Hose routing on independent twin setup?

hi all

I need some assistance on hose routing for independent twins. if each cylinder has it's own primary and secondary 2nd stage, how are these routed and clipped?

Is there any need for me to use a second 7ft hose if i'm already using one on the one of the cylinders?

Any assistance on this would be much appreciated as i've tried searching but cant seem to get anywhere with this.

cheers
Jeelan

I personally use the same setup for back mounted independent doubles as I do for manifolded doubles, except I add the extra SPG to the right post. i.e. only one second stage per tank. But I use independents rarely - only when manifolded twinsets haven't been available.

I've meant to start using an o-ring, instead of cave line, to attach the boltsnap to the primary second stage so that it could be ripped off when clipped off without fumbling to unclip it in an emergency.

The advantage of using two 7ft hoses would be that you could always hand off the reg you are breathing in an emergency, whereas with my setup I would hand off the clipped off reg if the OOG occurred when I was breathing the short hose. (I alternate between the long and short hose regs to breathe the tanks down roughly evenly using the thirds rule).

As above but make sure that the SPG's are not the same. You have to be able to tell them apart at a glance.

The key to doing independents to to take each tank down 500 psi and switch over. You will need to get chacking the gages, reading them, and understanding them at a glance. Many people can not put all three together.

Gilldiver:

As above but make sure that the SPG's are not the same. You have to be able to tell them apart at a glance.

The key to doing independents to to take each tank down 500 psi and switch over. You will need to get chacking the gages, reading them, and understanding them at a glance. Many people can not put all three together.

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I have the same SPG's, but I can tell them apart because the one for the left tank is clipped to the left hip D-ring and the one for the right tank is clipped to my right hip D-ring (Bryden buckle).

For gas planning, I start with the right tank (shorthose) and breathe a third of it, then switch to the left (longhose) and breathe 2/3 of it, and then back to the right tank. This way the tanks are never more than 1/3 apart in remaining gas, and I generally only need to make 1, or at most 2 switches. I usually have at least a third left in each tank at all times so in OOG situation both tanks would have enough for one person to make it out.

How you rig and breathe from them depends on how you use them. In my case Independent Doubles are Not a substitute for manifolded doubles. They are a way of carrying extra gas for certain dives while traveling and so I don't have to tote a pony with me. In short Independent Doubles, to me, are nothing more than a full size tank with a full size pony that I don't have to worry about getting through TSA.

I use my normal doubles rigging. I breathe off the primary tank just like I normally do when diving singles. There are other ways. But this saves having to change rigs and allows me to dive essentially the same setup all the time.

On the other hand, if you are looking at these to be a substitute for manifolded doubles I urge you to do some more checking.

*Floater*:

I personally use the same setup for back mounted independent doubles as I do for manifolded doubles, except I add the extra SPG to the right post. i.e. only one second stage per tank. But I use independents rarely - only when manifolded twinsets haven't been available.

I've meant to start using an o-ring, instead of cave line, to attach the boltsnap to the primary second stage so that it could be ripped off when clipped off without fumbling to unclip it in an emergency.

The advantage of using two 7ft hoses would be that you could always hand off the reg you are breathing in an emergency, whereas with my setup I would hand off the clipped off reg if the OOG occurred when I was breathing the short hose. (I alternate between the long and short hose regs to breathe the tanks down roughly evenly using the thirds rule).

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Thanks all, as per Floater's comment that a second 7ft would be a good idea incase of OOA occurances - how would i route the second 7ft hose? Would it basically follow the same routing as the "normal" 7ft hose ie down my right side, tucked under a cannister, over my left post, round my neck and hang of my right side. It may come up a little shorter given that it's starting from my left post and has that much more distance to travel.

good point about the SPG being different as well -

Generally - is there a NEED to have independent twins unless as ArcticDiver stated - one of the cylinders is basically a substitute for a pony??

the reason i'm asking is because i recently signed on for a dive expedition to Antarctica in 2008 and i got the itinerary and dive schedule. The Divemaster's comments regarding equipment configuration is that we need to be diving independent twins for redundancy - Max dive depth is only 25m but 2 sets of regs are required incase of freezing due to water temp. Given this, i can understand the need for 2 regs so that one can be a redundancy but i would have thought that 1 cylinder with a H valve would be enough.

Thanks again for everyone's comments

cheers
Jeelan

jeelan:

.... The Divemaster's comments regarding equipment configuration is that we need to be diving independent twins for redundancy - Max dive depth is only 25m but 2 sets of regs are required incase of freezing due to water temp. ....

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This is crazy. I would use an isolator manifold if this is the reason given. My first choice would be to find a different operation that knew what they were doing. Diving in extreme cold with independent twins is adding unneccessary task loading which could be the difference between safe and sorry..

The only independants I've ever dived were side mounts and that's the way I'd do it. If they have to be independant, there's no reason you need them right next to each other and you don't need them on your back. Some of the sidemount guys have a saying..."Your valves belong in your arm pits". LOL

I don't think two 7ft hoses give any benefit.. It is too much burdon and bulky. Even, one 7ft hose is a relatively short history in a rec. diving range. Don't get me wrong with other diving philosopy. Many rec. divers are still using a 29 inch primary and 36 inch Octo set up. If we are talking about a redundancy and safety, it is endless... Just stay at home.

jeelan:

the reason i'm asking is because i recently signed on for a dive expedition to Antarctica in 2008 and i got the itinerary and dive schedule. The Divemaster's comments regarding equipment configuration is that we need to be diving independent twins for redundancy - Max dive depth is only 25m but 2 sets of regs are required incase of freezing due to water temp. Given this, i can understand the need for 2 regs so that one can be a redundancy but i would have thought that 1 cylinder with a H valve would be enough.

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Diving in Antartica is a very speclized project and you have to do it the way the dive supervisor wants it, or you just don't go. Here is the link to McMurdo Sound that is a few years old but nothing has realy changed. They use large singles with Y valves. Make sure you look at the gearing up section and the photo of the 1st stage with about 1" of ice on it. With these conditions two regulators are a must, but I would go with the large single over independent doubles. McMurdo also has a zero deco diving rule.

http://scilib.ucsd.edu/sio/nsf/diving/index.html

Also of note is that they do not use a line back to the hole as the water is so clear at 200'+ vis that any safety benefit is out weighted by the potential entanglement risk. You just do get so far away from the hole that you can't see it or the safety hole.