Independent Doubles!

[HowardE]

Here's an idea then... instead of trying to "learn" how to dive doubles on the internet why not go out and find an instructor and get in the water with them and dive and.... dare I say it, actually LEARN.

Are you saying that the only way to LEARN is with an instructor?

 

[HowardE]

Haha no worries, I've never dove independent doubles or been around anyone that has but I know what has worked for me so far

A closed mind is a wonderful thing to waste.

 

[AndyNZ]

Good point. I dive solo but I don't always know if anyone else in the area might also be diving. I figure if someone sees me and happens to go OOA I want to be able to respond. It is the same reason I have a longhose. From a solo perspective I don't need it either.

To be honest, it seems a strange mid-ground to me!

Most people are trained to really only plan for one failure, which personally I believe is a little naive.

There would be a major issue in mixing a team of independent and manifold tanks in some situations where the independent diver suffers a left post failure, then the manifolded diver is OOG (for whatever reason). You are suddenly left with an awfully small reserve in just one cylinder for two divers.

I would assume that in the situation, two divers using independents would "go it alone", each with their own reserve?

 

[StreetDoctor]

So far I have not read many post from divers who have actual dove independent back mounted doubles, just a lot of crap from people who think they know how and what the problems can be. I also see a lot of real deep diving (below 200') and cave bias which was not done much at all with independent 72's or 80's.

Leaving the side mount guys out of this as they have it figured out, even if they don’t know it, I’ll go into a major factor with any back mounted independent system that none of you seem to have figured out.

All of you have talked about gas management, but when I started in the 80’s we never saw divers dead from gas management, we saw then dead from 2nd stage and gauge management issues.
Regulator and Gauge Management

It is imperative that you can tell which tank you are on by touch. That means that you can tell which 2nd stage goes with which gauge, quickly and easily.

In the 80’s it was very common to see independent 80’s and a pony on a diver doing deep dives to 200-250 feet. That meant that you would have 2 or 3 2nd stage regs around your neck. If they were all the same shape, it got hard to tell what tank you were on and how much air you had in that tank. More then a few divers were found dead on the bottom with full back tanks and an empty pony. What they did was mistake their pony reg for one of the back tank regs, got to the bottom, ran out the pony and panicked. Remember, this was the bad old deep air days as that was all we had, getting narcked was always a factor.

How many divers worked around this problem was to use Poseidon regs (one cyklon AKA Thor or the Hockey Puck and a Jetstream AKA Odin or a Shower Head) on the back tanks and a more standard 2nd stage like a USD Conshelf on the pony. These 3 2nd stage shapes are very easy to tell apart by feel.

Off of one of the back regs was a single gauge and off the other was a gauge/depth gauge console. The pony did not have a gauge. Many times the 2nd stage hoses and 2 gauge hoses were duct taped together to keep it all manageable.

The side mount guys never have this problem as the tanks and regs are by the distance of your body separate and confusion of which tank you have etc. is very hard to do.

Independent doubles are just one tool in the tool box, any particular diver may not use that tool, but it can be in your box if at any time you need it.

What exactly is the difference between gas management and gauge management? everything you posted sounds kinda like it's covered under "gas management"

 

[StreetDoctor]

A closed mind is a wonderful thing to waste.

If it's not broken don't fix it.

 

[StreetDoctor]

Are you saying that the only way to LEARN is with an instructor?

<insert sarcasm>
Yes! That's exactly what I'm saying

 

[DaleC]

To be honest, it seems a strange mid-ground to me!

Most people are trained to really only plan for one failure, which personally I believe is a little naive.

There would be a major issue in mixing a team of independent and manifold tanks in some situations where the independent diver suffers a left post failure, then the manifolded diver is OOG (for whatever reason). You are suddenly left with an awfully small reserve in just one cylinder for two divers.

I would assume that in the situation, two divers using independents would "go it alone", each with their own reserve?

I am trying to think how this would be different for two manifold divers.

If I have a left post failure I lose my bungied reg (as does a MD diver). I then switch to my longhose. At that point I/we are on the way up/out. My MD partner would have to be burning through gas about twice as fast as me to go OOG (serious gas planning error) and a ID partner would have to incur two failures to go OOG at the same time (3 failures if you count mine).

If somehow my MD partner goes OOG we would be forced to buddy breath I suppose but then again so would two MD divers unless one can shut down the left post and still breath off the reg. I don't think 1000psi is too small for two divers who are already ascending (remembering the dives I am describing). I know some MD divers who get close to the end of a dive with far less than that in reserve (especially on a second dive with the same doubles). The reserves are not set in stone either. If I go shallow I allow less, if I go deeper I add more. If the dive has a ceiling (real or artificial) larger tanks than Al80's could be used or at a certain point manifolds. I have no problem using the right tool for the job and I'm certainly not married to ID's. They just work well for the dives I currently do.


I have to admit I only plan for one failure for dives that have no ceiling. I don't know of anyone who reasonably plans for more (MD or ID).

Here's an interesting twist though.
When I ask MD divers why they choose to dive blind should they have a failure that causes the isolator to be closed and they have to breath the right post (no SPG) I am given the answer "it doesn't matter, either one has enough gas to get out or one doesn't." Seems like not too much concern about gas reserves there. What if their buddy goes OOG and they both have to breath off that reg? Would one rather be able to know how much gas is left or not.

 

[Sas]

If it's not broken don't fix it.

There are always ways to improve on things but if one never tries new things they will never improve.

 

[Gombessa]

There are always ways to improve on things but if one never tries new things they will never improve.

It's also a question of risk/reward. If I never buy a lottery ticket, I have zero chance of winning the jackpot; but at 1:40,000,000+ odds, I'll save that lowly US dollar for something else

 

[Sas]

It's also a question of risk/reward. If I never buy a lottery ticket, I have zero chance of winning the jackpot; but at 1:40,000,000+ odds, I'll save that lowly US dollar for something else

Sorry, don't think that is a good analogue. There is no risk to trying out different bits of scuba gear and seeing what one likes (within reason and if you are borrowing it, which is what most people I know do before forking out cash) other than the risk of having an uncomfortable dive now and again. Not like playing the lotto, which is basically a tax on the stupid.

I play around with different gear as much as I can. Sometimes I've had some horribly uncomfortable dives due to some bad setup I've dived with, but overall my changes to my gear as a result of experimenting has improved my comfort when diving a great deal.