Hose length for Rec only diver

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Roman mentioned Cozumel, so I thought I would bring up something I've been thinking about. I was going to start a separate thread, but what the heck. More than once we saw a DM hand a long hose to a diver who signaled "Low on Air" and then continued to lead the diver along with the rest of the group for a while as though nothing had happened. Does anyone feel that because the long hose makes this sort of thing easy that it invites "abuse" of the convenience?
 
I suspect it may introduce a complacency where it's so easy that it could feel normal. I wouldn't like to expand an OOA situation by making it uncomfortable but disregarding it as an event is worse in my opinion.
 
I feel even stronger against starting and doing a dive sharing air. Do what you wish, but in my mind doing that air shared dive was wrong and dangerous. Posting it on a public forum even more so. I hope a brand new diver doesn't attempt the same and find him/herself in trouble then putting two people in danger.
Now, while we are getting a bit off topic - hose lengths were the starting point - I have to comment on this. Doing it was simply not dangerous - at no time was anyone in an OOA situation (In contrast, I would agree, had he started the dive with no gas at all, that would have been a bit on the edge. But that wasn't the case.) Posting this experience is definitely not dangerous. If there is concern as to what a new diver might do as a result of reading something in a thread here, then we need, IMMEDIATELY, to close SB because there is simply too much information / misinformation being put up. In fact, we probably should take down the Internet altogether, or have government censors assigned to decide what is safe to post and what is not.
If two divers are sharing one tank for a dive, where is the back up?
Again, let''s make sure the statements are accurate and factual. One diver (the LOA diver) had a fully functional, working air supply, with 500 psi in an AL80, at all times. That was always a back-up for him, and for whomever he was sharing air with at a given time. If the donating diver had an equipment malfunction, for example, then the two of them still had the LOA diver's gas supply available to make a normal ascent. If that is considered a problem - e.g. a diver has an equipment malfunction at the end of a dive, and has to share his buddy's air to surface - then we should change the fact that we (often) dive only a single cylinder. If 2 divers cannot make a normal ascent from 50 feet, in benign conditions, sharing air from an AL80 with 500 psi at the start of the ascent, I would hazard the opinion that they should not be in the water - at all. But, in addition to that back-up, there were 6 divers in the water, with a combined air supply of 400 cf at the start of the dive, and 77.4 cf at the end of the dive.

Nonetheless, I do agree with your statement - 'do as you wish'. If someone else would not want to do such a dive, I wouldn't force them to do so, nor would I criticize them for being unwilling to do so. We had fun doing it - it tested our skills, it helped improve our precision of swimming while sharing air, it enhanced our comfort and confidence. And, it was a good dive, in terms of the quality of marine life we saw, etc.
flots am:
Because if a true OOA emergency pops up, you're now left to decide which diver to ignore.
NOT true, at all. Both divers (the LOA diver and the one he was sharing air with at any given moment) had air. If the donating diver at a particular point went OOA, the two of them still had the air in the LOA diver's cylinder (not to mention the other 4 divers in the immediate vicinity). Statements like this contribute to my concern about our sometimes un-thinking adherence to 'rules' or 'guidelines'. If you don't think 500psi in an AL80 (12cf) is an acceptable reserve - for a normal air-sharing ascent from 50 feet, to answer your previous question - then what would you consider acceptable? 1000 psi? When diving with a buddy, do you (both) therefore always surface with 1000psi? If so, good for you. I don't personally find that to be necessary, but 'do as you wish'. Seriously - can a competent, experienced diver execute a CESA from 50 ft? Probably. So, having 12 cf of air to share during a normal, controlled, 30 fpm ascent is easily an acceptable reserve - for ME, and for the others on that dive. But, as I have said several times, if that is not enough for YOU / another diver, that's certainly your decision and I won't fault it.

For me, this has been a very helpful discussion. I am now thinking that this activity can become a good training exercise, going forward - it combines elements of buddy team diving, gas management, buoyancy control, dive planning etc. So, I am thinking of getting a group of instructors together, and trying it at our local quarry - work out the logistics of offering it as a workshop next season to other divers in our Club. For example, 4 divers enter the water with full cylinders, and one diver is designated as the 'dependent' diver, and shares air for an entire 30 - 45 minute dive around a defined course, and returns with a full cylinder. That kind of practice builds confidence and enhances skills.
 
