How to configure independent doubles

[dlarbale]

All,

Just a general question to see how people run the hoses on Independents. My current view - if your diving independents then your probably solo so why have a long hose. If your not diving solo then just have the one long hose and deal with an OOA in the normal manner but hand off the long hose.

OK I know there's an extra step in there for OOA to determine which hose is the long one but is this really a concern if your buddies are all diving independent config. Basically an OOA situation shouldn't be a rush affair as total air loss is not a possibility.

I don't want to start a debate about diving independent or not! I'm just curious about the different configs as I know a few people that dive 2 long hoses on independents (seems a bit overkill for the reasons stated above).

Thanks - Dave.

[andibk]

Dave,
I think you answered your own question. If you are diving solo there is no need for having a long hose. There is no sense carrying extra equipment that can add on to task loading or get tangled in something. When diving I make it a habbit of marking all of my regulators with either a tag or yellow tape. I either mark the tag/tape with the 02 percentage or B for bottom mix. As far as equipment configurations when I have a student I will teach him both ways of diving independents or with a isolation manifold. Let the student make up his own mind on what he feels comfortable with, he is the one who has to be comfortable in the water. There are so many positive and negatives with each one, you just have to weigh them out and use what you feel comfortable with.

Bruce

[Divesherpa]

If you plan on diving independents, I would recommend getting a big pack of flourescent zip ties. zip tie the SPG with the same color as the reg to avoid confusion. It really makes life easier.
No long hose needed if everyone is on indies.

[PeCeDiver]

Hi all,

I'm looking for a system to attach two regular "resort" tanks as independent doubles to my BC (Mares Synchro Power Tech). There is a set availabe from APValves, but apparently it can only be used with the "Buddy" BC series (http://www.apvalves.com/Prdtsfrmset.html). Is this true? Any recommendations on other "Twin Set Kits".

Thanks

[nickjb]

You can use the Buddy bands to join two tanks together then use an extra long cam band (or two depending on your BC) to go around the whole lot and join it to your BC

[PeCeDiver]

Nick,

so there are no bolts to attach the tanks to the BC? My BC has two holes that can be used to attach doubles. I'm not sure whether a setup with doubles attached to the BC via two cam bands is stable enough.

[Rick Murchison]

Here (http://www.dive-rite.com/products/gas/ind_dbl.htm)ye go.
Rick

[PeCeDiver]

Thanks Rick,

I'll check those out.

[O-ring]

What about taking a stage reg setup and some straps and rigging one of the resort tanks as a stage? I was thinking about doing that in Bonaire, but it wasn't worth the trouble.

[PeCeDiver]

I'd rather have the tanks on my back, because I want to have my arms completely free for my video camera.

I used a stage bottle in Bonaire while diving the Windjammer, but I found it rather clumsy.

[O-ring]

PeCeDiver once bubbled...
I'd rather have the tanks on my back, because I want to have my arms completely free for my video camera.

I used a stage bottle in Bonaire while diving the Windjammer, but I found it rather clumsy.
How is the jammer? Is it worth doing? Where'd you get the mix fills?

[PeCeDiver]

Nice topic, so we'll continue :D

The windjammer is a nice wreck and worth doing.

Mix ??? Not really needed for 21% O2.

I know it is not the best way, but we did it on air. Max depth was 60 metres (180 ft).

We followed a very conservative profile. From the reef to the Windjamer 12 minutes max, then staged deco starting at 24 metres. Total deco time was over 60 minutes (tables). The strange thing was that our computers showed less than 12 minutes deco.

[O-ring]

PeCeDiver once bubbled...
Nice topic, so we'll continue :D

The windjammer is a nice wreck and worth doing.
Nice...how intact is it? Any penetration?


Mix ??? Not really needed for 21% O2.
Uhh...no comment ;)


I know it is not the best way, but we did it on air. Max depth was 60 metres (180 ft).
Uhh...no comment ;) You may want to check out this thread for future reference (http://www.scubaboard.com/showthread.php?s=&threadid=21646) :D

[PeCeDiver]

We didn't try penetrating the wreck. Would have been too dangerous at that depth. But it is sort of intact. It lies on its side. There are also some humongous ankers. They can be found left of the wreck at 210 ft.

