mileage may vary...

Off to test the rEvo. Have a great Sunday!

Dave

**Dave Sutton** · 22nd April 2007, 10:54

Quote: (Originally Posted by divetheworld)

Anyway, you asked a very good question "why not", I hope my logic gets through the rambling. Brent

Morning Brent,

I see all of your points, and respect your experience. My belief is that many divers experience is skewed by whatever failures they have experienced, so perhaps we are working from differeing world views. I've not *ever* had a loop flood, other than with crappy homebuilts I have made myself. So, in all the years I have been diving these things, I have *never* needed to bail out to OC. Why? (1): Top quality loop and (2): COMPLETE dedication of my maintenance time and resources to keeping it working. Cooper hoses, internal counterlungs, etc. Dunno what else to say, every diver has differing experiences.

Less is more. Meaning that less gear means you can dedicate more time to keeping it perfectly maintained, and less to go wrong to begin with.

To answer your failure matrix: I plan for loss of the loop OR of *one* (out of two or three) gas sources while being "comfortable but upset" and for loss of loop PLUS one gas source (out of two or three) while being "scared but alive". I do not plan to be able to "throw away all of the rig and all of the gas it carries".

Best,

Dave

Gilles · 22nd April 2007, 12:18

Quote: (Originally Posted by Dave Sutton)

Uhhh.............

I see that I have expressed myself poorly. For the sake of brevity, what I meant was exactly as you point out.

Where I'm struggling is the justification for building the option for OC inboard O2. The need arises only in the case of unrecoverable loop flood, and in my case, theoretically at least, loss of the inhale side of the loop (= about one half the probability of any kind of total of loop flood).

Quote: (Originally Posted by Dave Sutton)

Morning Brent,

I see all of your points, and respect your experience. My belief is that many divers experience is skewed by whatever failures they have experienced, so perhaps we are working from differeing world views. I've not *ever* had a loop flood, other than with crappy homebuilts I have made myself. So, in all the years I have been diving these things, I have *never* needed to bail out to OC. Why? (1): Top quality loop and (2): COMPLETE dedication of my maintenance time and resources to keeping it working. Cooper hoses, internal counterlungs, etc. Dunno what else to say, every diver has differing experiences.

Less is more. Meaning that less gear means you can dedicate more time to keeping it perfectly maintained, and less to go wrong to begin with.

To answer your failure matrix: I plan for loss of the loop OR of *one* (out of two or three) gas sources while being "comfortable but upset" and for loss of loop PLUS one gas source (out of two or three) while being "scared but alive". I do not plan to be able to "throw away all of the rig and all of the gas it carries".

Best,

Dave

Amen:

to the dedication toward loop integrity
minimization of the complexity and failure points of your system, and
appropriate mixing of bailout and
choice of utility gas.

The building of an OC option for inboard O2 would need to not create any hazard in itself, given the small probability it is ever needed in the first place.

Can't say I'm comfy with the switchblock idea (yet). Never even seen one (except in photo). Perhaps a method that uses another pair of QD's and a little extra hose, that avoids screw ups (such as the switch being in the wrong position)...

divetheworld · 22nd April 2007, 14:34

Quote: (Originally Posted by Dave Sutton)

Morning Brent,

I see all of your points, and respect your experience. My belief is that many divers experience is skewed by whatever failures they have experienced, so perhaps we are working from differeing world views. I've not *ever* had a loop flood, other than with crappy homebuilts I have made myself. So, in all the years I have been diving these things, I have *never* needed to bail out to OC. Why? (1): Top quality loop and (2): COMPLETE dedication of my maintenance time and resources to keeping it working. Cooper hoses, internal counterlungs, etc. Dunno what else to say, every diver has differing experiences.

Less is more. Meaning that less gear means you can dedicate more time to keeping it perfectly maintained, and less to go wrong to begin with.

