Indie Doubles - What the??

[kanonfodr]

I've been reading a lot of the discussions of independent twins, and a lot of SBers tend to espouse the idea that one can go on a dive trip, rent a pair of AL80s and run them as IDs. Groovy, that's a pretty wikked idea except for one small detail that I've either got the wrong idea on, or folks are just not mentioning all the facts.

When you go renting AL80s and band them up as indie twins, what the hell do you do for a valve drill? The right post I understand completely, but most of the AL80s I've come across use a valve on the right side, leaving your left tank (IMO) unreachable in case of valve failure.

A possible solution I see is to reverse the left tank so the valve is pointing to the left, but that raises an eyebrow towards streamlining (and it probably looks just funk, but nonetheless you could reach the valve to perform a shutdown.

The other solution I see is to just say screw it, run as little as possible off of the left tank, and possibly breathe that one down first so you can maximize your gas versus the risk level.

This all assumes you aren't renting from one of the possibly 5 dive ops in the world that has left-handed valves on some of their AL80s.

Peace,
Greg

 

[Codyjp]

If you did blow a second stage or hose why would you need to bother shutting down the valve? Either way the gas is a gonner.

I'd like to do some side mount training at some point because it would be great at places like Bonaire!

 

[LiteHedded]

If you did blow a second stage or hose why would you need to bother shutting down the valve? Either way the gas is a gonner.

I'd like to do some side mount training at some point because it would be great at places like Bonaire!

good reason NOT to use them in the first place

 

[jtivat]

Or just bring a stage kit and sling an 80.

 

[DaleC]

In another thread someone suggested bringing the manifold and bands with them on vaca but I wondered (as the OP here did) whether resort operators have left/right valves that would fit a specific sort of manifold. It's odd that no manifold proponents challenged that one isn't it???

I wonder what sidemounters do on vaca. Do they have left/right valves or do they just have one first stage sticking out where it can get knocked about? I'm going to ask in the sidemount section as now I am curious too.

Here's the link Kanonfodr if you are interested in the responses: http://www.scubaboard.com/forums/side-mount-divers/320315-left-right-valves.html#post4986407

It is a problem that one has to consider. No system is perfect. Some people say it doesn't matter if you shut down the post but I like having control of my rig so I went out and bought a lefty K valve.

 

[Colliam7]

If you did blow a second stage or hose why would you need to bother shutting down the valve? Either way the gas is a gonner.

Not entirely true. Depending on the circumstances, and your equipment, you may be able to change regs in an emergency. You shut down the valve to save the gas, then if you reach a point in the dive where you must use that gas (an unlikely situation, but not impossible), you could 1) change a reg from a pony, or deco bottle to the partially full one, or even more extreme 2) change the good reg from the empty tank to the one with gas. The latter is not necessarily easy but if there is no other alternative, it is possible. Certainly, if you have a reg fail on one of the tanks, depending on your dive plan and profile, you may end up calling the dive, beginning your ascent to you first deco stop, or continuing your dive until you reach your pre-determined minimum gas and then ascend normally, etc.

good reason NOT to use them in the first place

Possibly. If you are diving where you have access to manifolded doubles, that would be a preferable way to go for most of us. But, independent doubles have their place.

I'd like to do some side mount training at some point because it would be great at places like Bonaire!

And, a pefect example of why independent doubles, whether backmount or sidemount, have more than a little appeal. You may be in a situation where manifolded backmount doubles are simply not available, yet, you want to have more gas. I previously thought it would be useful, and not terribly weight-burdensome, to carry a set of tank bands to Bonaire, or similar locales. Once I started SM diving, it became a non-issue.

I wonder what sidemounters do on vaca. Do they have left/right valves or do they just have one first stage sticking out where it can get knocked about?

The latter, except for the 'get knocked about' part. I periodically use a couple of standard AL80s, because they are convenient. Yes, one of the valves is not where it should be, but I am not diving in such tight spaces that there really is any problem.

 

[Mark Michaud SELAUSAR]

In another thread someone suggested bringing the manifold and bands with them on vaca but I wondered (as the OP here did) whether resort operators have left/right valves that would fit a specific sort of manifold. It's odd that no manifold proponents challenged that one isn't it???

I wonder what sidemounters do on vaca. Do they have left/right valves or do they just have one first stage sticking out where it can get knocked about? I'm going to ask in the sidemount section as now I am curious too.

Here's the link Kanonfodr if you are interested in the responses: http://www.scubaboard.com/forums/side-mount-divers/320315-left-right-valves.html#post4986407

It is a problem that one has to consider. No system is perfect. Some people say it doesn't matter if you shut down the post but I like having control of my rig so I went out and bought a lefty K valve.

Opposing valves in sidemount is more of a preference than really necessary. My s/m 80's are both right or left handed (never can remember). If you can't manage valves in this manner than sidemounting is not for you. In other words, it is easy both ways. Unless you are scootering and run into someting you will not damage your valves, no matter how you have them. If you are in a low sandy area you may want you handles moved to keep the sand out so they do not get stuck, but other than that, and in the context of this thread, it doesn't matter. Reaching a valve facing in, out, up or down is easy enough.

 

[AndyNZ]

In another thread someone suggested bringing the manifold and bands with them on vaca but I wondered (as the OP here did) whether resort operators have left/right valves that would fit a specific sort of manifold. It's odd that no manifold proponents challenged that one isn't it???

When I take my manifold, I take the whole caboodle.... valves, manifold and band.... the only two concerns are:

1. Are the tanks 3/4" or are they 25mm.... my valves are 3/4", which as fine for most places, but it's easy to check in advance.

2. Are the tank diameters ok for the tanks - my bands, for example, are for steel tanks rather than AL80s, so they don't fit most resort tanks. That's why I have a second set of bands for AL80s that just sit in a box until it's holiday time.

 

[Gombessa]

In another thread someone suggested bringing the manifold and bands with them on vaca but I wondered (as the OP here did) whether resort operators have left/right valves that would fit a specific sort of manifold. It's odd that no manifold proponents challenged that one isn't it???

I don't whoever said that meant to just take the isolator bar, you'd need to bring the left/right valves as well. Just having the isolator bar would mean you're relying on a resort operator to carry valves that are 1) L/R paired, 2) made for a manifold and plugged and 3) perhaps DIN. I don't think anyone would pack a partial doubles setup and assume any of these are the case without checking beforehand.

 

[ianr33]

I've used independent doubles on a trip to Cayman. Had the left tank normal way round.I can reach the valve like that but its difficult. If I did it again would likely turn the tank round so the valve points left.

Basic dive plan was 40 minutes at 100 feet or 1500 psi in each tank before turning (nitrox32). We had some awesome dives doing this. After profiling back to shore some dives were 90 minutes long. Wasn't too worried about losing gas. 40cu ft was plenty for the minimal amount of deco we were doing.