Choice of redundant air supply

Craig Campbell wrote:
> Should I go for an aluminium 3ltr pony to keep weight to a minimum to
> minimise imbalance, does anybody know what weight would be in a
> filled 3ltr aluminium pony?

Steel and Ali cylinders weigh about the same as it takes more Ali
to contain the pressure. I'd go for steel personally but others
may differ.

Either cylinder will make no significant differance to your
weight as empty they will be about neutral with the Ali slightly
more buoyant in the water so with regs and a gauge still less
than a kilo negative empty.

I like ponys. Yes, it is important not to think it is big because
if you pant you can get through it quickly but it contains as
much as the 50 bar reserve in a 12L and if you have another reg
to stuff in your mouth when something goes wrong you are less
likely to panic and suffer elevated breathing rates.

I hope you have a lot of fun together and never have to use it.

nigelH

Craig Campbell wrote:
> Should I go for an aluminium 3ltr pony to keep weight to a minimum to
> minimise imbalance, does anybody know what weight would be in a
> filled 3ltr aluminium pony?

Steel and Ali cylinders weigh about the same as it takes more Ali
to contain the pressure. I'd go for steel personally but others
may differ.

Either cylinder will make no significant differance to your
weight as empty they will be about neutral with the Ali slightly
more buoyant in the water so with regs and a gauge still less
than a kilo negative empty.

I like ponys. Yes, it is important not to think it is big because
if you pant you can get through it quickly but it contains as
much as the 50 bar reserve in a 12L and if you have another reg
to stuff in your mouth when something goes wrong you are less
likely to panic and suffer elevated breathing rates.

I hope you have a lot of fun together and never have to use it.

nigelH

Craig Campbell wrote:
> Should I go for an aluminium 3ltr pony to keep weight to a minimum to
> minimise imbalance, does anybody know what weight would be in a
> filled 3ltr aluminium pony?

Steel and Ali cylinders weigh about the same as it takes more Ali
to contain the pressure. I'd go for steel personally but others
may differ.

Either cylinder will make no significant differance to your
weight as empty they will be about neutral with the Ali slightly
more buoyant in the water so with regs and a gauge still less
than a kilo negative empty.

I like ponys. Yes, it is important not to think it is big because
if you pant you can get through it quickly but it contains as
much as the 50 bar reserve in a 12L and if you have another reg
to stuff in your mouth when something goes wrong you are less
likely to panic and suffer elevated breathing rates.

I hope you have a lot of fun together and never have to use it.

nigelH

Craig Campbell wrote:
> Should I go for an aluminium 3ltr pony to keep weight to a minimum to
> minimise imbalance, does anybody know what weight would be in a
> filled 3ltr aluminium pony?

Steel and Ali cylinders weigh about the same as it takes more Ali
to contain the pressure. I'd go for steel personally but others
may differ.

Either cylinder will make no significant differance to your
weight as empty they will be about neutral with the Ali slightly
more buoyant in the water so with regs and a gauge still less
than a kilo negative empty.

I like ponys. Yes, it is important not to think it is big because
if you pant you can get through it quickly but it contains as
much as the 50 bar reserve in a 12L and if you have another reg
to stuff in your mouth when something goes wrong you are less
likely to panic and suffer elevated breathing rates.

I hope you have a lot of fun together and never have to use it.

nigelH

In article <dcbc16$lqo$1@newsg2.svr.pol.co.uk>, Craig Campbell
<mail@craigcampbell.co.uk> writes
>I am new to diving and have just qualified as a ocean diver. I would like to
>have a redundant air supply instead of just an octopus.
>
>Opinions please on which to choose and for what reason;
>Pony, Spare Air or twinset? or just stick to buddy/octopus?
>
>I feel Spare Air appealing as no large tanks to cause imbalance or heavy
>twinsets?
>
>Look forward to some opinions

I think you'll get a lot of opinions against.

My quick calculation is that I dive with 12l and usually last around 45
minutes with 50 bar when I surface. The equivalent of using a 9l tank to
empty.