To answer your failure matrix: I plan for loss of the loop OR of *one* (out of two or three) gas sources while being "comfortable but upset" and for loss of loop PLUS one gas source (out of two or three) while being "scared but alive". I do not plan to be able to "throw away all of the rig and all of the gas it carries".

Best,

Dave

Hi Dave,

Hope your enjoying playing with your new toyz.

You've had me talking with my colleagues today about this. I have to say that you have put me in two minds. Over the next couple of weeks I'm probably going to find myself talking myself in and out of it.

Is'nt it great having open minded discussions.

Brent.

Quote: (Originally Posted by Gilles)

Can't say I'm comfy with the switchblock idea (yet). Never even seen one (except in photo). Perhaps a method that uses another pair of QD's and a little extra hose, that avoids screw ups (such as the switch being in the wrong position)...

Yes, there is a lot of discipline required for the switch block. I check the position many times before jumping in. In fairness to its use, you dont ever switch it to O2 unless you are testing or in the shit.

brent

***schford*** · 22nd April 2007, 20:09

I believe that if you have a problem with your unit you should bail out to a completely independant bailout system be it OC or seperate Rebreather.

You should not count on being able to use any part of your Rebreather. The safest possible solution is to have completely independant bail out. Do not count on having access to any gas from your Rebreather be it Dil or O2.

My extensive research into Rebreather Fatalities for my minimising rebreather fatalities articles led me to this conclusion.

To put it simply if you have a problem with your unit bail out to an completely independant system - if you do not you are massivly increasing the likelyhood of becoming the next fatality, BSAC call it the incident pit - you need to get out of that Pit if something goes wrong with your rig.

Just because you have never had a loop or any type of failure is a stastical irrelevance as far as MR Murphey is concerned in terms of future failures.

Remember folks your onboard DIL and O2 is for your Rebreather only that is how it is designed and that is how it is taught - for a reason! - don't count on it for anything else.

To suggest that you should not carry completely independant bailout gas is foolhardy and totally irresponsable - please everyone make sure you carry bailout - there have been fatalities because people have not done this.

**Dave Sutton** · 22nd April 2007, 20:17

Quote: (Originally Posted by divetheworld)

Yes, there is a lot of discipline required for the switch block. I check the position many times before jumping in. In fairness to its use, you dont ever switch it to O2 unless you are testing or in the shit. brent

I actually only have the two diluents on the block, offboard thru a QD and inboard hard-hosed. The 02 whip would need to be manually connected as an "offboard gas" thru the offboard gas QD fitting on the shoulder block before it were available to either the ADV or the BOV. I would never have an 02 system available to OC without a manual plug-in needed to get it to the BOV.

The block is on my left shoulder, and position can be verified by toutch. Each gas has it's own on/off valve, so "no gas" can also be selected (IE disable the ADV for deco). Works great and is *not* subject to mis-selection.

Dave

**Dave Sutton** · 22nd April 2007, 20:21

Quote: (Originally Posted by schford)

I believe that if you have a problem with your unit you should bail out to a completely independant bailout system be it OC or seperate Rebreather. bailout - .

That's a fine *opinion*. But it's just one opinion. There is far more than one way to skin this cat. Give credit to the advanced methods that advanced users select. "Basic Methods" are just that: Dumbed down basic methods used to train large volumes of variable quality students in the most basic way to get along with a rebreather. It's not the end-all method. Do you carry three bailout gas systems (trimix, nitrox, and 02) all accessable open circuit? I do.... it's just that "some of it" happens to be hidden inside my rig, that's all.

Gas is Gas.... get OC access to it. More is better than less.

Best,

Dave

***schford*** · 22nd April 2007, 20:29

Quote: (Originally Posted by Dave Sutton)

That's a fine *opinion*. But it's just one opinion.

It is common sense and is the reason all the manufacturers and Agencies train people that way.

Like I said people have died not having independant bailout.