Have to go. I've got some work to do.

[rickw68]

Aqua Explorers, Inc. sells something called "Ultimate Velcro Double Bands".
http://www.aquaexplorers.com/double_bands.htm

I've used these a few times. You'll need a SPG on each regulator.
And you'll have to switch regs every 500psi or so, just to stay balanced. I actually breathed one of the tanks dry as I was doing a safety stop. If I was wearing a wetsuit, I would have had to orally inflate my BC at the surface.
Let me know if you are interested in a used set and I will check to see if I still have them.

Rick

[PeCeDiver]

Rick, I already ordered the Dive Rite system.

Thanks for the offer.

[beche de mer]

Anyone here dive independant (i.e. non-manifolded) doubles? If so, how is your gear configured?

[Rick Murchison]

Sidemount. (http://www.dive-rite.com/resource/sidmount/index.htm)
Rick

[beche de mer]

Rik - as a caver do you use independents simply because you can't manifold them in that configuration, or do you have a specific reason for wanting independent tanks?

[DA Aquamaster]

Side mounting results in a lower profile and helps cave divers slip through them little itty bitty cracks where sane people won't go. =) Given how the tanks are mounted on each side of the diver in that configuration, they cannot be manifolded. It is the accepted reason to use independent doubles

I also dive independent doubles but in more normal diving. I do it for the flexibility it allows. I can use independent doubles on a single tank dive profile, breathe from one tank and have what amounts to a 72 cu ft pony, or I can use them on double tank dive profiles managing the air in each tank by thirds and maintain full redundancy through out the dive.

They offer advantages for me in that I do not have to lug doubles around for fills and the family stock of tanks can be used by all members rather than having some reserved only for me when set up as manifolded doubles. It also has the advantage of allowing the same familiar configuiration no matter what the profile or when traveling and using rental tanks where doubles are not normally available.

Given that the water here is quite cold, the biggest threat in terms of a reg failure is a first stage freeze up. With a set of manifolded doubles some action is required to close the correct valve to preserve any air supply. With independent doubles, closing the valve with the free flowing reg is desireable but not absolutely required as with proper air management you will still have adequate air to ascend in the other tank.

Using independent doubles will grant you membership into a select minority group however as they are generally discouraged due to the undeniable need to manage your air correctly and the need to switch regs once or twice during the dive and the debatable assertion that the additional task loading resulting from those one or two switches is an issue.

It's not DIR but then neither is solo diving and that comprises about half my dives anyway. Independent doubles with an alternate air source on the "primary" tank such as an Air 2 is a very good set up for solo diving - but doubly controversial.

I use a set of Aqua Exlplorers Utlimate Velcro Double Bands. They work quite well are low profile and durable. They can also accomodate any diameter tank. They are more durable than most travel band arrangements and are less expensive than most at around $125. They work very well with a backplate but can also be adapted for use with a BC with a hardpack and holes for doubles.

[DA Aquamaster]

I should add that if you dive independent doubles it is a good idea to use or make your second stages visually and tactilely different.

I use a matching yellow hose protector where the LP hose attaches to the second stage and another one where the HP hose attaches to the SPG on the reg on the right tank and use nothing on the reg on the left tank. I always know what one I am breathing off and I know that the second stage in my mouth matches the SPG I am looking at. It avoids confusion at depth and reduces task loading.

I use a bolt snap attached to a fairly heavy o-ring around the base of the mouth piece. This keeps the not-in-use second stage clipped to a D-ring even after the most violent of entries and keeps things streamlined. But it still keeps it immediately available if you or your buddy need it right now and do not have time to unclip it. The SPG on the right is also attached with a bolt snap to a D-ring which keeps it out of the way but still visible.

