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[LiteHedded]

I had a brand new stage regulator be fine for 4 dives as an O2 bottle at 20 feet and then fail so that it delivered water on the 5th dive when I swapped it onto stage bottle and took it down to 50 feet. If that had been my backup regulator, it would have passed gear checks fine at the surface, or even shallow skills+drills, but would have given a nasty surprise at depth if I needed to donate gas.

a surprise that's easy enough to handle though...
on a dive where this really mattered you'd be on redundant tanks and first stages.
again, this happening after your buddy has already had his tank explode/run out of air/whatever is going to be exceedingly rare. it's just not your day. time to buddy breathe, use the inflator or just swim up.

 

[DCBC]

a surprise that's easy enough to handle though...
on a dive where this really mattered you'd be on redundant tanks and first stages.
again, this happening after your buddy has already had his tank explode/run out of air/whatever is going to be exceedingly rare. it's just not your day. time to buddy breathe, use the inflator or just swim up.

A few points:

1. I don't think that you can expect everyone to have redundant tanks and first stages on every dive they make.
2. In the future, you will not be able to expect that your buddy will be able to buddy breathe, as this skill will not be taught to the majority of new divers.
3. Just swimming up, may prove to be more difficult than you assume.
4. OOA is not an "exceedingly rare" occurrence, especially with divers who are not experienced in going deep. Divers in-general don't have a good handle on their gas consumption at depth.

 

[LiteHedded]

A few points:

1. I don't think that you can expect everyone to have redundant tanks and first stages on every dive they make.
2. In the future, you will not be able to expect that your buddy will be able to buddy breathe, as this skill will not be taught to the majority of new divers.
3. Just swimming up, may prove to be more difficult than you assume.
4. OOA is not an "exceedingly rare" occurrence, especially with divers who are not experienced in going deep. Divers in-general don't have a good handle on their gas consumption at depth.

1. I didn't say that
2. maybe not YOUR buddy. but mine will be able to do that
3. so now we've got TWO catastrophic failures AND you can't surface. use the inflator to breathe and curl up into the fetal position when you get home. this is not your day! lol
4. agreed. but two at the same time is. on a 'deep' dive you need to pay more attention when you're selecting a buddy anyway

 

[DCBC]

1. I didn't say that
2. maybe not YOUR buddy. but mine will be able to do that
3. so now we've got TWO catastrophic failures AND you can't surface. use the inflator to breathe and curl up into the fetal position when you get home. this is not your day! lol
4. agreed. but two at the same time is. on a 'deep' dive you need to pay more attention when you're selecting a buddy anyway

Yes, we have to choose our buddy carefully. Yes, we have to pay even more attention on a deep dive. However, not every diver is meticulous when it comes to buddy selection. Some people dive with an instant buddy and some of these don't go over buddy breathing at the beginning of the dive. Some don't know how; others don't care. Some don't do an extensive predive inspection and many of them were never taught how.

I agree that two catastrophic failures on one dive is uncommon. I have however experienced multiple failures on a few occasions. This why many systems in commercial diving require triple redundancy to be available to the diver. Overkill? They made it law because divers were dieing because they had only two. Think about that for a moment...

It is possible to occur. Personally that's how I train divers; to expect the improbable. You don't have to be the brightest bulb in the box to know if the improbable does happen, you can quickly be in a world of hurt.

The attitude of no problem I can just do this. If it has a malfunction, I'll just do this and if this happens I'll.... It doesn't work that way! The only thing you can expect, is that what you expect will seldom happen.

 

[LiteHedded]

Yes, we have to choose our buddy carefully. Yes, we have to pay even more attention on a deep dive. However, not every diver is meticulous when it comes to buddy selection. Some people dive with an instant buddy and some of these don't go over buddy breathing at the beginning of the dive. Some don't know how; others don't care. Some don't do an extensive predive inspection and many of them were never taught how.

I agree that two catastrophic failures on one dive is uncommon. I have however experienced multiple failures on a few occasions. This why many systems in commercial diving require triple redundant systems to be available to the diver. Overkill? They made it law because divers were dieing because they had only two. Think about that for a moment...

It is possible to occur. Personally that's how I train divers; to expect the improbable. You don't have to be the brightest bulb in the box to know if the improbable does happens, you can quickly be in a world of hurt.

The attitude of no problem I can just do this. If it has a malfunction, I'll just do this and if this happens I'll.... It doesn't work that way! The only thing you can expect is that what you expect will seldom happen.

this being the 'advanced' forum I suppose I'm assuming a certain level of competence. maybe that's where I've gone wrong.

still, despite the nightmare scenario you're describing it's still workable. both divers survive this dive. at a certain point we have to ask ourselves 'how many failures are we planning for?', pick a number, and live with it.
what if every regulator in the water fails and you're both entangled? it starts to get silly.
of course I'm not sure any of this is relevant to the original post but it's been fun.

 

[paddler3d]

These are maintenance and pre-dive check issues. You could also test your octopus when you are familiarizing your buddy with your alternate air setup. The, necklace second stages don't fail argument, I think dodges the question

You should test your octo as part of the pre-dive. I agree.

I've also see octos being dragged through the mud. I've haven't seen too many necklaced seconds in the mud, close, but not in.

I'm just saying that a typical octo is more likely to have issues vs. a necklaced second.

Also, people tend to buy octos of inferior quality and performance compared to their primary, where as folks who dive a necklaced second tend to dive the same second as their primary, resulting, typically in a good quality second.