22nd April 2007, 05:22	#11 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 762	Re: BOV: From design to implementation Quote: (Originally Posted by Dave Sutton) Why not? Gas is gas..... bailout is done for flooded loops... and that does not affect the gas, no matter where carried. The fact of the matter is that much of the "sport diving" done with Rebreather's can be bailed out of using inboard gas only IF it's all accessable for OC. Using a CEJN quick connect hose to the 02 supply, allowing it to be plugged into an OC reg of some sort when needed really expands the matrix of possibilities. Combine that with some sensible diluent and you can do a lot with the internal supplies of most rigs. Not "everything", but a lot. All of my gas is part of my bail plan. I plan to be able to bail out SCC using any one of my gas supplies (internal diluent only when diving single dil, either of the two diluents only when carrying mix, or using 02 only) and OC using "one out of two" or "two out of three" of my gas supplies (either one or two diluents plus 02). Using diluents with enough 02 is the key here... diving deep my "utility gas" (meaning onboard diluent) goes to 50/50 nitrox, while the offboard trimix stays normoxic as long as possible. 02 = life. Carry it mixed, carry it pure, but carry it and be able to ACCESS IT. Dave I hope I can debate with you a little. If your loop is flooded beyond recovery, then SCR is no longer an option and you're dependant on all your OC. This is the only scenario I can think of (so far) where OC access to your O2 would be useful. In the case of the Meg, the only scenario where access to the O2 is lost is if the inhale side of the loop is lost. Open loop access of O2 remains (by using your inhale man-ad button) even if you sever the exhale side of the loop. Hence, maybe the probabilities of needing OC accces to O2 are getting a little low in my particular case. Creating that access may introduce more hazard than useful options gained. I stand to be corrected. __________________ Gilles http://www.dirrebreather.com
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22nd April 2007, 09:55	#12 (permalink)
divetheworld Dive porn pimp Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Classic Kiss Other CCR Join Date: Mar 2005 Location: Leeds, England Posts: 1,586	Re: BOV: From design to implementation Quote: (Originally Posted by Dave Sutton) Why not? Gas is gas..... bailout is done for flooded loops... and that does not affect the gas, no matter where carried. The fact of the matter is that much of the "sport diving" done with Rebreather's can be bailed out of using inboard gas only IF it's all accessable for OC. Using a CEJN quick connect hose to the 02 supply, allowing it to be plugged into an OC reg of some sort when needed really expands the matrix of possibilities. Combine that with some sensible diluent and you can do a lot with the internal supplies of most rigs. Not "everything", but a lot. All of my gas is part of my bail plan. I plan to be able to bail out SCC using any one of my gas supplies (internal diluent only when diving single dil, either of the two diluents only when carrying mix, or using 02 only) and OC using "one out of two" or "two out of three" of my gas supplies (either one or two diluents plus 02). Using diluents with enough 02 is the key here... diving deep my "utility gas" (meaning onboard diluent) goes to 50/50 nitrox, while the offboard trimix stays normoxic as long as possible. 02 = life. Carry it mixed, carry it pure, but carry it and be able to ACCESS IT. Dave I used to be a firm believer in using my inboard as a bail gas. It made my rig more manageable for a lot of dives. As my diving evolved, so did my bail strategy. As failures were experienced, so my plans became more solid. Bailout is done for broken up rebreathers, regardless of cause. You carry bailout to compensate for the fact that the rebreather can go tits up. I understand what you are saying, if its flooded then you can still stay on loop and use any of your O2 rich gases as source gas. Honourably so and I agree. If you bail to OC then the loop MUST be unserviceable or you would stay on loop, again I agree whole heartedly. The question is, how many failures do you consider in your bail plan? Personally, when I am on my way back from deep stuff in UK waters, I like to have very little in the bag labelled 'nasty surprises'. Logically speaking, here is the way I see it. Planning an OC bail plan from a reasonably deep one, plan using O2 at 6m and plan using your stages for bail. Now take away the O2 assuming its lost. Chances are your looking at a bad bend. Now plan without the O2. Assuming a failure not relating to O2 loss, you now have access to it at 6m and you get out substantially quicker or with more safety margin. But you get out safe. I