Spare Air- good for diving or not?

[Vegan Shark]

Your dip tube clogs up ... WTF???? From what, your lunch? Go and buy more spare air, you really are going to need it.

I believe Dr. Bill had a tank clog up on him at depth years ago, resulting in a sudden lack of air, followed by an emergency ascent. Of course, doubles/a pony is the answer to these highly unlikely failures, not a spare air. But for vacation divers, a spare air is a lot more appealing than a reg + a pony + learning how to sling it.

 

[ajduplessis]

Must have been his lunch then ......

 

[Namreg 58]

Where would you attach a spare air in a DIR setup assuming right hip has canister, left hip has D-ring and knife?

Reminds me of a caricature of a CF diver with the Spare Air held firmly in place by his sphincter which was the only available space left.


Surely, one would have no need for a Spare Air as you would be running a gauntlet of DIR types, all eager to fulfill that "once in a lifetime" opportunity to donate their long hose to someone.

---------- Post added December 3rd, 2014 at 04:27 AM ----------

Your dip tube clogs up ... WTF????

Correct, the idea of a dip tube is to prevent clogging or liquid from entering when the tank is inverted. However I once saw a clogged tank valve where the dip tube was misssing and the tank had around a tablespoon of AC in it which had obviously come from a badly repacked or ruptured filter..........some compressor owners aren't as meticulous as one would hope so a regular visual is a good idea especially if the tank is filled at various locations.

Getting back to the Spare Air issue, what's with the myopic obsession by so many that a Spare Air or pony "MUST BE USED TO HEAD FOR THE SURFACE" or weren't they taught to think outside the square because it might kill you????

 

[DeepSeaExplorer]

ORRRRRRRRRRRRRRRRRRRRR!!! You could just watch your gas and never put yourself in that kind of situation. Follow the rule of 1/3's and you should never have a problem. 1/3 in 1/3 out 1/3 reserve for emergency. Plan your dive and dive your plan!

I agree that the best solution is not to run out of air in the first place, but you are misapplying the rule of thirds. It's not intended for basic open water diving. That would mean on a 30ft dive when an AL80 would last you an hour, you're limiting your dive to 20 minutes. Way too conservative and not very practical.

 

[diver 85]

Didn't answer poll cuz my choice was not there.......I've got ~ 2k dives & think SA is SOMEWHAT useful------ie if you get in OOA situation & a couple breaths might get you to your buddy( for BB'ing)---OR--if it could help you in a non-overhead ESA, to get to the surface......

EDIT:.I've had 2 in my life, got 1st one in latter 80's & it finally 'broke'---'gave out'(larger version) then someone gave me (my) 2nd one---smaller version that's still sitting(never used) on one of my diving shelves..

 

[Tigerman]

If your burst disc fails or your valve o-ring fails (the thing that seals the valve to the tank) it doesn't result in a free flow, it results in a jettisoning of air into the surrounding water at a very high rate
(you might get a minute if you're at the start of your dive). And depending on the failure of the 1st stage, same thing.
...

In my experience (yeah, my buddy actually did have a blown yoke valve o-ring at depth) you'll have a couple of minutes, not one.. and the regulator will be breathable unless you shut it down. It'll also be noisy...


EDIT: Oh, and no - nobody was going afterwards "wish we had a spare air with us"...

 

[boulderjohn]

In my experience (yeah, my buddy actually did have a blown yoke valve o-ring at depth) you'll have a couple of minutes, not one.. and the regulator will be breathable unless you shut it down. It'll also be noisy...

My only experience with a blown O-ring was with a DM in Cozumel. An O-ring extruded, sending a massive shower of air into the water around him. He took his BCD off, shut off the air, took the regulator off the valve, put the O-ring back into place, and replaced the regulator onto the valve. During that time he did accept a breath of air from my alternate. After he put the BCD back on, he took a long look at his SPG before finally deciding he did not have enough air left to continue the dive, after which he went back to the surface to change tanks. I think that if he had decided instead to head directly to the surface after the problem developed, he would have made it.

 

[Tigerman]

We coulda made it to the surface, but due to the fact that we where in the blue with plenty of overhead boat traffic, we shared my tank back to the reef and surfaced in the relative safety there..

 

[agilis]

I agree that the best solution is not to run out of air in the first place, but you are misapplying the rule of thirds. It's not intended for basic open water diving. That would mean on a 30ft dive when an AL80 would last you an hour, you're limiting your dive to 20 minutes. Way too conservative and not very practical.

My arithmetic indicates that 1/3 out, 1/3 in and 1/3 in reserve provides a 40 minute dive, not a 20 minute dive. If one does not count the return trip as part of the dive, then neither should the trip out be counted. Following that logic, the dive time in the example cited would be about zero.

Most of my dives are not that linear, not a simple 'out/in' plan. Typically, I dive over or enter very near to a defined area where I will be fish watching and exploring. I consequently apply the rule of thirds to planned activities and the area involved, calculating a maximum expenditure of gas at 2/3 of the quantity available. This requires a comprehensive pre-dive plan, and contingency plans should circumstances change.

I usually dive on jetties and inlets, generally not deeper than 35 fsw, and frequently at night. I carry a spare air on these shallow solo dives, though I have not ever had to use it in the 30+ years I've owned it. Like the multiple (4) cutting instruments I carry in these fishing line infested areas, it's a small unobtrusive safety measure. I try to keep a sleek streamlined profile while diving. The knives, shears and cutting devices do get some use.

On deeper dives I use a 6cf pony, and also have never had to use it except to check that all is working properly. 6CF is adequate for me, since I imposed an 80 fsw depth limit on myself when I reached the age of 70. Perhaps I'm too careful, but I've been diving a long, long time, and I'm still here.

 

[boulderjohn]

The rule of thirds is appropriate for some dive situations, but not for most recreational dives. There are a number of ways to plan for appropriate gas reserves so that one will not run out of gas on a dive. You simply choose the one that is appropriate to your dive plan. I teach a distinctive specialty in dive planning that goes into those options and much, much more. It does not require a whole lot of training to plan the point at which your buddy team should be heading to the surface to ensure adequate gas reserves to cope with any emergency.