Spare Air

[goonsquad]

Tell us what you really think Skim...

Next question is why do you read new posts on "old subjects"?

 

[friscuba]

Here's my experience. Back in the day when I was typically a 40'/50' for 40 minute diver , I pulled out my spare air on a safety stop and timed it, got around 2 and a half minutes. Nowadays I get twice that for bottom time, so getting a full safety stop in the unit if needed is no issue at all.

Many of the critics who are throwing out "math" to put down spare are are picking a 3-4 atm depth and treating it as though it's a constant. In reality you're either running out of air and grabbing your spare air and ascending, giving you varying rates of air consumption as you ascend, requiring lots more math to figure out how long it will last.... or you are trapped, at which you may only have a minute (using the 60' example earlier in the thread) on a 3cuft spare air, or 5 minutes on a 15cuft pony, to work youself out of trouble - in which case you could potentially be screwed no matter what size of alternate airsource you are using.

Spare air as a backup source to get you to the surface in the event you have unimpeded access to the surface when you run out of air at depth should do the job. At some depths if you are poor on air consumption you probably won't get a full safety stop in, but at least you should get to the surface assuming the path is clear.

In an ideal world, backup air sources are never needed, it's nice to have something though just in case.

 

[UCFKnightDiver]

Here's my experience. Back in the day when I was typically a 40'/50' for 40 minute diver , I pulled out my spare air on a safety stop and timed it, got around 2 and a half minutes. Nowadays I get twice that for bottom time, so getting a full safety stop in the unit if needed is no issue at all.

Many of the critics who are throwing out "math" to put down spare are are picking a 3-4 atm depth and treating it as though it's a constant. In reality you're either running out of air and grabbing your spare air and ascending, giving you varying rates of air consumption as you ascend, requiring lots more math to figure out how long it will last.... or you are trapped, at which you may only have a minute (using the 60' example earlier in the thread) on a 3cuft spare air, or 5 minutes on a 15cuft pony, to work youself out of trouble - in which case you could potentially be screwed no matter what size of alternate airsource you are using.

Spare air as a backup source to get you to the surface in the event you have unimpeded access to the surface when you run out of air at depth should do the job. At some depths if you are poor on air consumption you probably won't get a full safety stop in, but at least you should get to the surface assuming the path is clear.

In an ideal world, backup air sources are never needed, it's nice to have something though just in case.

It doesn't require that much more math actually but... assuming you are at your ndl and you run out of gas and ascend at the prescribed rate of 30 ft/min (wouldn't be great to just rush to the surface) At 60 ft(2.81 ATA)with the 3 or 6 cuft spare air:

So a minute at depth to figure out your problem, signal your buddy, get situated and start ascending you need 2.81 cuft of gas (remember you're stressed out 1 cuft SAC).

To go from 60ft to 15 ft a distance of 45 ft, which will take you 1:30. You need 3.18 cuft of gas.

For your 3 minute saftey stop you need 4.36 cuft of gas (5 cuft of gas or so to get to the surface).

So... you need 10.99 or 11 cuft of gas to get to the surface, assuming you follow the rules correctly. If using the 3cuft spare air you drown as well as the 6 cuft. Thus my comment that it's nothing more than a CESA aide.

Oh, and in an ideal world friscuba, people would plan their dives properly, and follow safe buddy practices, then I would agree backup air sources wouldn't be needed.

 

[knowone]

Pinto vs Granada

 

[Dr Wu]

I have performed the search and I have read peoples posts about the fact they hate it, but none of them seem to explain.

Here is a reason: Using a SA is slightly more difficult than using the search feature on a message board.

Folks who have difficulty with the later should avoid the former.

Simply put: It is simply to complex for some people.

 

[goonsquad]

Thanks Dr. Wu, but as I read through the posts (here and in the searched threads) all I find is anecdotal evidence and piss poor attitudes to back up the reasons people actually dislike SA.

Other people seem to see it as a tool with limited use. That I can completely accept. Piss poor attitudes toward something just comes across as piss poor attitude.