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I suspect it may introduce a complacency where it's so easy that it could feel normal. I wouldn't like to expand an OOA situation by making it uncomfortable but disregarding it as an event is worse in my opinion.

Right. I've been trained to do "minimum gas" or "rock bottom" calculations that tell me how much gas my buddy and I need to complete a safe ascent, but am I subject to complacency from having the convenience of not ascending immediately when one of us becomes LOA? The DMs in Cozumel may have an intuitive sense of these numbers, but less experienced divers probably do not. Maybe there is some training/education that needs to go hand in hand with the long hose configuration to deter complacency.
 
NOT true, at all. Both divers (the LOA diver and the one he was sharing air with at any given moment) had air. If the donating diver at a particular point went OOA, the two of them still had the air in the LOA diver's cylinder (not to mention the other 4 divers in the immediate vicinity). Statements like this contribute to my concern about our sometimes un-thinking adherence to 'rules' or 'guidelines'.

The reasoning behind rules is often only apparent in hindsight.

If you don't think 500psi in an AL80 (12cf) is an acceptable reserve - for a normal air-sharing ascent from 50 feet, to answer your previous question - then what would you consider acceptable? 1000 psi?

What I consider acceptable is not shaving the margins until you reach the point where you can't actually handle an emergency and if your SPG is off by a couple of hundred PSI, that you now have two OOA divers.

When diving with a buddy, do you (both) therefore always surface with 1000psi? If so, good for you. I don't personally find that to be necessary, but 'do as you wish'. Seriously - can a competent, experienced diver execute a CESA from 50 ft? Probably. So, having 12 cf of air to share during a normal, controlled, 30 fpm ascent is easily an acceptable reserve - for ME, and for the others on that dive. But, as I have said several times, if that is not enough for YOU / another diver, that's certainly your decision and I won't fault it.

My buddy and I maintain enough gas to get us both safely to the surface from any point in the dive. This means different things under different conditions and depths. I might easily arrive at the surface with 500PSI, but you can be sure I won't be wandering around underwater with it.

Seriously - can a competent, experienced diver execute a CESA from 50 ft? Probably. So, having 12 cf of air to share during a normal, controlled, 30 fpm ascent is easily an acceptable reserve - for ME, and for the others on that dive. But, as I have said several times, if that is not enough for YOU / another diver, that's certainly your decision and I won't fault it.

The "E" in CESA stands for "Emergency". It's not a dive plan, it's an admission that someone screwed up.

That kind of practice builds confidence and enhances skills.

I believe you're just reinvented 1960. These types of exercises were eliminated for various combinations of being dangerous or ineffective or because they were replaced with procedures or equipment that made them irrelevant or unnecessarily risky.

If you shave enough safety margins, eventually someone is going to get hurt.

flots.
 
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More than once we saw a DM hand a long hose to a diver who signaled "Low on Air" and then continued to lead the diver along with the rest of the group for a while as though nothing had happened. Does anyone feel that because the long hose makes this sort of thing easy that it invites "abuse" of the convenience?
Not at all. I don't think what the DM did is 'abuse' in any way. This is not dis-similar to the Bonaire experience that I brought up. As you describe it, the Cozumel diver was not OUT of air, merely letting the DM know that s/he was getting low on air - which could have meant they were down to 1000psi, for example. If the DM has a good / low RMV (as many Caribbean DMs seem to have) and plenty of gas, why not share air for a bit, to allow that LOA diver (and the rest of the group) to extend the dive? I have also seen this from time to time in the Caribbean.
 
Not at all. I don't think what the DM did is 'abuse' in any way. This is not dis-similar to the Bonaire experience that I brought up. As you describe it, the Cozumel diver was not OUT of air, merely letting the DM know that s/he was getting low on air - which could have meant they were down to 1000psi, for example. If the DM has a good / low RMV (as many Caribbean DMs seem to have) and plenty of gas, why not share air for a bit, to allow that LOA diver (and the rest of the group) to extend the dive? I have also seen this from time to time in the Caribbean.

