spare air

[FreedomPC]

I'm looking for a refillable backup air system that's small and easy to use. My fiance is a little nervous when we dive deeper than 50'. She told me that if she had something like this she would be more comfortable. I tried talking her into a pony but she wasn't having it . So it looks like I'm in the market for a spare air. Thanks.

[terrillja]

I'd read this:
Problems with Spare Air?

For about the same cost as a Spare Air, you can get a pony and reg with 30x the air.

[mentalmarine]

Cant help ya on the spare air, but I like your avatar! At least ya got your fiance in the water I am still working on mine.

[skdvr]

You should reconsider trying to talk her into the Pony. Have her get on here and do some reading and I really think she would go with a small pony. Even a little 13 cu ft woule be better than a spair air.

Just my opinion...

Phil

[frogman159]

Let say your using an AL80 filled to 3000psi (full)

Lets assume you dive to 60ft and this dive lasts you ~45 minutes when your tank hits 500psi

You used up about 66.67 cf of air in 45 min or 1.48cf/minute!

A spare air is 1.7cf and if you need to use it your likely stressed.

The point is I wouldn't expect that 1.7 cf spare air to last you more than 1 minute of stressed breathing.

Now factor in a deeper depth and the time your spare air will last will go down even further, If that doesn't convince her, its a waste of $200, not sure anything will..Get out the credit card

[mwhities]

Originally Posted by frogman159

Let say your using an AL80 filled to 3000psi (full)

Lets assume you dive to 60ft and this dive lasts you ~45 minutes when your tank hits 500psi

You used up about 66.67 cf of air in 45 min or 1.48cf/minute!

A spare air is 1.7cf and if you need to use it your likely stressed.

The point is I wouldn't expect that 1.7 cf spare air to last you more than 1 minute of stressed breathing.

Now factor in a deeper depth and the time your spare air will last will go down even further

I concur; very well said. If that doesn't change her mind, you better pack an al80 with a 40"+ hose for air share with her.

[FreedomPC]

Thanks for all the input. I forwarded all the messages to her. I think she is going to consider the pony with a 2nd reg. Of course when I suggested something like this she wouldn't hear it.

[No Misses]

If she is dead set against carrying a pony, get her the spare air.
I have a pony that I carry on deep dives or when I dive an AL80 instead of my HP120.
A pony does you little good if you are unwilling to carry it. If she will carry the spare air on every dive, it is better than a pony that she will not carry.
With all of that being said. I prefer the pony over a spare air. Spare air units come in 2 sizes 1.7 cf and 3 cf.

I have attached a spreadsheet that calculates your minutes of breathing gas at depth for different sized cylinders. All you do is enter your SAC, Pony size, & depth.

[FreedomPC]

Thankx. I read a previous message from you that had a basic chart. This is much better. I think she will carry the pony. She is more concerned about running out of air than having to carry something else. Her main concern was if she ran out of air started to panic and grabbed the octo instead of the pony reg. She said that if it didn't have a hose she would know it was the right one. Like I said she is still pretty nervous at this point.

[MSilvia]

Originally Posted by frogman159

Lets assume you dive to 60ft and this dive lasts you ~45 minutes when your tank hits 500psi.

A spare air is 1.7cf and if you need to use it your likely stressed.

Not that I'm advocating for the Spare Air (I'm not... I think it's ridiculous that they market them to divers), but in this particular scenario the diver still has 14.6 cubic feet of gas to get to the surface with. Out of air would be a totally different story but if you have 500 psi left in an 80 cubic foot tank, you aren't out of air yet. You can still get a lot of breathing out of an 80 cubic foot tank that's 16.7% full.

Just a nit pick, but don't go drowning with air on your back just because your backup ran out.