9l = 45 minutes
0.42l = 2.1 minutes

So I'd get 2 minutes worth of air at my average depth.


Someone else has done more calculations (based on the smaller 0.2l
version) at:

http://diveweb.oneandoneis2.com/spareair.htm

however they are flawed in one respect.

The bailout calculations give the maximum bailout until taking your last
breath. In reality what the spare air would mean is that you could bail
out from 20m and it would be empty, for example, when you got to 5m. You
wouldn't suddenly drown the moment you sucked your last breath from the
canister. I'd don't know about you, but I would much rather run out of
air at 5m when the spare air emptied than at 20m without one.


I'd rather have one than not have one. But I haven't got one. And I'm
not likely to buy one either. So unless someone's giving them away....

--
David Mahon

In article <dcbc16$lqo$1@newsg2.svr.pol.co.uk>, Craig Campbell
<mail@craigcampbell.co.uk> writes
>I am new to diving and have just qualified as a ocean diver. I would like to
>have a redundant air supply instead of just an octopus.
>
>Opinions please on which to choose and for what reason;
>Pony, Spare Air or twinset? or just stick to buddy/octopus?
>
>I feel Spare Air appealing as no large tanks to cause imbalance or heavy
>twinsets?
>
>Look forward to some opinions

I think you'll get a lot of opinions against.

My quick calculation is that I dive with 12l and usually last around 45
minutes with 50 bar when I surface. The equivalent of using a 9l tank to
empty.

9l = 45 minutes
0.42l = 2.1 minutes

So I'd get 2 minutes worth of air at my average depth.


Someone else has done more calculations (based on the smaller 0.2l
version) at:

http://diveweb.oneandoneis2.com/spareair.htm

however they are flawed in one respect.

The bailout calculations give the maximum bailout until taking your last
breath. In reality what the spare air would mean is that you could bail
out from 20m and it would be empty, for example, when you got to 5m. You
wouldn't suddenly drown the moment you sucked your last breath from the
canister. I'd don't know about you, but I would much rather run out of
air at 5m when the spare air emptied than at 20m without one.


I'd rather have one than not have one. But I haven't got one. And I'm
not likely to buy one either. So unless someone's giving them away....

--
David Mahon

In article <dcbc16$lqo$1@newsg2.svr.pol.co.uk>, Craig Campbell
<mail@craigcampbell.co.uk> writes
>I am new to diving and have just qualified as a ocean diver. I would like to
>have a redundant air supply instead of just an octopus.
>
>Opinions please on which to choose and for what reason;
>Pony, Spare Air or twinset? or just stick to buddy/octopus?
>
>I feel Spare Air appealing as no large tanks to cause imbalance or heavy
>twinsets?
>
>Look forward to some opinions

I think you'll get a lot of opinions against.

My quick calculation is that I dive with 12l and usually last around 45
minutes with 50 bar when I surface. The equivalent of using a 9l tank to
empty.

9l = 45 minutes
0.42l = 2.1 minutes

So I'd get 2 minutes worth of air at my average depth.


Someone else has done more calculations (based on the smaller 0.2l
version) at:

http://diveweb.oneandoneis2.com/spareair.htm

however they are flawed in one respect.

The bailout calculations give the maximum bailout until taking your last
breath. In reality what the spare air would mean is that you could bail
out from 20m and it would be empty, for example, when you got to 5m. You
wouldn't suddenly drown the moment you sucked your last breath from the
canister. I'd don't know about you, but I would much rather run out of
air at 5m when the spare air emptied than at 20m without one.


I'd rather have one than not have one. But I haven't got one. And I'm
not likely to buy one either. So unless someone's giving them away....

--
David Mahon

In article <dcbc16$lqo$1@newsg2.svr.pol.co.uk>, Craig Campbell
<mail@craigcampbell.co.uk> writes
>I am new to diving and have just qualified as a ocean diver. I would like to
>have a redundant air supply instead of just an octopus.
>
>Opinions please on which to choose and for what reason;
>Pony, Spare Air or twinset? or just stick to buddy/octopus?
>
>I feel Spare Air appealing as no large tanks to cause imbalance or heavy
>twinsets?
>
>Look forward to some opinions

I think you'll get a lot of opinions against.