I route both the second stage hoses over the right shoulder which facilitates switching and with a little practice you can remove, clip, unclip and insert the regs with one hand with only a very slight pause in yoru normal breathing cycle. It's not DIR but with proper attention to hose lenght it is very user freindly and very streamlined.

[MikeFerrara]

It sounds like a cluttered configuration to me. I can see it getting really complicated when wearing a couple decompression cylinders and a stage or two.

When you're not solo which reg do you donate?
Do you use a long hose?
How do you secure the reg you're not using?

[Tanto]

I've been using indipendent doubles for thirteen years now, configured as follows (seen from above a diver facing ahead):

1) left tank has valve knob at 10, three parallel hoses leave at 2, one is reg, one is SPG, one is drysuit inflation; if using dual bladded BC there's a fourth hose for it as second inflator is on the right.
2) right tank has valve knob at 2, three parallel hoses at 10, one is reg, one is LP BC inflator, one is SPG.
3) both regs are attached to the neck, SPGs are attached to a side D-ring, hoses to drysuit and inflators
4) hoses cross behind the head; no hose protrudes outside

Mostly dive solo, never with buddy, but if needed can donate either reg, no long hose.
I like it and I am very comfortable with it.

[DA Aquamaster]

MikeFerrara once bubbled...
It sounds like a cluttered configuration to me. I can see it getting really complicated when wearing a couple decompression cylinders and a stage or two.

It's not - you have the same number of LP hoses and stages you have with manifolded doubles. The only additional piece of kit is an extra SPG. The clutter isse is not an issue - anymore than it is anyway with stage or deco bottles.


When you're not solo which reg do you donate?

In the two air sharing situations I have been involved with in the real world, I used my alternate second stage as the primary was ripped out of my mouth by a diver in no mood to follow the normal air share signal ettiquette. So I plan on donating the primary.


Do you use a long hose?

I don't dive a long hose as there really is not a need for me to use one. I don't do caves and the limited wreck penetration I do engage in is normally solo. If someone is gonna screw up and silt out the interior of a wreck I want it to be me.

The argument could be made that a long hose allows you to get some distance from an out of air diver sharing your air via a long hose. However in my real world experience the out of air diver benefits psychologically from some close face to face eye contact and I like to maintain close contact with the diver so I can take the lead in the managing the ascent - especially if the other diver is panicky. I have no desire to get drug to the surface by my long hose. This is not normally an issue as they usually have a death grip on my left shoulder strap.

I realize it is un-DIR to dive with a buddy you are not real comfortable with and who may not have adequate skills, but I am in a situation where I dive with a lot of fairly new or inexperienced divers.

My normal buddy on non-solo dives is an instructor and the dive team training officer. Consequenlty I am usually along on the deep AOW training dives and most of the deep dive rescue team training dives to follow up the group and ensure there are no stragglers. If someone gets lost or has a problem I am usually the one who gets to assist. I can't say I always enjoy diving with some of these buddies and I trust almost none of them, but if we don't dive with them where exactly are they supposed to get the experience?

In a hard overhead tech situation with a reliable buddy a long hose makes sense if you need to exit in trail formation so if I dove in caves etc, I would reconfigure with a long hose. This is not a problem with independent doubles as the hose is routed the same way as it would be with manifolded doubles and can still be clipped off on a D-ring when not in use. In that situation you would also have the option of donating either the long or short hose, the only difference being the long hose may not neccesarily be the one in your mouth at the time.

Understand what I am saying here though...I am flexible enough in my configuration to adapt it to the situation. If I lived in Florida and did a lot of diving I would dig the three sets of bands and manifolds I own out of the closet and would have 3 sets of manifolded doubles. I am advocating that independent doubles work exceptonally well for me and type of diving I do and offers some advantage over manifolded doubles. I am not saying they are the end all answer for everybody else or for every diving situation.

I am also indirectly advocating for the right for each and every diver to make intelligent and informed decisions about their individual configuration. I feel that we will lose a lot as a community if we all adopt an agency approved cookie cutter approach to gear configuration.


