Pony Bottles

Bending the rules diving has a lot in common with speeding - do it every journey and you'll be sure get a ticket. But once in a while, we usually get out of the car smiling...

50%, IMO, is far too rich for bail out. I find it difficult to go into deco if I'm breathing 36% at depth from a single 12 x 300. And the difference between 36% and 50% in deco obligations is not worth bothering about...

If I need more back gas and acquiring deco, then I'm carrying 2 x 12's or 2 x 15's and then I'll have some proper deco mixes on board.

But hey, we're meant to be talking about ponies here...

1. Spare Air is neither use nor ornament

2. A 3 litre pony rocks, and it really dosn't matter what you fill it with (21% or lean EAN).

I would like to do some solo diving this summer...should I just stay shallow....

I think that this is by far the best policy for solo diving. Stay <10m and then your SpareAir source is fine for these conditions as a few breaths and no safety stop are all that are required to get to the top. This is usually the best area for photography anyway.

I'm at the instructor level, but not a technical diver...

For 25 metres plus ...

25m plus solo - yeh gods - If you are planning to go solo and deep you definitely should have full redundancy. Get a technical course. I would advise the TDI SoloDiver Course. This has been discussed on other threads here and here at Wetpixel.

Cheers

Hal

SpareAir is better than no air but...

 

In a perfect world I'd be diving a small set of doubles with isolated manifolds using 32% and running my computer on air settings.

 

Unfortunately, that isn't possible most places I dive so basically more air is better air.

If 3CuFt helps you stay alive then OK but as has been mentioned earlier this is a pretty contentious issue.

 

Here is a question for you: do you know your max 02 consumption rate at the surface?

 

Here is what I know about mine (mind you this is absolutely Max)

Feel free to correct my calcs since I did them in a hurry

 

If my heart rate is topped out my Max 02 consumption is 46.8 ml/Kg/min

Now I weigh 70Kg so at 32% mix 1 CuFt will last me about 25 seconds

So, the 3CuFt tank would last me all of one minute.

Now, hopefully I'm not maxed out heartrate wise, but one must also then account for the consumption rate at depth.

 

Trust me, if you do run out of air at depth, your heart rate will most probably skyrocket and so will your breathing rate.

Sorry, but I must be missing something?

46.8 x 70 = 3276ml / min or 3.276 L/min.

1cf is roughly equal to 27L and 32% of 3cf is ~ 1cf so there is roughly 27L of O2 in the spare air.

27L /3.276L/min is ~ 8 minutes.

Of course you would also have to account for the fact that we are very inefficient at extracting O2 from the air we breath and without that part of the equation the argument is meaningless unless you're on a rebreather.

Cheers,

Mike

Recreational divers, and even technical divers, seem to get themselves into trouble by taking a shortcut when it comes to redundancy - for example, there are multiple incidents of divers using a single and taking along a slung cylinder as their "redundant gas supply". Hence to get into trouble.

I would submit that if you are feeling the need for redundancy, then it should be real redundancy in the form of manifolded doubles - something that you can save your life with.

All the best, James

I would submit that if you are feeling the need for redundancy, then it should be real redundancy in the form of manifolded doubles - something that you can save your life with.

"Here, here", *clap*, *applaud*

Cheers

Hal

25m plus solo - yeh gods - If you are planning to go solo and deep you definitely should have full redundancy. Get a technical course.

SDI Solo, TDI everything and PSA Advanced Trimix... But you are absolutely right.

1cf is roughly equal to 27L

Damn that Metric system

I have a spare air and solo dive on occasion. I typically don't go deeper than about 60ft while diving solo and can do an emergency ascent from there with no help. Spare air will give me those few extra breaths to slow my ascent.

Big pony bottles are a pain. On a shore dive where you're hauling tanks, forget it. I haven't had to do an emergency ascent with the spare air but have practiced with it from 50ft. It is typically designed to get you 60 breaths at the surface. That varies per individual but you can do the math from there. At 33ft you get roughly 30. At 99 you get 15 etc.

Recreational divers, and even technical divers, seem to get themselves into trouble by taking a shortcut when it comes to redundancy - for example, there are multiple incidents of divers using a single and taking along a slung cylinder as their "redundant gas supply". Hence to get into trouble.

 

I would submit that if you are feeling the need for redundancy, then it should be real redundancy in the form of manifolded doubles - something that you can save your life with.

All the best, James

I think you have a good point, but it depends on the diver's perspective. I am a pretty conservative diver, seeing no real attraction in pushing the envelope. I often get disdainful looks because I wear a 'conservative' Suunto computer.

My goal in having redundancy is to help with some type of catastrophic failure like a first stage o-ring blowout at depth, or maybe helping another out of air diver without drawing from my main tank - rather than looking at it as something that allows me to suck my main tank dry.

MOST of the time I dive with a 12 + a 3 (both steel) and have got used to them now so that I don't even notice that I'm carrying a pony at all. I've never had to use the pony BUT a buddy has when his own regulator failed at 32m in very cold, fresh water (icing). Forget anything else - a 3 litre pony will deal with most (but not all) situations and in this incident we surfaced with plenty of air in reserve - I'd now consider a 3 litre pony as a pretty 'standard' bail-out. Anything smaller is potentially depth limited and is (imho) false economy. If you need anything bigger you are into something serious.

All that said, this only applies to me in the UK - elsewhere the logistics of hiring a pony set-up are generally an absolute pain in my experience!