My quick calculation is that I dive with 12l and usually last around 45
minutes with 50 bar when I surface. The equivalent of using a 9l tank to
empty.

9l = 45 minutes
0.42l = 2.1 minutes

So I'd get 2 minutes worth of air at my average depth.


Someone else has done more calculations (based on the smaller 0.2l
version) at:

http://diveweb.oneandoneis2.com/spareair.htm

however they are flawed in one respect.

The bailout calculations give the maximum bailout until taking your last
breath. In reality what the spare air would mean is that you could bail
out from 20m and it would be empty, for example, when you got to 5m. You
wouldn't suddenly drown the moment you sucked your last breath from the
canister. I'd don't know about you, but I would much rather run out of
air at 5m when the spare air emptied than at 20m without one.


I'd rather have one than not have one. But I haven't got one. And I'm
not likely to buy one either. So unless someone's giving them away....

--
David Mahon

In article <dcbc16$lqo$1@newsg2.svr.pol.co.uk>, Craig Campbell
<mail@craigcampbell.co.uk> writes
>I am new to diving and have just qualified as a ocean diver. I would like to
>have a redundant air supply instead of just an octopus.
>
>Opinions please on which to choose and for what reason;
>Pony, Spare Air or twinset? or just stick to buddy/octopus?
>
>I feel Spare Air appealing as no large tanks to cause imbalance or heavy
>twinsets?
>
>Look forward to some opinions

I think you'll get a lot of opinions against.

My quick calculation is that I dive with 12l and usually last around 45
minutes with 50 bar when I surface. The equivalent of using a 9l tank to
empty.

9l = 45 minutes
0.42l = 2.1 minutes

So I'd get 2 minutes worth of air at my average depth.


Someone else has done more calculations (based on the smaller 0.2l
version) at:

http://diveweb.oneandoneis2.com/spareair.htm

however they are flawed in one respect.

The bailout calculations give the maximum bailout until taking your last
breath. In reality what the spare air would mean is that you could bail
out from 20m and it would be empty, for example, when you got to 5m. You
wouldn't suddenly drown the moment you sucked your last breath from the
canister. I'd don't know about you, but I would much rather run out of
air at 5m when the spare air emptied than at 20m without one.


I'd rather have one than not have one. But I haven't got one. And I'm
not likely to buy one either. So unless someone's giving them away....

--
David Mahon

In article <dcbc16$lqo$1@newsg2.svr.pol.co.uk>, Craig Campbell
<mail@craigcampbell.co.uk> writes
>I am new to diving and have just qualified as a ocean diver. I would like to
>have a redundant air supply instead of just an octopus.
>
>Opinions please on which to choose and for what reason;
>Pony, Spare Air or twinset? or just stick to buddy/octopus?
>
>I feel Spare Air appealing as no large tanks to cause imbalance or heavy
>twinsets?
>
>Look forward to some opinions

I think you'll get a lot of opinions against.

My quick calculation is that I dive with 12l and usually last around 45
minutes with 50 bar when I surface. The equivalent of using a 9l tank to
empty.

9l = 45 minutes
0.42l = 2.1 minutes

So I'd get 2 minutes worth of air at my average depth.


Someone else has done more calculations (based on the smaller 0.2l
version) at:

http://diveweb.oneandoneis2.com/spareair.htm

however they are flawed in one respect.

The bailout calculations give the maximum bailout until taking your last
breath. In reality what the spare air would mean is that you could bail
out from 20m and it would be empty, for example, when you got to 5m. You
wouldn't suddenly drown the moment you sucked your last breath from the
canister. I'd don't know about you, but I would much rather run out of
air at 5m when the spare air emptied than at 20m without one.


I'd rather have one than not have one. But I haven't got one. And I'm
not likely to buy one either. So unless someone's giving them away....

--
David Mahon