Redundancy

[RyanT]

Yep, I also like the 19 cf as a pony. It's easy to sling and provides a decent amount of gas.

 

[Odiver]

App

Just use 1 cu ft per min as your consumption rate, and you can easily see & quickly comprehend the following:

At the surface, 19 cu ft would last 19 mins.
At a depth of 33 ft, 19 cu ft would last 9 mins.
At a depth of 66 ft, 19 cu ft would last 6 mins.
At a depth of 99 ft, 19 cu ft would last 4 mins.

To ascend from 99 ft properly would take you 3 mins. This would consume about 6 cu ft of a 19 cu ft bottle. That also tells you that the smallest bottle you could effectively get to the surface with from 99 ft without stopping at 15 ft, would be a 6 cu ft bottle. However the smallest bottle that I would ever recommend for dives to 99 ft would be at least twice that volume.

With a 19 cu ft pony bottle, that would leave you with 13 cu ft with which to do a safety stop at 15 ft, after your ascent. You could wait 8 mins at 15 ft with that much gas, even at an elevated stressed 1 cu ft per min consumption rate. You should have plenty of extra air with a 19 cu ft bottle, although you do not have time to be delayed at 99 ft for whatever reason while using it either.

Most normal RMVs are in the 0.5 to 0.75 cu ft per minute range. But when something goes wrong, a stressed breathing rate of 1 cu ft per min in the examples above is a reasonable estimation. Plus it makes the calculations in US Imperial for a pony bottle contingency easier to figure and see. . .

re

 

[Odiver]

Great, great video.

 

[hroark2112]

When I dive with a pony I use a 19 as well, with the Zeagle pony tank straps. I always have the valve open on the pony, some disagree.

The biggest thing to remember about the pony is the forget about it when you're planning a dive. It doesn't exist.

I've never used it myself, but I have had someone else need the air on a dive. Glad it was there!

 

[Odiver]

Much appreciated advise.

 

[2airishuman]

Feel free to chime in and share your thoughts on a secondary air source.

There is, at this juncture, no consensus in the "dive community" regarding the use of redundant air for recreational dives. The situation is much the same for us now as it was for technical divers in the 1990s, where people were designing their own gear and style of diving around their own perceptions of risk and the attitudes of others around them. Now despite the complaints about GUE and the DIR folks generally being too structured everyone who carries a long hose does it the same way. Didn't used to be like that.

So we have these passionate discussions about the correct size bottle, how to carry it, how to plan a dive with it, whether to put air or nitrox in it, etc etc etc. I have a feeling those will all be settled questions 20 years from now.

I'm thinking about adding a 19 cu ft pony alongside my Faber steel 100 cu ft. Although I, too, believe in being safe, despite the added expense I see a pony as a smart investment.

Good for you. Know its limitations, and carry it in such a way that you won't confuse the reg for it with the ones for your primary gas supply, since there have been accidents resulting from that sort of thing.

 

[Blue Quaker]

You might want to think about slinging a 40 cu.ft. from day one. It gives you lots of spare air if you need it. It is easier to take on and off when climbing a ladder on a boat and less weight on your back when walking with gear. As my mentor was fond of saying "Gas is Time..." If a problem crops up a 40 will give you more gas/time to sort things out and still make a safe ascent and safety stop...just a thought.

 

[Redfoot]

Hello @Odiver

I am in St. Clair Shores..... Funny that we both just joined up here.

Where did you do your Certification? (if you don't mind me asking)

Have you found any other members in our area?

Thanks!

 

[Lorenzoid]

Your best redundant air supply is a good competent buddy. . . .

That is one school of thought, and it's the one I subscribe to. My buddy and I have an understanding that I am carrying my buddy's reserve gas, and my buddy is carrying mine. My buddy and I also practice out-of-gas drills. My buddy's reserve gas is kept nice and safe in my tank, and I am ready and able to give my buddy HIS gas whenever he requests it, and vice versa. This way of doing things only works when there is a competent and reliable buddy pair who are on the same page. I don't dive solo or with unknown insta-buddies, but if I did, I might look into getting a pony tank.

 

[northernone]

To add another thought... in recreational depths my redundant air source is the surface. If ever I'm on a dive where I question if it's an easily viable option to have my next breath at 1atm I'm with a secondary airsource, buddy or bottle. Or a combination of both or multiplies of the second etc.