I'm not looking for an answer like "its great, go get one" to justify something. I was looking for a justified stance as to why a rec. diver not doing anything complex or overly deep would not benefit from having a limited use tool that could get them to the surface. I would think a case of the bends would be better than a case of the drowns...
Perhaps you're a dive god who will never have a problem or be separated from their dive buddy, but things happen. Sometimes you can plan a dive but not dive the plan.

Again, thanks for your insightful post.

 

[Dr Wu]

Thanks Dr. Wu, but as I read through the posts (here and in the searched threads) all I find is anecdotal evidence and piss poor attitudes to back up the reasons people actually dislike SA.

If you cannot find the answers you need either on the web or in the archives of this site there is something seriously wrong with you.

Perhaps you're a dive god who will never have a problem or be separated from their dive buddy, but things happen.

I cannot imagine the circumstances I would dive with a buddy.

 

[goonsquad]

Dr. Wu- I guess I rely on more than. "it sucks, it's too small to ascend from 150ft" type of nonsensical answers. Of course its too small, its not made for that. Nor do I rely on the positive reviews of its great, I used it in my pool.

I have read more than a few accounts of divers who have said it may have saved their lives during a OOA emergency, I have not found any accounts of a drown diver who had died clutching their SA, or even a diver found with a spare air missing from its holser, etc. (I imagine with the hatred some people have against SA, it would be posted on everyone of these types of threads)

Now please excuse me if I read articles in magazines like:
Spare Air Is Reverse Parachute of Scuba: Test Dive (With Video) - Popularmechanics.com
and give them a bit more credence than I give you.

Now if you're saying that a pony is better, I'd completely agree that in most cases it is. I myself would think though that using the right tool for the right job is a better strategy, if my dive plan is 30-60ft I don't really think lugging a pony around is the right tool...

According to almost every argument against SA, the exact same argument can be made against a pony. All I am hearing from people such as yourself is "have better gas management", okay, so tell me how do you manage an equipment failure at 60-100ft, without a redundant air supply?

Oh, again, thanks for your insightful posts...

 

[Dr Wu]

Dr. Wu- I guess I rely on more than. "it sucks, it's too small to ascend from 150ft" type of nonsensical answers. Of course its too small, its not made for that. Nor do I rely on the positive reviews of its great, I used it in my pool.

I have read more than a few accounts of divers who have said it may have saved their lives during a OOA emergency, I have not found any accounts of a drown diver who had died clutching their SA, or even a diver found with a spare air missing from its holser, etc. (I imagine with the hatred some people have against SA, it would be posted on everyone of these types of threads)

Now please excuse me if I read articles in magazines like:
Spare Air Is Reverse Parachute of Scuba: Test Dive (With Video) - Popularmechanics.com
and give them a bit more credence than I give you.

Now if you're saying that a pony is better, I'd completely agree that in most cases it is. I myself would think though that using the right tool for the right job is a better strategy, if my dive plan is 30-60ft I don't really think lugging a pony around is the right tool...

According to almost every argument against SA, the exact same argument can be made against a pony. All I am hearing from people such as yourself is "have better gas management", okay, so tell me how do you manage an equipment failure at 60-100ft, without a redundant air supply?

Oh, again, thanks for your insightful posts...

Do you really think you are the first person to show up on this board looking for detailed information on the Spare Air? Are you looking for some kind of credit for this unique degree of inquisitiveness?

The Spare Air has been discussed endlessly and in excruciating detail. All you have to do is read and learn.



As to the rest of your post..sorry but you even know the proper questions to ask. Vast ignorance is showing.

Just keep things basic for a while.

 

[JahJahwarrior]

According to almost every argument against SA, the exact same argument can be made against a pony. All I am hearing from people such as yourself is "have better gas management", okay, so tell me how do you manage an equipment failure at 60-100ft, without a redundant air supply?

Oh, again, thanks for your insightful posts...

Easy. Plan for gas failures. Figure out the rate that gas can escape via various failures, and use those numbers to figure out how long you can stay down before you have to turn for a "rock bottom" turn pressure.

If 6 cubic feet of gas is all you need to get safely to the surface from your dive, then use a Spare Air. If you need more than 6 cubic feet, use something bigger. It's really not any more difficult than that, and if you keep calling that answer "nonsensical" then I'm afraid that you probably face a long, tough life full of uncertainties.