will plan with the mandate that a failure or total loss of any one gas supply will not result in a casualty. Whether that is solo or team based gas plans. I have access to my o2 inboard via a switch block but I dont count on it. Simply personal choices based upon risk assessment. Essentially i see our bail strategies being almost identical with the exception that you expect to have access to pure O2 and I dont. I see the sound logic in your post, I just go one step further because dont feel comfortable with it. Anyway, you asked a very good question "why not", I hope my logic gets through the rambling. Brent __________________ Attitude and self praise is no reccomendation. Dont try to be a great man, just be a man and let history be the judge of you. CHECK OUT OUR INTERWEBS FOR CUSTOM REBREATHER UPGRADES *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe Last edited by divetheworld : 22nd April 2007 at 10:19.
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22nd April 2007, 10:48	#13 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,674	Re: BOV: From design to implementation Quote: (Originally Posted by Gilles) I hope I can debate with you a little. If your loop is flooded beyond recovery, then SCR is no longer an option and you're dependant on all your OC. This is the only scenario I can think of (so far) where OC access to your O2 would be useful. . Uhhh............. (1): SCC is used either for lost electronics or loss of your 02. (2): OC is used for a lost loop....that's the only situation in which OC Bailout is needed. "Lost Loop" (IE flood) is the "Bang" situation around which bailout is planned. There is no reason to suspect that it will be combined with loss of gas, so why not use all gas, within reason, for OC "survival mode"? That means access to your 02 for deco, to a diluent that is breathable to the surface, and if deep, to some mix that will not nark you stupid while ascending. Seems to me that if I have access to my 02, my "utility gas" (air or nitrox, depending), and to my offboard bottom dil (when using trimix) that I already have all the gas I need. Avoidance of huge dedicated OC gas supplies is my goal, sharing resoources allows this. Typical configurations for my Mark-15: Shallow no-deco or minimal-deco diving: Internal sphere of 02, internal sphere of air (or nitrox). Use of the combination to the BOV gives me "adequate" (but not excess) gas for OC "survival". This is what I would use in 100-130 feet of water "sport diving". Note: NO dedicated bailout gas. Why bother? "Deeper" dive (to, say.... 220 feet): Internal sphere of 02. Internal sphere of 50/50 nitrox (used as utility gas). External diluent trimix 20/32 or similar. Use of this combination gives reasonable capacity for OC bailout and deco. Size of the external diluent cylinder adjusted for condition/depths. Deeper yet: The offboard is (A) increased in size and is (B) taken below normoxic mix. Sharing resources is the key here. There is no sense in carrying, for example, mix internally for diluent, mix externally for bailout, suit inflation gas, and nitrox for OC deco when if you simply rearrange the sort, you have what is needed without the need to carry duplicates. Actual mileage may vary... Off to test the rEvo. Have a great Sunday! Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
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22nd April 2007, 10:54	#14 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,674	Re: BOV: From design to implementation Quote: (Originally Posted by divetheworld) Anyway, you asked a very good question "why not", I hope my logic gets through the rambling. Brent Morning Brent, I see all of your points, and respect your experience. My belief is that many divers experience is skewed by whatever failures they have experienced, so perhaps we are working from differeing world views. I've not ever had a loop flood, other than with crappy homebuilts I have made myself. So, in all the years I have been diving these things, I have never needed to bail out to OC. Why? (1): Top quality loop and (2): COMPLETE dedication of my maintenance time and resources to keeping it working. Cooper hoses, internal counterlungs, etc. Dunno what else to say, every diver has differing experiences. Less is more. Meaning that less gear means you can dedicate more time to keeping it perfectly maintained, and less to go wrong to begin with. To answer your failure matrix: I plan for loss of the loop OR of one (out of two or three) gas sources while being "comfortable but upset" and for loss of loop PLUS one gas source (out of two or three) while being "scared but alive". I do not plan to be able to "throw away all of the rig and all of the gas it carries". Best, Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 22nd April 2007 at 10:57.
