Inverted twin cylinders

[TX101]

CONS:

- It's unnecessary. You're relying on equipment to solve a skill issue, since there's no real reason not to be able to reach your valves in a traditional configuration, therefore rendering everything else I'm about to type unnecessary.

- the need to purchase brand new hoses for everything, since the lengths will be different.

- no real clean way of routing the hoses. For example, with a traditional setup, your backup reg curls right under your head and chin - you couldn't do this with an inverted set.

- the need to purchase a manifold cage to protect your valves... which you really, really hope works when you set a 100 lb set of doubles on a rocking boat down on the cage.

- streamlining would go to absolute crap if you had aluminum cylinders or steel tanks with boots on.

- the need to spin a 100 lb set of doubles around for fills, storage or inspection.

- shutting down your isolator (which is arguably the most important valve) would be even tougher, since you'd have to reach around the tanks to do it. If you were to add slobwinders, it's an additional failure point to deal with.


PRO's

- I suppose if you were lazy and didn't invest the time to learn how to do a simple valve drill, you could rely on equipment to 'solve' a skills issue. But - it's not really solving anything is it?

"Normal Twinset"

CONS:

- It's unnecessary. You're using convention to dictate your gear choices. Why try to contort yourself and break your shoulderds when you don't have to? relying on your ability to reach behind you is unnecessary, since inverting makes it *much* easier to reach the valves.

- the need to purchase brand new hoses for everything.

- streamlining is worse, since you have regs and hoses at the front of the twinset, behind your head. If you invert, you present a nice round profile to the water, similar to a torpedo.

- shutting down your isolator (which is arguably the most important valve) would be even tougher, since you'd have to contort your arm even more, rather than just spinning the 'slob knob'.

- More of an entanglement hazard. Since most of the time you are swimming forwards through the water, you have a greater chance of getting your first stages tangled (eg. in monofilament line). Inverted twins cant get tangled, because there is nothing to tangle.

- A greater possibility of roll-off inside a cave/wreck and if you are passing a restriction that dosen't physically allow you to put your hand behind your head, bye bye gas.

PRO's

- I suppose if you were lazy and didn't invest the time to learn about different kit configurations and just went with whoever on the internet says is the best, you would end up mounting your doubles 'right side up'.


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And saying the slob knob is adding another point of failure is like saying adding another cylinder is adding another point of failure. Sure it is, but for some people the benefits outweigh the increased failure points.

I also want you to know that I personally dive 'right way up' twins, but I have no problem with other people diving inverted twinsets and feel no reason to berate them for their choice

 

[Boogie711]

LOL - OK TX101, you tell me what's safer - building the skill set to be able to manipulate your valves on your own, or relying on a piece of equipment for a mission critical application like a valve shutdown, and having it come offin your hand?

Personally, I never want equipment to substitute for skills. That's a one-way ticket to a world of hurt I don't want.

Thanks for your contribution.

 

[TX101]

LOL - OK TX101, you tell me what's safer - building the skill set to be able to manipulate your valves on your own, or relying on a piece of equipment for a mission critical application like a valve shutdown, and having it come offin your hand?

Personally, I never want equipment to substitute for skills. That's a one-way ticket to a world of hurt I don't want.

Thanks for your contribution.

When you close the manifold, regardless of whether it has a slob knob or not, you are "relying on a piece of equipment for a mission critical application like a valve shutdown".

I agree, a slob knob has more potential points of failure. But so does a twinset compared to a single cylinder. So does a balanced/captured o-ring style manifold vs a unbalanced/facing o-ring manifold. But I'll chose the "non-DIR" balanced manifold with a twinset every day of the week because opening and closing the valves is made easier.

 

[sparky30]

LOL - OK TX101, you tell me what's safer - building the skill set to be able to manipulate your valves on your own, or relying on a piece of equipment for a mission critical application like a valve shutdown, and having it come offin your hand?

Personally, I never want equipment to substitute for skills. That's a one-way ticket to a world of hurt I don't want.

