Redundant System Geek?

[glbirch]

You have all that crap on one 1st stage, if you have a significant air loss failure of any second stage, you'll be SOL on all of them, since the IP will drop too low for any of them to work. This is one of those times where "something else to fail" can definately be a bummer. If it's true redundancy you're seeking, keep the primary and AirII as is, and put the octo on a pony. You could still share air and not use the pony. It would remain truely redundant to main tank failure.

Bit of a different mindset then. He'd be donating the primary and keeping the AirII.

 

[WarmWaterDiver]

Adder70, I like your perspective on doing the trigonometry in your head - maybe you could "patent" this as a new scuba "on-the-fly" technique and be the master instructor of this "new" dive skill.

 

[String]

Or just buy a wrist mounted backup depth gauge

 

[Scuba_Vixen]

Bit of a different mindset then. He'd be donating the primary and keeping the AirII.

Exactly, while the AirII isn't the greatest reg to have to use ... it is certainly adequate for recreational depths and not that hard to use with an ooa buddy. More importantly, if I have an ooa rec diver to bring up, I want them close enough that I can grab their bc strap and keep them where I can face them and control their ascent ... they are very likely to be near panic and unable to think or dump for themselves on the way up. Even worse, they may want to get to the surface asap without thinking of the consequences. Incident reports show that an ooa diver usually grabs the first thing he equates with air ... that's usually your primary with bubbles comming out while it's in your mouth. Expect that you'll be the one that ends up on the backup.

Darlene

 

[glbirch]

Exactly, while the AirII isn't the greatest reg to have to use ... it is certainly adequate for recreational depths and not that hard to use with an ooa buddy. More importantly, if I have an ooa rec diver to bring up, I want them close enough that I can grab their bc strap and keep them where I can face them and control their ascent ... they are very likely to be near panic and unable to think or dump for themselves on the way up. Even worse, they may want to get to the surface asap without thinking of the consequences. Incident reports show that an ooa diver usually grabs the first thing he equates with air ... that's usually your primary with bubbles comming out while it's in your mouth. Expect that you'll be the one that ends up on the backup.

Darlene

So, to picture this, I'd be hanging on to my (potentially panicked) dive buddy who's breathing off my primary, trying to control his bouyancy/ascent speed, while at the same time breathing off of my AirII on my BC hose, in coordination with dumping air through that same hose to control my bouyancy. Not exactly an ideal situation.

 

[Bretagne]

If my buddy had botha combo octo/inflator *and* safe second, I would certainly want to go over an air sharing procedure. I would also honestly wonder about the guy's decision making. What exact circumstance would require the use of three regulators on one tank, and what is the proper procedure for doing so?

My course director has such a gear, and has had to come beck to surface with two other people breathing on his bottle (I do not know exactly how they arrived to that).
Of course, his safe second is a full reg, 1st +second stage.

 

[ClassAction]

There is a growing feeling among experienced divers that if you feel you need a redundant gas system for safety, then you really need to be diving doubles, and not just a pony. I think there's 2 sides to that argument (specifically in the 80' to 130' range) .....
Darlene

Could someone explain why doubles would be more redundant than a pony? I understand that doubles obviously provide more gas, but why are doubles safer than a pony? That seems to be the prevailing wisdom on this board. From what little I know about doubles, don't you have to be able to quickly isolate the failure point in an OOA situation? Would this also require you to switch to another reg? It seems like there might be less to go wrong with a pony. Is this the case?

I'm a new diver and I'm interested in doing to wreck diving off of NJ this summer. Most boats require a pony or doubles. I know I'm a long way off doubles. Shouldn't I start thinking about a pony?

Thanks.

 

[matt_unique]

Could someone explain why doubles would be more redundant than a pony? I understand that doubles obviously provide more gas, but why are doubles safer than a pony? That seems to be the prevailing wisdom on this board. From what little I know about doubles, don't you have to be able to quickly isolate the failure point in an OOA situation? Would this also require you to switch to another reg? It seems like there might be less to go wrong with a pony. Is this the case?

I'm a new diver and I'm interested in doing to wreck diving off of NJ this summer. Most boats require a pony or doubles. I know I'm a long way off doubles. Shouldn't I start thinking about a pony?

Thanks.

If you subscribe to the virtues of diving with independant singles - doubles are not *much* more redundant than a single with a pony except for the volume of air which you mentioned. I use the word *much* above because with independant singles you would have your wing inflator off one tank and your drysuit (or backup wing) inflator on another tank. So you could have a tank fail but still have air and a means for power buoyancy.

If you subscribe to the notion of double tanks with a manifold and isolator - then doubles are a lot more redundant than a single with a pony because you can loose one "post" and with the isolator still have access to the air in both tanks.

--Matt

 

[ClassAction]

So in an OOA situation with doubles, you can shut down one reg and still access both tanks with the other reg? Is that what you mean by post? And if I understand you correctly, you might need to shut down the failing reg which is also set up to inflate your dry suit or wing... But I see what you're saying -- you still get access to the air in both tanks.

What special training is needed before using doubles? Would a novice ever use doubles? Thanks for the advice!

 

[Scuba_Vixen]

So, to picture this, I'd be hanging on to my (potentially panicked) dive buddy who's breathing off my primary, trying to control his bouyancy/ascent speed, while at the same time breathing off of my AirII on my BC hose, in coordination with dumping air through that same hose to control my bouyancy. Not exactly an ideal situation.

You haven't got the picture in focus yet .......

Plan A: They probably already snatched your primary out of your mouth ...
You hang onto his/her bc strap with with the left hand, you have your right hand to dump your and his bc by pulling the inflator hose (or a shoulder dump cord ... which ever is easier) .... on rec bc's, when in a heads up position, all ya gotta do is pull the damn* hose ..... it'll vent where the hose attatches (that's why it's called a "pull dump")..... You can maintain the most control in that way. Dealing with an ooa diver is never an ideal situation, ... but this way it's definately manageable ....

Plan B: .... The Usual Way it happens:
You give him your octo, (or he's grabbed your primary from your mouth and you have to grope for your octo), he's got it in a death grip, (he's scared sh*tless), .... he swims like h*ll for the surface, he's 3 feet above you, his bc is expanding, last thing on his mind is dumping air from it ... You're SOL and helplessly in tow behind. .... Not exactly an ideal situation ... as you say.

Obviously, if the other diver is only loa, or not in near panic mode, it wouldn't make a lot of difference if you gave them your primary or an octo, BUT, It's best to be prepared for the worst case. Don't become a second victim.

I'll go with Plan A: ..... Your choice is up to you ...

Hope that's a bit clearer,

Darlene