double tank equipment

[Adobo]

You are right: I wrote that "competent" instruction was not necessary and I meant "formal", more specifically formal training requiring that a fee be paid.

Did not intend to imply that anyone in this thread was selling anything, or that your opinions were based on financial gain.

"Your high horse", "bragging rights" and the implication that I haven't spent money on formal instruction are inflamatory bluster and not constructive.

So you are okay with us recommending that a newer diver wanting to dive doubles to attend a workshop for as long as its free. If the same workshop is being offered but the attendees are asked to help offset the workshop leader's expenses, then you have a problem. Is that right?

 

[Adobo]

Bringing other elements, like NDLs, buoyancy problems associated with major changes as large volume tanks are emptied, Nitrox, neoprene suit compression, or similar issues muddies the water and supplies contrived and false support for an untenable position.

If I understand correctly, your position (and a few others) is that if a diver were going from something like an aluminum 80 to a steel 130, a diver with basic open water certification should have been trained sufficiently such that whatever the differences between those two tanks, the diver should be able to adapt without further instruction (formal or informal, paid or free). And I can appreciate that.

And I think you are saying that by extension, going from a single 80 to double 80s should really be no different than the scenario above.

Where we disagree is that the latter is different than the former. Some of the differences include:

• the latter has a manifold (at least, that is the common set up I have been seeing the time I have been diving and in the various locations I have been diving)
• the latter changes the geometry of how the regulators are mounted relative to your mouth, your BC inflator and wherever it is that you typically keep your SPG. This means, at the very least, that the hoses that are currently on the regs, the inflator, and the SPG will now have to be swapped out. More than likely, the diver will also opt to add a second first stage. This means that not only are hose lengths in question, now we are also talking about where does each reg get mounted, where does the SPG get mounted, how do we route the hoses and so on.
• there is also this notion of matching the exposure protection to the tanks (or conversely, matching the tanks to the exposure protection).

There's a few more points that I won't bother with since the above are already difficult to get consensus on.

What I will says is this:

• as we collectively discovered the other day, there is more to a manifold than what you (disinterestedly) see in a fill station and what you can intuit from a glance at a schematic.
• there are no heuristics provided in today's basic open water training that would allow a diver deduce how to configure regulators for doubles usage.
• whether or not we agree on the last point, the fact of the matter is this, a lot of open water trained divers are overweighted when we get in the water. I think there were at least one if not two fatalities this week alone where the diver being overweighted contributed to the diver's eventual demise. This problem only multiplies when the diver transitions from a single tank to a doubles rig which are not matched to their exposure protection.

Its been suggested by some that these concerns and all other important considerations are so trivial that they can be addressed within a 5 minute discussion with half competent dive shop employee.

I propose that if someone who has decades of diving experience can miss some of the finer points of a manifold after the disinterested glance at the dive shop and the quick review of the schematic, then it would behoove a newish diver to have this discussion, not with a half competent dive shop employee but rather with someone who has extensive experience diving doubles. Or absent that, to attend a workshop that discusses this topic.

All the other stuff.. the name calling, the questioning of the character or motives of people who have absolutely nothing to gain, that's the stuff that muddies the validity, or the lack thereof, of the various opinions being shared.

 

[agilis]

I think I covered what I think a competent diver would do before after obtaining an isolation manifold and intending to use it.

I wrote that I'd spend time examining it, learning how it functioned by: reading manufacturer's instructions, reading the experiences of others, setting it up on land until I felt well acquainted with how it all goes together, and using it cautiously in the water the first few times until I felt comfortably familiar with it. That's what I do with any new equipment with significant differences from what I'm used to.

I think this is what most experienced divers do. It's not rocket science.

 

[Patoux01]

One could argue that "two valves" could be the manifold and the one that you're filling?

---------- Post added June 21st, 2015 at 01:51 PM ----------

Ah no, he said both tank valves. My bad!

 

[cool_hardware52]

Agilis: Both tank valves do need to be open.

Uh, no, not they do not.

One more time. To fill a set of doubles:

Connect a fill whip to a *single* post

Open this post valve and the make sure the *Isolator Valve* is also open, if the manifold is equipped with a Iso valve.

This will allow gas to enter *both* cylinders.

If you open the *other* tank (post) valve the gas will escape, you know make a real loud noise and blow stuff around in the fill station.