Thanks for your contribution.

Who is substituting anything? I can do a valve shutdown 'right side up' like every body else.. Its not a big deal.. its does however require me to contort myself into pretzel shape behind my head.. Not the most comfotable position..
I think TX101 made some valid points.. the setup would be more streamlined.. I could think of any number of ways to route hoses the would almost eliminate the entanglement hazard all together.. The right side up setup is more of a hazard in tight quarters and less streamlined. Sure.. it involves flipping your tanks to fill them.. and yes I would need new hoses.. but.. all those things happen out of the water.. in a tight spot when I need to get at the valves I bet its easier.. Time to expand you mind and think outside the box.
Hmm.. I might have to try the upside-down setup to see it first hand..

 

[Boogie711]

Sparky - go ahead and do a valve shutdown without a slobwinder on an upside down set of doubles and let me know how it works. Honestly - I'm curious.

I'm also curious how you're going to get custom hoses just to try everything but hey - to each his own. I wouldn't dive with you, but I know that sure as heck wouldn't stop you.

You asked for an appraisal, I offered them for you, but if you're bound to go ahead and try, then good luck to you.

Thanks.

 

[Dive Source]

I wouldn't dive with you, but I know that sure as heck wouldn't stop you.
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This is a likley a very large list by the way......

BTW - Thinking outside the box is something rarely encouraged at SB.
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(wow - I haven't taken a poke at the boogie man in a while - god that felt so gooooood)

 

[Mr Adams]

Hi

Wow! I didn't expect this much controversial debating on this topic, but you all have good reasons for liking or disliking the inverted cylinder configuration, but regardless it looks like the Europeans have been inverting there tanks for years with out incident. I think its kind of like the Din valve when it first came a shore were it was looked at as nuts because of possible shearing but now its main stream.

Mr A

 

[Boogie711]

Hey Brian, if it makes you feel any better, I won't dive with you, either. Besides, I don't like when OMS stuff comes in contact with my skin.

Just kidding, but I didn't want you to feel left out.

 

[MikeFerrara]

This is a likley a very large list by the way......

BTW - Thinking outside the box is something rarely encouraged at SB.
.
.
.
.
.
.
.
(wow - I haven't taken a poke at the boogie man in a while - god that felt so gooooood)

As Mr. Adams points out, upside down tanks aren't new, novel or thinking outside the box.

 

[TX101]

Sparky - go ahead and do a valve shutdown without a slobwinder on an upside down set of doubles and let me know how it works. Honestly - I'm curious.

I think it goes without saying that you need one if you are diving with an isolation manifold.

I'm also curious how you're going to get custom hoses just to try everything but hey - to each his own. I wouldn't dive with you, but I know that sure as heck wouldn't stop you.

You can get hoses cut to length - well, I can over here.. I assume you can in the US too.

As I said previously, I dive right-way-up doubles. However, if I was going to invert, I would probably chose independents - which means there's less failure points (therefore arguably much safer) and also takes the isolation/slob knob argument out of the equation.

I think the decision to invert is about as risky as the decision to dive independents/manifold + isolator/ straight manifold argument. It's "whatever works for you". Okay, it's not DIR/Hog/whatever.. but so what? Just because it's the best way for someone else dosen't mean it's the best way for you.

I assume you wouldn't dive with someone who's inverted their cylinders because you are DIR (I don't keep track of who is & who isn't) and want to dive with someone who has exactly the same config? Or do you truely believe that inverted twins are unsafe? I find it hard to believe you would tell a SEAL military diver you wouldn't dive with him because he will kill himself with his current gear configuration.

Actually, thinking about it.. recreational scuba divers are the only divers that wear their cylinders right way up. Military & commercial divers as well as firefighters, etc. all wear them inverted. Maybe us recreational guys are getting it wrong?

(actually, I think the real reason they do it on land is because gravity is pushing down on the cylinders, making it impossible to reach the valves behind their head)