independant 12s vs Manifolded..

[debman]

I am only a wee sports diver so take what i say with a pinch of salt but this is my wee opinion.i have thought a lot about mani vs non mani twins.

i dive on non-mani twin 10s. this is mainly because i borrow them from the club and the club dont have mani ones, but even if i bought i dont know that i would buy mani cyclinders.

my reasons are that with manifolded twins:
you HAVE to be able to shut the manifold very quickly otherwise you have no air in either tank. (unless you have a stage/pony obviously)

however for me (remember my depth is limited to 35m) i like non-mani better.

if one cylinder goes then i will get my buddy to turn it off: will be a bit scary but no panic about running out of gas.
I will always plan to have enough gas to get up and do saftey stops with one cylinder. for me that is an important reason for diving on twinsets.

it is just personal opinion but i like that i wouldnt have to KNOW that if sh*t happened then i WOULD definately in a panic situation be able to turn off the manifold very quickily. you never know how much air you will lose whereas in with non-mani atelast i know i would have my min set bar in one cylinder.

surely if a cylinder went, youd come up: whether mani or non-mani.

i guess my theory may not hold if you are going very deep though!

cheers

debsx

[Ferg3333]

IMVHO manifolded is the safer alternative.

My reasoning why manifold is better than indies:

On indies a reg goes and you lose a cylinder and if your planning thirds at worst case you will have 1/3 of a tank or 1/6th of your total gas supply to get home therefore on indies I would probably run a rule of sixths. Although you could take off your tanks and swap regs, you better be good at holding your breath when the tank is empty and pray that the reg you just flooded will work.

worst case is breathed two thirds from one tank just switched to other tank where you have a planned third left to breathe (granted you should be on your way home already) you now only have 1/6 of your original supply to get you home, where you intended or planned to use 1/6 this is cutting it rather fine. AND YOUR ON YOUR OWN

Whereas on a manifolded twinset you would have access to all your gas after isolation, close reopen. so 1/6 to get home or 1/2 (1/6 +1/3) of your total gas supply I know where I would rather be. Especially as your RMV will rise from the reg going unless you are super calm and relaxed.

So buy some bands and a manifold, get someone to show you how to use it properly.

[TerryH]

Originally Posted by Ferg3333

IMVHO manifolded is the safer alternative.

My reasoning why manifold is better than indies:

On indies a reg goes and you lose a cylinder and if your planning thirds at worst case you will have 1/3 of a tank or 1/6th of your total gas supply to get home therefore on indies I would probably run a rule of sixths. Although you could take off your tanks and swap regs, you better be good at holding your breath when the tank is empty and pray that the reg you just flooded will work.

worst case is breathed two thirds from one tank just switched to other tank where you have a planned third left to breathe (granted you should be on your way home already) you now only have 1/6 of your original supply to get you home, where you intended or planned to use 1/6 this is cutting it rather fine. AND YOUR ON YOUR OWN

Whereas on a manifolded twinset you would have access to all your gas after isolation, close reopen. so 1/6 to get home or 1/2 (1/6 +1/3) of your total gas supply I know where I would rather be. Especially as your RMV will rise from the reg going unless you are super calm and relaxed.

So buy some bands and a manifold, get someone to show you how to use it properly.

I've just spotted the flaw in your cunning plan
"Whereas on a manifolded twinset you would have access to all your gas after isolation,"

[MATTBIN]

Originally Posted by Ferg3333

IMVHO manifolded is the safer alternative.

My reasoning why manifold is better than indies:

On indies a reg goes and you lose a cylinder and if your planning thirds at worst case you will have 1/3 of a tank or 1/6th of your total gas supply to get home therefore on indies I would probably run a rule of sixths. Although you could take off your tanks and swap regs, you better be good at holding your breath when the tank is empty and pray that the reg you just flooded will work.

worst case is breathed two thirds from one tank just switched to other tank where you have a planned third left to breathe (granted you should be on your way home already) you now only have 1/6 of your original supply to get you home, where you intended or planned to use 1/6 this is cutting it rather fine. AND YOUR ON YOUR OWN

Whereas on a manifolded twinset you would have access to all your gas after isolation, close reopen. so 1/6 to get home or 1/2 (1/6 +1/3) of your total gas supply I know where I would rather be. Especially as your RMV will rise from the reg going unless you are super calm and relaxed.

So buy some bands and a manifold, get someone to show you how to use it properly.

