Not even a newbie yet!

[TobyFish]

Hi

I'm a PADI divemaster. I have been impressed by the simplicity of the DIR rig and the emphasis on streamlining, trim, and consistency among divers. However, because Diving systems are life-support systems I am not taking the idea of changing over lightly.

Having read the basics of the system I have two questions about the regulator configuration.

First... The long hose. It seems like a great idea, but I am concerned about the routing of the hose around the neck. I can imagine an out-of-air diver arriving unannounced, grabbing my primary and pulling it down and to my left. I would now have a tight loop of hose around my neck and a panicking diver in very close proximity. it's even possible that my primary, thus pulled down, will obstruct access to my secondary. Obviously as I don't have a DIR rig as yet, I cannot test this. Can any of you guys try it out and tell me if it's possible to end up garotted if the primary is pulled in the wrong direction? Or does it just slip off over the head, whichever way it is pulled

Second... The short hose. I like the idea of having it right under my chin, but what if my buddy needs air, and my primary reg fails. He and I can no longer share, there is no way we can buddy breathe from such a short hose. My current buddy and I can just about do it off a PADI-style mid-length primary hose, but even that is a struggle. Would two long hoses be feasible?

I hope these don't sound like heretic criticism, but I do need to evaluate DIR critically.

[Chris Fenton]

I am a PADI Instructor but only a Fundamentals level diver so I am by no means an expert.

As far as the first senario goes, I suppose it is possible. What I would do in this case is deploy the long hose (ie. release the excess from under my can light) and then with the new found slack pull the long house from the back of my neck over my head.

As far as the second senario goes; the odds of having another diver run out of gas at the same time that my primary failed are pretty small. If it did occur I would pull my necklace off and try to buddy breath as best as I could.

I really don't think two long hoses is a good idea.

I'm sure you will soon get more qualified answers.

Chris

[LCF]

If I duck my head, my long hose will slip over it no matter what direction it's pulled. (It might pull my mask strap off in the process )

No configuration is going to be absolutely perfect in every combination of failures. It's conceivable that your buddy could go OOA (although if he's DIR, it should be vanishingly unlikely) at the same moment that your primary reg suddenly and completely fails. At that point, you buddy breathe off the short hose, which would be difficult and stressful, or better, you have a third team member, and your buddy heads there for his air supply.

[TobyFish]

Thanks Guys, it's good to find an active forum where answers come quickly but are considered

I would like to answer a couple of points.

Firstly, DIR is clearly a strong system. It seems that it is _so_ strong because it considers and addresses unlikely failures as well as likely ones. So just because a problem is unlikely doesn't mean we shouldn't think of ways to mitigate it - providing they don't add more complexity and danger than it solves. I do of course _want_ the use the DIR system without further modification because otherwise it loses it's advantage of consistency.

If the risk of an out of air buddy is really "

Quote:

anishingly small

then why don't we dive on two short hoses? I am not unduly worried about the statistical chances of my reg failing exactly as I hand it off - I am more worried about the chances of a panicked diver in cold water enducing a free-flow either while breathing hard or over-purging my primary

I am encouraged that the hose slips off so easily - of course I will have to try this myself to be sure.

The suggesyion of getting more slack by unhooking the hose makes a lot of sense. I will still need to do some tests. My martial arts experience tells me that you will have a very short time to accomplish this maneuvre (in fact if the hose presses on your carotid sinus you may have no time at all - but hey... sometimes your number is just up - and at least you'll avoid all the unplasant panic). I would also think you would need to grasp the hose near your neck at the same time though, otherwise your panicking sea-anchor of a buddy will just pull all the new slack round your neck before you can use it.

As you say, no config is going to solve all possible problems, and if I only ever find two scary problems with DIR it will still beat most of the other configs I have seen.

thanks again

[ppo2_diver]

Quote: (Originally Posted by TobyFish)

If the risk of an out of air buddy is really "then why don't we dive on two short hoses?"

What about a catastrophic failure? For example, if you (and your buddy) are diving a single tank setup, and a tank o-ring blows? Someone's out of gas very fast. If the buddy has a long hose, it is easier to share air to the surface than it would be on a short hose.

