twin Independants

[onwardsupwards]

How many of you guys/gals out there using twin independants can reach your left post to isolate, in the case of a failure.

C,mon truthfull now      (or right post for that matter) 

[Ian T]

Rick,

Hmmm, this old chestnut raised it's head on the Pen course again then huh. Interesting indeed. I might have a discussion this weekend about this issue. I don't see the need to be able to reach it to close it. You're on independents so you have already made the decision that you dont wish to access all your gas. Shutting the post down would only prevent the massive amount of air venting, dislodging silt. You could try breathing it til it ran out, though it wouldn't take long to empty the tank. I'm sure that in this situation, your buddy could swim over and shut off the post for you quite easily, upon noticing the issue.

Completely different story with side mounts though ( a form of twin independents, just differently configured ).

Using my teaching philosophy 'Understand the why ?', I just dont understand why divers need to be able to shutdown their left post. (Hmmm, I know a certain Pen instructor who dives Twin Independents, whose argument for not diving a manifold is that he has shoulder problems and cant reach his valves. Sure a shower of sh*t that he wouldn't be able to shut down his left post if it catastrophically failed.)

Ian

[Craig]

Right post - yep (eventually!)
Left post - no chance with my kit on

Note the new pen course contains a requirement that an indy diver be able to shut off at least RH post. This came out a few weeks before our course leading to some hasty practice!

Interestingly once I demonstrated this in Gouldens I was not asked to do it again nor was I hassled about flow checks before/after restrictions nor was I tapped for a reg change at any time during the entire course.

[JD]

As IT said, why? If you lose all your gas in 1 tank, it will only save you filling it, as you do not have access to it.
As for reaching the RH post yes, LH post no. Again though, WGAF?

The reason you need to with a manifold is you will lose ALL your gas. The worst that can happen is 1 tank on independents, ie half your gas. Is this a benefit?

JD

PS: Probably a more important issue, is it independents or independants?

[Ian T]

Craig,
Interesting point about not being asked to access your valves again for duration of the course...

You shouldn't be asked to do a 'flow check' with independents, there is no risk of left post roll off, as your left post is on the inside and valve orientation means it cant roll-off. You should be asked to switch regs though, this verifies that at the worst possible moment, you can access your emergency gas, even if in restriction, zero viz, etc. It also means that you actually check that the reg is still where you want it to be, clipped off and hasn't pulled out trailing behind you like some form of underwater air to air refuelling drone, which would be pretty darn useless to you.

Shutting down a LH post seems like a completely useless idea to me for a diver with independents, except to prevent silting from the venting gas. Hmmm, another of WMcD's weird teachings and ideas, that haven't thought the idea through to completion, without asking 'Why?', and hence considering if the skill is required.

What is more important in the situation of a catastrophic LH post fail, exiting the cave at the same speed as you entered ( since now down to half gas supply left to exit before needing gas from buddy ), or remaining in the cave for a few minutes, and trying to turn off the valve, which is only going to run out in a few minutes anyway if a bad enough leak (or reg free flow). If you did this, you would have just wasted time that you need to spend exiting the cave than stuffing around trying to do this.

thoughts ?

[onwardsupwards]

Reasoning pretty much as I imagined. I can see why solo divers may prefer independants ie little (not no) chance of losing all gas. Seems that the instructors recognize the the fact that shutting down the post is not that important for TIDivers, hence valve  shutdowns not pushed for Indies divers on course. 

[Ian T]

RN,

I think side mounts would be a very different scenario, as you have direct access to the valve, you could potentially turn the valve on, breathe, turn valve off, turn valve on, breathe, turn valve off. This could be done if in a real spot of bother, where you need the gas. Obviously not possible for Twin Independent Back mount divers.

The above is my reasoning for why I dont believe a LH independent valve needs to be shut down, or for access to valves by Twin Independent divers. Question on this however : Has the instructor and diver verified that BOTH cylinders are turned on ? (breathed off both regs while watching SPG). If not, access to valves would be required.

Cheers
IT

[JD]

Or access to BUDDY to turn them on for you!

JD

[PMH]

Indies are dangerous in caves and manifolds should be manditory!!!!!!!!!!

period

H

[JD]

The only time I have ever had a problem with a buddies tanks was in Easts, where my buddy had rolled off his left post, on his 55's no less..... So far, of the failures I have witnessed, it is manifolds 100%, independents 0%

Manifolds are dangerous and should be banned, except for deep diving. The fact people say Indies are 'Task Loading' is the funniest! Changing regs is hard? Ha hahahahahaaaaaa!!!!!!!!!!!!!!!!!

You guys should just buy a CCR 'breather each and be done with it, no more arguement.

JD

[PMH]

The only time I have ever had a problem with a buddies tanks was in Easts, where my buddy had rolled off his left post, on his 55's no less..... So far, of the failures I have witnessed, it is manifolds 100%, independents 0%

Manifolds are dangerous and should be banned, except for deep diving. The fact people say Indies are 'Task Loading' is the funniest! Changing regs is hard? Ha hahahahahaaaaaa!!!!!!!!!!!!!!!!!

You guys should just buy a CCR 'breather each and be done with it, no more arguement.

JD

you will never be GUE with an attitude like that

[JD]

Neither will you, but at least I could if I wanted to!

JD

[PMH]

Neither will you, but at least I could if I wanted too!

JD

I could if I wanted too!!!!!!!!!