I don't think it dodges the question.

 

[MXGratefulDiver]

Thanks for your response Gerbs. I do however have to disagree with your noted statement. You are not "in the same situation you would be in before, had you given a non-functioning secondary." Lets examine the difference:

#1 In my scenario

1. You (the Rescuer) has air and does not need to get to the surface.
2. The OOA Diver finds a non-functioning Secondary.
3. The OOA Diver will either ask to buddy breath, or do a CESA.
4. The OOA Diver is unencumbered; he simply drops the non-functioning secondary and does a CESA.
5. You would follow the OOA Diver to the surface and be there for support, as required.

#2 In your scenario

1. The OOA Diver has air and does not need to get to the surface.
2. You (the Rescuer) finds a non-functioning Secondary.
3. You will either ask to buddy breath, or do a CESA.
4. If a CESA is required, you are encumbered.
5. Trying to retrieve the only functioning regulator may result in both divers drowning.
6. Alternatively, you could attempt to remove your kit and make a CESA yourself.
7. The OOA Diver may not be able to closely follow you to the surface (suited with a non-functioning BC and an operational one in his hands).

Personally, I'm going to pick Door #1.

Neither of these are realistic assumptions, but rather classroom exercises intended to rationalize a particular way of doing things.

In the first scenario, if the OOA diver finds a non-functioning secondary their most likely response is going to be to take the one you are breathing from. You are now in a position to have to "fight off" a diver who is either near or already in full-blown panic. Dunno if you've ever dealt with a person who's actually panicked, but even that little 90-lb girl will come at you with the strength of a 600-lb gorilla when her survival instinct kicks in. Their only other option is, as you say, CESA. However, by now they have been out of air for several seconds, most likely having exerted themselves getting to you and dealing with stress rising to panic. That diver, even if they bolt, is extremely unlikely to remember ... or even have the option of remembering ... what the C in CESA stands for. It's a full-on bolt ... most likely while holding in whatever breath they last took ... again, survival instinct hard-wires us to do so ... and given the likelyhood that this isn't a very well-trained diver, they are unlikely to remember the first rule of diving in such a circumstance. By the time you arrive at the surface, your "help" will be unnecessary, as they will have embolized and will already be dead.

In the second scenario, you will have donated your primary after having very recently breathed off of it ... under even the most surprising and extreme circumstance you will have a "reserve" of several seconds to obtain another workable breathing source. If you have followed standard procedure you will have tested both of your regulators prior to beginning the dive, and since a necklaced regulator doesn't sit in a holder or drag along behind or below you, the chances for malfunction are extremely slim. And even if it does ... and even in the worst-case you listed above ... YOU are in a far more better position, having had a breath much more recently than the diver in Scenario #1, to initiate a CESA that will get you to safety without the risk of panic.

Bottom line is that the real enemy here is panic ... and the scenario that best reduces the risk of EITHER diver going into panic is the one that has the best chance for a happy ending ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Seems to me that a simple purge air test to the octo above
water before the dive is always a good idea. I personally always
swith to my octo for 6 to 8 breaths on decent and again on
hang time on the accent. My primary reason is to make sure
its working properly,for MY use if needed. I agree with others
that think donating your primary is a careless idea. While buddy
breathing should take place in an emergeny situation for the
"other ooa diver" if that diver is in total panic and i have a
not likely octo failure...cold as it sounds...he;s on his own. It
would be stupidy to risk my saftey.

This is good practice. In the real world ... at least the one I experience almost daily for the past nine years ... the long-hose user is far more likely to be breathing off their backup regulator prior to every dive than the short-hose user.

Why? Well, because it's right there under their mouth. The standard octopus is either attached by a clip ... most of which are a pain to re-stow once deployed, or it's dangling alongside the diver.

Furthermore, part of the mentality that goes along with the long hose is that the backup is for YOU ... and most people are far more motivated to use safety procedures intended for their own safety than they are for someone else's.

In effect, the biggest difference is that in the short-hose setup, the octopus is viewed as a backup for another diver ... almost an afterthought "just in case". In the long-hose setup, the necklace is viewed as a backup for the person who's wearing it, and is an integral part of that diver's safety equipment. Standard pre-dive checks include testing it on every dive.

In either case, breathing the backup on the surface doesn't really tell you much ... you need to take those breaths at a minimum with your head in the water to assure that the reg isn't leaking (i.e., diaphragm leaks or a malfunctioning mouthpiece ... which are the most common reg failures).

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Well no, lots of people are not comfortable with certain skills in the beginning, no need to be so harsh towards them. They should get more instruction or training in controlled conditions so they are more comfortable and can handle being regless for a few seconds. If I had given up diving when I couldn't handle my mask being off, I would have missed out on nearly two years of some of the most amazing experiences of my life.

Even PADI trains entry-level divers to be comfortable without a reg in their mouth for a few seconds ... assuming the class is taught as intended. Why else do you believe they require those silly reg-recovery exercises? I mean ... where is your reg while you're kneeling there in front of an instructor blowing bubbles?

... Bob (Grateful Diver)

 

[captain]

a complete loss of backgas by your 'buddy' AND your backup reg failing closed on the same dive?
ridiculously unlikely but not a huge deal. buddy breathe and surface.

Point is if you are saying something CAN happen even though it is unlikely what you are really saying is either it has happened or it will happen.