Inverted Twins; Pro's & Con's

[Steve S]

Originally Posted by Clare Gledhill

Just so as not to disappoint Steve...

You could never disappoint me

Originally Posted by Clare Gledhill

I have met an incredibly tiny number of divers who cannot with correctly set up kit and practice achieve a fast shut down of a twinset which is the right way up. If you are one of this rare group and are intent of going to twins then by all means invert.

However, be very careful to ensure that you really can't reach before you enter the world of custom hoses, poor routing in overheads, reduced buddy communication during failures, valve guards etc. You may be able to reach after all.

With respect Clare most divers aren't as driven as you so rather than changing suit, undersuit, harness adjustment etc and undertake kamikaze tantric yoga stretching, inverting would be a much more sensible and cheaper option for the masses

Custom hoses are not necessary unless you want to run the inflate over the shoulder, or if you are happy to use an adaptor an off the shelf reg hose will do it.
Poor routing in overheads? as I see it I could only be a cylinder length shorter than with your method, Di and I managed to share air quite a few times on our recent courses without missing that length.

The communication during shutdown is a valid point, no system is perfect...even yours but in the scheme of things how hard or time consuming is it to look at a persons ar*e then tell them what you have seen especially as the bubbler will more than likely have shut the isolator down first
The valve guards are a given [but still £1.5k cheaper than a new suit ] and as I have said many times there is no reason why a person should not 'choose' to invert even if they can shutdown conventionally other than for conformity.

Originally Posted by Clare Gledhill

Incidentally, identifying which post is bubbling by listening is far easier than it sounds although there are failures which can give false impressions due to routing (a LP hose failing would be one). Personally, this girl who could not reach her left post at all a while back has identified a slow leak on the first stage, shut it off, reseated the first stage and gased it back up again - much to the amusement of my buddy at the time

I doubt listening to a bubbling post would be of any use to me as I'm a tad deaf especially with my hood on.

Safe diving,
Steve

[ardhill]

Originally Posted by Clare Gledhill

poor routing in overheads,

Genuine unloaded question...
What do you mean by the above statement Clare?

Oh, and for those folk who think there can be a problem with a buddy seeing your valves when you dive inverts... Iwas diving at the weekend when a buddy with inverts had a very small leak from one of his first stages. I was able to see, it fin up to him, indicate here was a problem and asked him to stop, then I worked on the first stage. It was simple to do and gave us no problems sorting it.

[Clare Gledhill]

Originally Posted by ardhill

Genuine unloaded question...
What do you mean by the above statement Clare?

The best way to donate gas if you cannot swim side by side if for the person recieving gas to be in front. They are unlikely to swim too fast as they are tied to you via their only gas source and if the regulator does pop out of their mouth they can turn for assistance rather than have to try to chase you down.

I’ve had to gas share through restrictions which have been so long and tight that I’ve had to be a full body length behind the person I’m sharing gas with. A two meter long hose only just makes it from my valve – I’d need a longer hose to donate if inverted which would give me additional problems with stowing etc. on normal dives. I wouldn’t want to use a 3 meter hose on every dive (bearing in mind that inverted cylinders given other routing issues) but I do need to know that I can assist my buddy through restrictions should he/she run out of gas. A two metre hose works when cylinders are in the ‘normal’ position.

HTH

[ardhill]

Originally Posted by Clare Gledhill

A two metre hose works when cylinders are in the ‘normal’ position.

Ah, OK

I have 3m on my primary for that very reason
I have 1m, joined to a 2m. The join is at my head when you run the 1m hose up from the regs, so I still have the full 2m to donate to the person in front of me in a restriction. I have used it like this in a real restriction (wreck passageway) and it works just fine.

All my hoses are 'off the shelf' I didn't want to get custom length hoses, so I do have a join on that one.

[liamm]

On my set the primary (long ish hose) comes forward from my hip, around my neck ect. so in a gas sharing situation it would only have to pass from my backside. Now i have long legs but not quite 1.5m, but i suppose with fins included the recipients mouth might need to be 2m from my backside.
Following a conversation (cheers Ardhill) i'll probably change my primary from a 1.5 to a 2m but with this even in an extreme environment, that i wouldnt be ready for, i could gas share with a diver head to toe with me.

Re the bubbling 1st stage Paul, when i stripped the set down at home the O ring was pinched - thanks for the heads up.

[Mal Bridgeman]

Originally Posted by liamm

On my set the primary (long ish hose) comes forward from my hip, around my neck ect. so in a gas sharing situation it would only have to pass from my backside. Now i have long legs but not quite 1.5m, but i suppose with fins included the recipients mouth might need to be 2m from my backside.
Following a conversation (cheers Ardhill) i'll probably change my primary from a 1.5 to a 2m but with this even in an extreme environment, that i wouldnt be ready for, i could gas share with a diver head to toe with me.

Re the bubbling 1st stage Paul, when i stripped the set down at home the O ring was pinched - thanks for the heads up.

Liam,

The OOG diver would be in front in the scenario that Clare explained....if the OOG diver is behind then you could pull the reg out of their mouth and not realise it

The long hose needs to go from the OOG divers mouth, along their body, past their legs, past their fins, have a gap so they are not kicking you in the face, then reach to your first stage.

With conventional tanks 2m does this job .... but with inverts you need an extra metre.

HTH

Mal

[ardhill]

Originally Posted by Mal Bridgeman

... but with uprights you need an extra metre.

Ahh, so you think that the valves should be at the bottom too

[liamm]

Ah much clearer now, i have plenty of skills work to do before i get myself into that situation and i suspect that i would struggle my my current kit set up.

i thought that having the hose free at my hip was an advantage - but it isnt really.

[Mal Bridgeman]

Originally Posted by ardhill

Ahh, so you think that the valves should be at the bottom too

Thanks .....Duly changed

[Steve S]

Originally Posted by Clare Gledhill

(bearing in mind that inverted cylinders given other routing issues) but I do need to know that I can assist my buddy through restrictions should he/she run out of gas. A two metre hose works when cylinders are in the ‘normal’ position.

HTH

As you said earlier, choice is down to the requirements for the type of diving we do, I have no interest in caves and with a buddy I would not be squeezing into such tight spaces in wrecks where I could not share air side by side so your scenario is not applicable to me.

Now a loaded question what other routing issues?

Safe diving,
Steve