The *only* function of the "post" valves is to control the Orifice in that post, i.e. supply or interrupt the gas to the reg attached to *that* post.

This is true regardless of the presence or absence of an Isolator valve.

The center bar of the manifold connects to a port on the Post valve that communicates directly with the interior of the cylinder. The post valve does not, and cannot interrupt the flow between cylinders and the manifold.

This is an actual *fact* regardless how "manifestly obvious" your extensive diving experience, amateur plumbing back round, review of the schematics or disinterested observation of filling procedures lead you to conclude otherwise.

Tobin

 

[PfcAJ]

It's poor form to pontificate about subjects in which one has no experience.

If you don't know how a manifold works, should you really be arguing about how they work with people who do understand how they work?

 

[FinnMom]

So you are okay with us recommending that a newer diver wanting to dive doubles to attend a workshop for as long as its free. If the same workshop is being offered but the attendees are asked to help offset the workshop leader's expenses, then you have a problem. Is that right?

No. My idea was more along the lines that such a workshop might even exist.

Even with a fee the workshop is likely to be a less expensive option than formal training. By comparison "formal training" might be for example, IANDT's Intro to Tech. It looks like an excellent course and is probably worth every penny, but it isn't cheap and it isn't required for a certification.

I also mentioned books. You can also learn much from a book that a formal class would have taught in the classroom., but books are not likely to be free either. Then again the real winner in this "diligent reader" strategy is that when you do take a class you need for certification, you will understand much better, retain more and very likely have the time to discuss other topics you never would have gotten to if you had come in only as prepared as the average student.

 

[Adobo]

No. My idea was more along the lines that such a workshop might even exist.

Even with a fee the workshop is likely to be a less expensive option than formal training. By comparison "formal training" might be for example, IANDT's Intro to Tech. It looks like an excellent course and is probably worth every penny, but it isn't cheap and it isn't required for a certification.

I also mentioned books. You can also learn much from a book that a formal class would have taught in the classroom., but books are not likely to be free either. Then again the real winner in this "diligent reader" strategy is that when you do take a class you need for certification, you will understand much better, retain more and very likely have the time to discuss other topics you never would have gotten to if you had come in only as prepared as the average student.

Such a workshop does indeed exist. At least two training agencies offer it.

Of course, one could likely solicit the help of a doubles knowledgeable mentor - to talk through some of the key points over lunch and a couple of beers. At the end of that process, one would have paid as much as you pay for a workshop. And likely, the mentor will not have gone through the topics in as organized or as detailed a manner as the person who prepared and put together the workshop.

I can appreciate that some people don't see the *need* for such a workshop or a chat session over lunch just to learn about doubles. I *learned* to dive doubles on my own also. But not really on my own since I had the benefit of a huge doubles diving community and a book called "Dress for Success" that covered a lot of the material. I suspect the original poster is not as lucky - just judging by how the question was posted.

 

[AfterDark]

Lets examine in detail the evolution of agilis understanding of *one* aspect of diving doubles.

First he clearly states that operation of manifolds are "manifestly obvious" and the need for instruction "comical"

Then he exposes his total lack of understanding of how they work.

Shortly after he has the benefit of a bit of "informal" but spot on instruction. Briefly he appears, between the excuses and CYA dance, to have acquired a clue.

Then he again grenades and displays in detail that the informal online instruction he received here free of charge was glaringly ineffective.

Honest folks agilis is not my sock puppet. He exists. I didn't invent him to make my point…...


Tobin

So you're happy with one example to make your point? Pretty low threshold of proof IMO. One diver out of unknown thousands that's all it takes to make you happy? I don't recall any part of my training that involved fill tanks other than hydro vip and working pressure. So your one example didn't know the details for filling manifold doubles. Big deal! A clear and present danger to the safety of diving! LOL

 

[cool_hardware52]

So you're happy with one example to make your point? Pretty low threshold of proof IMO. One diver out of unknown thousands that's all it takes to make you happy? I don't recall any part of my training that involved fill tanks other than hydro vip and working pressure. So your one example didn't know the details for filling manifold doubles. Big deal! A clear and present danger to the safety of diving! LOL

Again you have missed the point. It's not really about manifolds, it's about need for and the value of "competent training" agilis was supremely confident in his (incorrect) knowledge and unreachable via informal means. Sit in my chair for a week or two and you will discover agilis has many brothers…..

Tobin