[TobinGeorge]

Quote: (Originally Posted by TobyFish)

"then why don't we dive on two short hoses?

As with all config choices one needs to ask "What problems does this solve, vs what problems does potentially cause?"

Look at the problems that can be solved with the Long Hose primary with bungeed backup. The list is long, and well proven and documented in real diving emergencies.

What are the problems caused by the long hose? Is there a single documented case of a long hose induced problem when used by trained divers?

Now do the same analysis on your "two short hose" config.

I don't mean to seem dogmatic, but if you rigourously apply this method I'll bet you find yourself back at the rig your fundies instructor describes on day one of class.

Regards,


Tobin

[Devon Rob]

Hi Toby,
I admire your carefull attitude, especially as you voice concerns not only for yourself but also other divers.
I hope I am right in assuming that you are considering what could happen if you were to adopt a DIR rig within your current Divemaster duties without having suitable training yourself or trained buddies. You must realise that this does take away a lot of the important safety aspects that diving DIR as a complete system brings.
I have a lot of experience with first time and inexperienced divers and know that if you have a panicky diver (a panicking diver is usually only interested in ascent) then the benefit of a long hose is lost..you´re not going to get much distance between you. You wont be garroted or strangled but the extra length in this case is only of use if your buddy is prepared to use it.
As a DM you should have no concerns with decompression or exiting an overhead environment.
As to buddy breathing, you´re quite right, it can´t be done from a necklace. It´s only possible on a normal length hose for any length of time between two divers who remain calm (just remember back to your own stress test) and therefor not the first option with inexperienced divers. You still have all the other normal options including breathing from a freeflowing regulator, switching to a backup or taking your buddy´s second regulator. In a no-stop dive that should be plenty of options.

I guess my main point is not to confuse DIR with just diving a long hose.

All the best
Devon Rob

[TobyFish]

Sorry guys, I didn't want to spark a whole debate about the obvious lunacy of diving on two short hoses. It was an ironic comment. I was responding to the assertion that a second long (or standard length) hose was not worth considering because the chances of needing it were small. The same post suggested that the chances of running out of air were vanishingly small when diving DIR. Applying the same logic would lead to deciding that there was no need to rig for a potential OOA. This was "argument by ridiculous example" rather than a serious suggestion of an alternative config

[TobyFish]

Thanks Rob, your comments are very helpful. My divemaster duties are at present confined to being a certified assistant on PADI training courses. I agree with your sentiments and would add that if "Thou shalt not dive with non DIR buddies" is the number one rule then "thou shalt not dive with non DIR students while attempring to dive DIR yourself" would be a pretty close second.

Diving with open water students who are only just familiar with the yellow reg in the magic triangle and asking them to understand and utilise the long hose is asking for trouble and is moreover not DIR. As you say - doing this without DIR training myself would be both negligent and suicidal. In this situation I prefer a standard PADI-style rig, but ensuring that my octo is rigged so I can breathe it myself if my primary gets "donated".

Of course with novice students - the need for a donated reg is rarely due to true OOA, but more often due to a dropped reg during a skill, or a panic for some other reason, or just a complete gear rejection before bolting. In these cases - as a DM - I am usually watching the student and I more often than not see the situation developing - or I am sufficently detached (not being their buddy) to not be the one who gets clawed for a reg, so I can get to the diver before the problem gets going, with my octo deployed purged and pressed against their lips.

DIR is something I am considering for my own diving away from students - although I am somewhat wary of DIR-ing part time - hardly ideal!?

[JohnKendall]

Quote: (Originally Posted by TobyFish)

I was responding to the assertion that a second long (or standard length) hose was not worth considering because the chances of needing it were small. The same post suggested that the chances of running out of air were vanishingly small when diving DIR.

The post suggested that the chances of a buddy going OOA as well as your primary suddenly failing at the same time where very small.

You can always come up with scenarios that will mean that you don't have enough resources to survive, however the likelyhood of them occuring is so very small it's not really worth worrying about.

HTH
J