Double Tank Manifolds, Bad Idea!

[DevonDiver]

I agree with Dale. There is a distinction between recreational (inc solo) and technical/overhead diving. This impacts upon the protocols needed to deal with issues.

If access to the surface is an option, then it should remain the primary option and first solution. That said, an ability to deal with issues without the assumption of immediately surfacing remains a critical element for dive safety; especially so for solo divers. There are potential factors which could result in a recreational diver being detained at depth.

Skills like 'valve feathering', or even 'manifold shut-down' are just tools in the toolbox. For some dives/configurations, those tools are critical. For others, not so - but they still remain in the inventory should they prove necessary.

Emergencies should be handled in a manner that ensures the most timely cessation of risks to the diver. For that reason, the protocols should be as simplified as possible and the need for problem solving, experimentation and 'free-styling' should be kept to an absolute minimum.

Access to the surface is, IMHO, the primary factor to be considered. In that respect, the old adage applies: Gas is time, time is life.

If you have enough gas to get the surface and attain positive buoyancy then you live. If not, then you die. This is the fundamental calculation.

Providing the diver has taken steps (through equipment, training and planning) to ensure a positive result from that calculation, given all feasible and reasonable contingencies, then they have succeeded in their risk mitigation. All else is dogma...

 

[Doppler]

So Doppler says it doesn't significantly impact (significantly) on a platform (pretty pool like) and then Peter gives some info about a real life situation. Steve, drills and sterile environments aren't what I'm talking about. I'm talking about real deal stuff.

Peter, I'd love to hear more details, really. That's the kind of stuff I'm interested in. You said deco reg, shallow, deep, how much reserve, nature of failure, etc etc. All important details.

Not to be a pedantic, hard-nosed bastard, but if you read my post again, you'll note that I have feathered valves for real... it is mentioned. The situations (it's happened a couple of times) were not sterile and neither was in a pool. A couple of real-life situations in very different conditions but the gas I was preserving was required for quite considerable decompression obligations. These experiences inform my behavior now. Not much of what I teach and write about is bull**** I have not tried.... except when I write about F1 racing.

Based on those experiences, and feedback from others to whom I've promoted "feathering," I firmly believe the skill is a valid one, and I insist that anyone who trains with me these days is aware of that. Of course, you do not have to accept my opinion or those data, and you are free to do as you please. But please if you are going to dismiss it, at least tell us why and give examples... or admit you may need to rethink or reassess...

---------- Post added September 25th, 2013 at 06:34 AM ----------

I did some valve feathering in my recent class. I would imagine you could get good at it, but at my level of facility, I sure wouldn't want to depend on it for much gas that I really needed.

Then my advice would be to practice it, because it is a very useful option for anyone (SM, BM, CCR) who may need to preserve gas in a bottle slung by their side.

It's a pass/fail skill in a SM class but I make it so in ANY class that uses a "stage" or deco bottle.

 

[Peter69_56]

So Doppler says it doesn't significantly impact (significantly) on a platform (pretty pool like) and then Peter gives some info about a real life situation. Steve, drills and sterile environments aren't what I'm talking about. I'm talking about real deal stuff.

Peter, I'd love to hear more details, really. That's the kind of stuff I'm interested in. You said deco reg, shallow, deep, how much reserve, nature of failure, etc etc. All important details.

Ok quickly it was a 55m dive with blue water ascent in current, with reasonable surge. The 50% deco reg free flowed on activation and would not stop. It was recently serviced and had been pier tested.

Not having the deco gas available would have made my reserve tight so it was in my best interest to get as much out of it during deco as I could so I still had reserve back gas.

 

[DaleC]

Just to clarify my last post. I believe all skills are good skills and the more tools you have the better. I was referring to some as being "unnecessary" simply in terms of achieving the particular end goal I was discussing.

 

[TSandM]

Being that this was posted in the technical diving specialties subforum, I would assume we're talking about dives with either a virtual or real overhead, not solo recreational dives. Any time the surface isn't an option, I personally think that strategies that maximize gas reserves ought to be the ones chosen to solve problems.

Steve, feathering is only one of the MANY things I need to practice in my sidemount gear. At the moment, not only would I not approach a cave in it, but I think I'm marginally safe in shallow open water!

 

[AfterDark]

Being that this was posted in the technical diving specialties subforum, I would assume we're talking about dives with either a virtual or real overhead, not solo recreational dives. Any time the surface isn't an option, I personally think that strategies that maximize gas reserves ought to be the ones chosen to solve problems.

Steve, feathering is only one of the MANY things I need to practice in my sidemount gear. At the moment, not only would I not approach a cave in it, but I think I'm marginally safe in shallow open water!

Since solo diving is in the tech specialties that assumption may not be entirely correct. IMO ID's and SM are reasonable choices for OW solo down to whatever depth the bottom may be, within OC limits.

 

[DaleC]

I concede that the solo application may not fit the "tech" definition but as AD says, that's where we find ourselves.

I also think it's relevant in a sense as many on the board subscribe to the concepts of standardization and beginning with the end in mind so a dismissal of ID's here could lead to the inference that they have no place anywhere along the diving continuum.