The big question here is is "IF" you can save the gas, Diver magazine did a test a while ago, 7's forget it, 10's marginal, 12's if you are quick enough. Sometimes though a manifold set will lose everything, if the manifold blows at one of its O rings you loose the lot, very rare admitted. Each to their own. I always plan on using one cylinder to get me home, regardless of manifolded or not. I am not biased either way by kit, I have both, each has advantages, each has disadvantages. We normally save this discussion for winter by the way

Matt

[MATTBIN]

Originally Posted by JasonP

Manifolded sets are easier to configure to gas share with if your buddy runs out of gas, especially in a restricted, overhead environment.

And you should be able to get access more of your gas in the event of a regulator failure.

However, the manifold is an, albeit unlikely, single point of failure.

So diving in pairs/teams, manifolded sets have the advantage. Diving solo, especially in overheads where you could damage the manifold on the ceiling, independents are better. And side mounted independents are even better as you can definitely get at the valves.

Jason

Nice reasoned post.
Matt

[big_si]

Originally Posted by Ferg3333

AND YOUR ON YOUR OWN

Why are you on your own?


Won't your buddy with you with extra gas no matter whether you have 1/2 or 1/6 or less?


I did about a year on indies (12's and 15's with handed valves)as my intro to twins... Generally they were fine.

It was only really whilst doing courses and distracted with drills and "issues" to deal with that the switching between regs went out the window and ended up with no gas in 1 cylinder and no inflation.... Also found it an issue dealing with donating a reg in a hurry if on the wrong reg....

After that I thought that in a real " 5hit / fan situation" I wouldn't want the extra hassle of having to think about those bits and pieces so moved to a manifolded set. (I could shut down my knobs on the indies anyway so ability to shutdown wasn't a factor for me.)

That's my 2p

[Steve S]

There are drawbacks with every system the biggie AFAIC with indies [and I dived them for years] was that you have to be very disciplined with reg swapping to ensure you breath them down evenly.

My advice would be to dive them as indies while you decide what's best for you.

Safe diving,
Steve

[garygonediving]

Unmanifolded are a right PITA for the bloke who has to fill them. And may occasionally find themselves left 'til last because of this. Maybe.

[Ferg3333]

Originally Posted by big_si

Won't your buddy with you with extra gas no matter whether you have 1/2 or 1/6 or less?

Its worst case scenario, I have surfaced alone before now, for many a good reason i.e. current running shots been pulled down crushed and is now sinking with 30mins of deco to do.

Irrespective of the diver magazine test, if the risk benefit didn't balance everyone would be diving indies. The only failure that would lead to a complete loss of gas is if the valve broke, if you lose an o ring at one cylinder end (left post say) you can isolate the gas in the middle and then still have access to the gas in the right post. If both go your f****d without a paddle. But then what would be the flow rate out of the cylinder???

Also as for isolation, if you have the set configured correctly and once proficient you can shut down the freeflow in less than 10secs. Using both hands one on the isolator and one on the offending post. Then reopen the manifold and all is good. hopefully The problems come when you have to do the full drill and once good this can be done in about 30-45 secs I reckon. I never timed myself when I was on OC.

[big_si]

Originally Posted by Ferg3333

Its worst case scenario, I have surfaced alone before now, for many a good reason i.e. current running shots been pulled down crushed and is now sinking with 30mins of deco to do.

[DIR mode] with proper buddy skills this wouldn't be a factor [/DIR mode] ( But still I keep the probe away from me!!! )

Originally Posted by Ferg3333

Irrespective of the diver magazine test, if the risk benefit didn't balance everyone would be diving indies. The only failure that would lead to a complete loss of gas is if the valve broke, if you lose an o ring at one cylinder end (left post say) you can isolate the gas in the middle and then still have access to the gas in the right post. If both go your f****d without a paddle. But then what would be the flow rate out of the cylinder???

Or the isolator / manifold?

Originally Posted by Ferg3333

Also as for isolation, if you have the set configured correctly and once proficient you can shut down the freeflow in less than 10secs. Using both hands one on the isolator and one on the offending post. Then reopen the manifold and all is good. hopefully The problems come when you have to do the full drill and once good this can be done in about 30-45 secs I reckon. I never timed myself when I was on OC.

I agree and think the key here is practice. It's probably very very rare to have to shutdown... but essential that you can if you're manifolded.




Just being Devil's advocate really... I felt that manifolded was the right choice for me and my style of diving and switched from indies to mani's.

S