Spare air/pony bottle---should I get one?

[Aanderson81]

That will vary dramatically according to the individual, especially when you consider that they are a bit stressed, so they may consume more air faster. Hence my recommendation to test in ideal conditions and understand that when the fan gets hit, they have less time.

I did an experiment where I timed how long it would take me to take 10 breaths at a rate that I likely would when ascending in such a manner. It took me 40 seconds. Now of course as one gets shallower, the amount of air molecules one breathes in decreases as they get closer to the surface. Let's say you have 20 breaths. For me, that is 80 seconds. 100' in 80 seconds. That's dangerously fast I would say. Risky for DCS. Personally, it was a pony bottle for me in the past (yes, I did haul one around, a PIA, but I'd rather have that than be dead). Today it is sidemount.

If I recall a CESA is generally regarded as 60 fpm so that would put you right around the mark for a CESA from 80 to 100'. Not ideal but as long as you are within NDL times you the risk should be manageable.

Is it idea for all circumstances? No. This is why I've personally moved on to a pony. But for warm water good vis group dives I think it's an idea tool that adds an extra safety level to the dive. It gives you an extra tool to work with that honestly you probably wouldn't otherwise have with a full pony setup because many would be tempted to leave it on shore for these dives.

 

[wetb4igetinthewater]

If I recall a CESA is generally regarded as 60 fpm so that would put you right around the mark for a CESA from 80 to 100'. Not ideal but as long as you are within NDL times you the risk should be manageable.

Is it idea for all circumstances? No. This is why I've personally moved on to a pony. But for warm water good vis group dives I think it's an idea tool that adds an extra safety level to the dive. It gives you an extra tool to work with that honestly you probably wouldn't otherwise have with a full pony setup because many would be tempted to leave it on shore for these dives.

It is slowly becoming recognized that 60 fpm is too fast, especially when one is close to the surface. There is a good reason why training orgs like GUE teach 30 fpm at depth and 10 fpm at depth for even NDL dives.

You do understand that NDL times are essentially educated guesses, correct? There are many factors at play here.

If you don't dive with redundant air, you better stay close to your buddy. Spare Air does not qualify as such.

 

[redacted]

Spare air is better than no air.

 

[Captain Swoop]

A Spare Air is a waste of money in my opinion.

It's a half hearted attempt at redundancy and gives a false sense of security.

Over $300 dollars? You can buy real redundancy for that.

 

[redacted]

If you have the room to pack it, a proper pony will allow a normal safe ascent rather than aqn aided CESA.

 

[TMHeimer]

I have a 13cf pony and rarely use it--perhaps if below 80' and/or with an instabuddy. Not sure why I picked 80'. I was told in the Deep course that you should use one on a "deep" dive.
I've never had Spare Air and have no opinion other than agree that it's obviously better than no air. All depends on type of diving & depths, I guess. Solo diving to 30' I don't take the pony as CESA is easily doable. Below that I start to think about it.

 

[DogDiver]

Wouldn't it be easier to keep track of your SPG and not bother with either a spare air or pony.
Been diving for 51 years and have never run out of air, nor the buddy I was diving with.

 

[Captain Swoop]

All the years I have spent sailing and I never fell overboard but I still wear a life jacket.
Do you have any secondary?

 

[redacted]

Wouldn't it be easier to keep track of your SPG and not bother with either a spare air or pony.
Been diving for 51 years and have never run out of air, nor the buddy I was diving with.

That works great MOST of the time. I guess some folks just want something that works all the time. Plus there are some ops that require a redundant air source if you want tyo dive solo.

 

[uncfnp]

Traveling with a tank is a Pita and the larger the tank the greater the pain but it can be done. We travel with a 13 when we fly to any warm water destination where solo (read no buddy) is likely to happen. For us this is most commomly Bonaire. Renting is often an option and sometimes they have tanks small then 40 available but relying on this does add uncertainty and you need to confirm availablity, cost and fills before travel. You my need to rig to sling and or bring a re set. We have rented ponies in Bonaire and Grand Cayman. If experienced, healthy and relative shallow diving, CESA may be a viable option.

For same ocean buddies, that is a tough call and I have very little experiece with it but I think I personally would treat it the same as I do solo if the depth is greater then about 40 feet. A slung pony, bought or rented is a good option. But a Spare Air in this case may be viable. On my recent trip to Cozumel I saw a fellow diver on the boat with one. It was very compact and the crew just whipped it full on the boat with a tank and he was good to go the rest of the week. Not ideal but in this instance I think you are more likely to carry it with you when you travel and dive.