And I tend to agree with you in the case of Cozumel DMs who probably have an intuitive sense of gas consumption along with that low low RMV. The more provocative question (see my follow-up post above) is whether divers with less experience/training might let themselves fall into a habit of sharing air with their long hose. Tying this in to the original topic of the thread, does the long hose need to come with some training about "minimum gas"/"rock bottom"? If every newly minted OW diver had a long hose at his disposal, would we see divers sharing air merely to extend a dive in situations in which calculations would have indicated that they keep that air in reserve for an emergency ascent?
 
The reasoning behind rules is often only apparent in hindsight.
The reasoning may also never be apparent because the reasons for starting the rule / practice to begin with have long since disappeared, but people continue to do things, without thinking about why.
What I consider acceptable is not shaving the margins until you reach the point where you can't actually handle an emergency and if your SPG is off by a couple of hundred PSI, that you now have two OOA divers.
Very reasonable. I would agree. But, what is the 'margin' that is actually being shaved? What is the substantive safety difference between two divers being at 50 ft at the end of a dive, with two cylinders showing 500 psi on the respective SPGs, and two divers starting a dive with one cylinder showing 500 psi and a second cylinder showing 3000psi, if the intent is not to use gas from the 500psi cylinder unless necessary? There is simply nothing wrong with planning an air share dive, if the sharing diver has a back-up sufficient to terminate the dive - at any time - and ascend safely without sharing. There is a big difference between a 'trust me' dive, and a planned, air-share dive. If the SPG(s) is / are off, then whether the 6th diver started with 500 or 3000 is completely irrelevant. Two divers could go still go OOA at the same time at the end of the dive, and the same situation would result. What one of them started with makes no difference whatsoever. Air you have already consumed is not a resource (any more than depth above you, or a full cylinder on shore).

Every time we submerge we assume some element of risk - of a catastrophic equipment failure, of a medical event, etc. The likelihood of two SPGs simultaneously and spontaneously failing (being off by several hundred psi), just at the time when two divers are at 500psi at 50ft, is quite remote, so remote that there is no standard for carrying two SPGs on every dive. Do you routinely carry two SPGs on every single cylinder, recreational dive? If not, why not? I don't, either, by the way. The likelihood is no greater than the probability of a meteor striking the water where we are diving. And, I usually don't include the possibility of a meteor strike in my dive planning.

I dive a regulator in OW classes with a SPG that is 300 psi off (shows 300psi when unpressurized). I have done that for years, and I keep the SPG because it helps me illustrate to students why we check the SPG before we initially pressurize a cylinder. I don't just verbalize the 'why', I show them the 'why'. Is that unsafe? Does it materially shave a safety margin? Not really.
My buddy and I maintain enough gas to get us both safely to the surface from any point in the dive. This means different things under different conditions.
Exactly! Thank you for agreeing with, and reinforcing, my point. The conditions and the situation have to be considered. How do YOU define 'safely', for example? For that matter, how do you know that your SPGs are not both 'off by a couple of hundred PSI'? And, by the way, that is exactly what we did on the dive in question - maintained enough gas to get ALL 6 of us safely to the surface from any point in the dive.
The "E" in CESA stands for "Emergency". It's not a dive plan, it's an admission that someone screwed up.
That is exactly right. It is an emergency procedure. It remains as a possible action in an emergency. There was no intent to use a CESA during our dive, unless there was an emergency - that was no different from any other dive. Just as with ANY dive, we knew that such a maneuver could be attempted, if necessary. On every dive, I think about whether a CESA would be even feasible, under the particular conditions applicable at that point, and plan accordingly. I used it as an example of contingencies that are available, not as a statement of what was in a plan.
I believe you're just reinvented 1960. These types of exercises were eliminated for various combinations of being dangerous or ineffective or because they were replaced with procedures or equipment that made them irrelevant or unnecessarily risky.
Interesting thought but it is not really a reinvention. Yes, some REQUIRED procedures have been eliminated, by some agencies - the 'doff and don' as one example, or buddy breathing as another. Yet, we still have DM candidates practice buddy breathing. Why? Because the skill may be useful, because mainly it helps future dive professionals build confidence. (How about requiring certain divers in training - DM candidates - exchange gear - mask, fins, BCD - underwater, while buddy breathing? Is that too dangerous?) Quite a few people still do 'doff and dons' for fun, for the same reason - it builds confidence, enhances skill, etc. We are also talking about an activity that is not required for anyone. Individuals make their own decision whether to participate in a planned air-share dive, on the basis of their skills and experience.