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22nd April 2007, 12:18	#15 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 762	Re: BOV: From design to implementation Quote: (Originally Posted by Dave Sutton) Uhhh............. I see that I have expressed myself poorly. For the sake of brevity, what I meant was exactly as you point out. Where I'm struggling is the justification for building the option for OC inboard O2. The need arises only in the case of unrecoverable loop flood, and in my case, theoretically at least, loss of the inhale side of the loop (= about one half the probability of any kind of total of loop flood). Quote: (Originally Posted by Dave Sutton) Morning Brent, I see all of your points, and respect your experience. My belief is that many divers experience is skewed by whatever failures they have experienced, so perhaps we are working from differeing world views. I've not ever had a loop flood, other than with crappy homebuilts I have made myself. So, in all the years I have been diving these things, I have never needed to bail out to OC. Why? (1): Top quality loop and (2): COMPLETE dedication of my maintenance time and resources to keeping it working. Cooper hoses, internal counterlungs, etc. Dunno what else to say, every diver has differing experiences. Less is more. Meaning that less gear means you can dedicate more time to keeping it perfectly maintained, and less to go wrong to begin with. To answer your failure matrix: I plan for loss of the loop OR of one (out of two or three) gas sources while being "comfortable but upset" and for loss of loop PLUS one gas source (out of two or three) while being "scared but alive". I do not plan to be able to "throw away all of the rig and all of the gas it carries". Best, Dave Amen: to the dedication toward loop integrity minimization of the complexity and failure points of your system, and appropriate mixing of bailout and choice of utility gas. The building of an OC option for inboard O2 would need to not create any hazard in itself, given the small probability it is ever needed in the first place. Can't say I'm comfy with the switchblock idea (yet). Never even seen one (except in photo). Perhaps a method that uses another pair of QD's and a little extra hose, that avoids screw ups (such as the switch being in the wrong position)... __________________ Gilles http://www.dirrebreather.com Last edited by Gilles : 22nd April 2007 at 13:11.
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22nd April 2007, 14:34	#16 (permalink)
divetheworld Dive porn pimp Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Classic Kiss Other CCR Join Date: Mar 2005 Location: Leeds, England Posts: 1,586	Re: BOV: From design to implementation Quote: (Originally Posted by Dave Sutton) Morning Brent, I see all of your points, and respect your experience. My belief is that many divers experience is skewed by whatever failures they have experienced, so perhaps we are working from differeing world views. I've not ever had a loop flood, other than with crappy homebuilts I have made myself. So, in all the years I have been diving these things, I have never needed to bail out to OC. Why? (1): Top quality loop and (2): COMPLETE dedication of my maintenance time and resources to keeping it working. Cooper hoses, internal counterlungs, etc. Dunno what else to say, every diver has differing experiences. Less is more. Meaning that less gear means you can dedicate more time to keeping it perfectly maintained, and less to go wrong to begin with. To answer your failure matrix: I plan for loss of the loop OR of one (out of two or three) gas sources while being "comfortable but upset" and for loss of loop PLUS one gas source (out of two or three) while being "scared but alive". I do not plan to be able to "throw away all of the rig and all of the gas it carries". Best, Dave Hi Dave, Hope your enjoying playing with your new toyz. You've had me talking with my colleagues today about this. I have to say that you have put me in two minds. Over the next couple of weeks I'm probably going to find myself talking myself in and out of it. Is'nt it great having open minded discussions. Brent. Quote: (Originally Posted by Gilles) Can't say I'm comfy with the switchblock idea (yet). Never even seen one (except in photo). Perhaps a method that uses another pair of QD's and a little extra hose, that avoids screw ups (such as the switch being in the wrong position)... Yes, there is a lot of discipline required for the switch block. I check the position many times before jumping in. In fairness to its use, you dont ever switch it to O2 unless you are testing or in the shit. brent __________________ Attitude and self praise is no reccomendation. Dont try to be a great man, just be a man and let history be the judge of you. CHECK OUT OUR INTERWEBS FOR CUSTOM REBREATHER UPGRADES *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe
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22nd April 2007, 20:09	#17 (permalink)
*schford* Despotic Overlord Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: London, UK Posts: 3,562	Re: BOV: From design to implementation I believe that if you have a problem with your unit you should bail out to a completely independant bailout system be it OC or seperate Rebreather. You should not count on being able to use any part of your Rebreather. The safest possible solution is to have completely independant bail out. Do not count on having access to any gas from your Rebreather be it Dil or O2. My extensive research into Rebreather Fatalities for my minimising rebreather fatalities articles led me to this conclusion. To put it simply if you have a problem with your unit bail out to an completely independant system - if you do not you are massivly increasing the likelyhood of becoming the next fatality, BSAC call it the incident pit - you need to get out of that Pit if something goes wrong with your rig. Just because you have never had a loop or any type of failure is a stastical irrelevance as far as MR Murphey is concerned in terms of future failures. Remember folks your onboard DIL and O2 is for your Rebreather only that is how it is designed and that is how it is taught - for a reason! - don't count on it for anything else. To suggest that you should not carry completely independant bailout gas is foolhardy and totally irresponsable - please everyone make sure you carry bailout - there have been fatalities because people have not done this. __________________ Bailout and Kit Management account for Murphy's Law The only bad question is one you did not ask and later wish you had. Use of Rebreather World is subject to the Rebreather World Terms & Conditions of Use Last edited by schford : 22nd April 2007 at 20:14.
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22nd April 2007, 20:17	#18 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,674	Re: BOV: From design to implementation Quote: (Originally Posted by divetheworld) Yes, there is a lot of discipline required for the switch block. I check the position many times before jumping in. In fairness to its use, you dont ever switch it to O2 unless you are testing or in the shit. brent I actually only have the two diluents on the block, offboard thru a QD and inboard hard-hosed. The 02 whip would need to be manually connected as an "offboard gas" thru the offboard gas QD fitting on the shoulder block before it were available to either the ADV or the BOV. I would never have an 02 system available to OC without a manual plug-in needed to get it to the BOV. The block is on my left shoulder, and position can be verified by toutch. Each gas has it's own on/off valve, so "no gas" can also be selected (IE disable the ADV for deco). Works great and is not subject to mis-selection. Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 22nd April 2007 at 20:22.
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22nd April 2007, 20:21	#19 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,674	Re: BOV: From design to implementation Quote: (Originally Posted by schford) I believe that if you have a problem with your unit you should bail out to a completely independant bailout system be it OC or seperate Rebreather. bailout - . That's a fine opinion. But it's just one opinion. There is far more than one way to skin this cat. Give credit to the advanced methods that advanced users select. "Basic Methods" are just that: Dumbed down basic methods used to train large volumes of variable quality students in the most basic way to get along with a rebreather. It's not the end-all method. Do you carry three bailout gas systems (trimix, nitrox, and 02) all accessable open circuit? I do.... it's just that "some of it" happens to be hidden inside my rig, that's all. Gas is Gas.... get OC access to it. More is better than less. Best, Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 22nd April 2007 at 20:25.
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22nd April 2007, 20:29	#20 (permalink)
*schford* Despotic Overlord Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: London, UK Posts: 3,562	Re: BOV: From design to implementation Quote: (Originally Posted by Dave Sutton) That's a fine opinion. But it's just one opinion. It is common sense and is the reason all the manufacturers and Agencies train people that way. Like I said people have died not having independant bailout. __________________ Bailout and Kit Management account for Murphy's Law The only bad question is one you did not ask and later wish you had. Use of Rebreather World is subject to the Rebreather World Terms & Conditions of Use
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