In aviation, we have spot-landing contests from time to time. Why? Because they give pilots a chance to improve skills, to enhance the precision of their approach / landing, because they build confidence. Now, if you want to say that such practices are dangerous, then we need to change the entire structure of pilot training, because a short field landing poses the same challenges, and that is a required procedure to initially obtain a license.

How did rodeos start? Cowboys began to informally 'compete' on the basis of skills they used in their daily work, to see just good they were, how good they could become (and to see if they were 'better' than their compatriots). Perhaps, if we did more of that in recreational diving, we would have better recreational divers.

It is funny - we include air-sharing skill development in OW training. And, then we lament the fact that too few divers actually practice the skills - ever - after certification. Effectively practicing the skills is not simply a matter of signaling out of air, sharing a second stage for 15 seconds while planted on a platform, and then cutting the exercise. Even in primary training, the skill involves swimming for at least one minute while sharing air. Why not extend that, because in a real emergency the chances are that it will be required?

Spot landing contests may not necessarily be suitable for (some / many) novice pilots. Rodeos may not necessarily be suitable for (some / many) novice riders. And, planned, extended air share dives may not necessarily be suitable for (some / many) novice divers, But, to arbitrarily say that spot-landing contests, rodeos, or planned air share dives are categorically dangerous, or unsafe, or that they cut necessarily safety margins to the extent emergencies can no longer be handled, is simply illogical, and frankly absurd.
If you shave enough safety margins, eventually someone is going to get hurt.
Again, what is the safety margin that is actually being materially shaved? A diver starts a dive with 500 psi in an AL 80 - no less gas than he would have when he begins his ascent at the end of a dive. At the first point where sharing air is not an option, he still has the option of doing exactly what he would normally do - end the dive and ascend normally. Would it be shaving a margin to have six divers start a dive with AL63s instead of AL80s? One answer would be - it depends on the dive', and I would agree. But, if the answer is, 'Yes. It would shave the margin', should we then start all dives with only HP100s or larger cylinders? The primary difference in this case was that an experienced, capable diver intentionally started a shore dive - in benign conditions where simply ascending to the surface was a continuing option - with less than a full cylinder, after discussing it with 5 team mates, and making a specific plan. No margins were materially shaved.

I am not so much arguing, as illustrating that even in your response you - appropriately - point out that conditions vary, and judgments are made on the basis of those varying conditions. And the thinking that this is materially shaving some safety margin is simply not cognitively sound. It is different, not unsafe.
 
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Because if a true OOA emergency pops up, you're now left to decide which diver to ignore.
All time when two divers have two independent air sources with about 900-1000psi (in AL80 equivalent) in each with two second stages on each, I think this dive is safety enough.
Colliam7 mentioned similar.
Order how they used the air it is only training issue.
And long hose helps here to allow to see corals and fishes and not only each other. :)
 
The more provocative question (see my follow-up post above) is whether divers with less experience/training might let themselves fall into a habit of sharing air with their long hose. . . does the long hose need to come with some training about "minimum gas"/"rock bottom"? If every newly minted OW diver had a long hose at his disposal, would we see divers sharing air merely to extend a dive in situations in which calculations would have indicated that they keep that air in reserve for an emergency ascent?
Now, those are interesting questions and I have to say i have never considered such a possibility. :) On one hand, I think it would be absolutely phenomenal if the majority of divers could get to the point where they felt so comfortable sharing air - with a 7' hose or with a 40" hose - that this could become a legitimate possibility. That would be great (the level of comfort, not the complacency). On the other, I don't really believe - but I could be wrong - that it (complacency leading to OOA situations) is a necessarily likely or predictable outcome of simply using a long hose. But, now that you have brought it up, I will have to think on that one. Thanks.
 

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