How do you secure the reg you're not using?

It was covered before but I'll repeat it. The not-currently-in-use second stage is secured with a bolt snap attached via an O-ring arouns the base of the mouth piece. It can be clipped and unclipped to a D-ring in normal use and can be pulled free easily with a sharp tug in an emergeny when someone needs it right now.

I have a center pocket on the waist strap and have a D ring attached there. Both second stage hoses are just long enough to reach the D-ring and are clipped to it when not in use. The right side SPG also clips to this. There is no extra hose lenght to deal with and they lie flat against myu shoulder and down the front of my chest. It is very streamlined and there is no hose hanging out in space. It is actually more streamlined than having the alternate second stage dangling on a necklace.

If you prefer a surgical tube or bungee necklace could be used for both but I don't prefer to do this as my method involves less clutter and keeps the "short" hose closer to my body.

As Tanto points out, hose routing is very efficient particulary with some attention to proper hose lenghts.

[toodles]

Just thought I would throw this in....

Independants are the way to go.
I would agree that it takes a lot of discipline to dive this
way, however the benefits outweigh the negatives.

Sure, you are going to have to put up with more SPG.
Big Deal.
Would you rather dive with a isolation manifold and in the event of a first stage failure on your left post you would not know how much air you would have for the remaining portion of your dive?
I would choose NO.

The arguement that the hoses are not as streamlined is not a valid one either. I will admit that there are some first stages out there that do not have the best ports for hose routing but with proper research you will find certain ones.
I recommend the Apeks DS4 for independants.

On my left post I have on my first stage my BCD inflator hose, my SPG, and my 7 foot stuffed hose attached in front, along with my primary second stage.
On my right post I have my drysuit hose, my SPG, and my secondary second stage.
All hoses are practically pointed straight down from my first stage.
It is very clean.
I use a necklace to hold both my primary & secondary regs.
They are clearly marked along with my SPG'S to avoid mistakes.

My 7 foot hose is attached very streamlined near my left shoulder on top out of the way of any deco bottles.

I do not believe in donating my primary in an OOA emergency for several reasons. Having my 7 foot hose in the place where it is, an OOA diver can see it from not only from the front and side, BUT
also very accessible from behind also. (if I was diving with 7 foot primary in mouth and my buddy was behind and needed air fast, would he be wasting time to get your attention first?)

As far as gas is concerned, use the rule of thirds.
Yes you do have to moniter two SPG'S.
What's the big deal? Most of the time you will only do one switch on your back gas underwater.

Doesn't it seem odd that it's OK to do a gas switch to your deco
gas, but it's WAY TOO COMPLICATED to do a switch on your backgas?
Diving independants is very easy.
It's just a lot of people will not admit that they cannot do it very well so they preach that it is difficult or too much task loading.

To them I ask, IS IT REALLT THAT BAD?
Don't you switch a reg every time you switch to deco?
You did it as your FIRST skill in your OW class!

these are just a few things to think about.
I could go into a lot more but no time.

Just make sure no matter how you configure your gear,
Think safety for yourself FIRST (by the way I do not solo dive)
Then think how to streamline your gear and dive it SAFE.

I have seen alot of CLEAN configurations out there.
I have seen alot of bird's nest's also.

Lean toward a clean configuration but do not jeopordize safety,
and remember think for yourself and do not let anyone think FOR you.

Good luck

[DA Aquamaster]

Well cool...the number of independent doubles divers on this board has just doubled. Welcome to the minority. :D

[matt_unique]

I have my PADI Master Diver cert and I'm mid-way through the TDI Deco Procedures course. I consider myself a novice relative to some of the people I dive with.

I am doing my course with single 120's with an H or Y valve and a 30CF deco bottle. The other students in my class are on doubles with the manifold and I don't buy it. I don't like the idea of the back gas supply being linked such that one leak anywhere in the system can empty your entire supply. Of course through the valve drills you learn to isolate the leak. I asked the instructor, if you had a leak would you really be able to tell which side it was coming from underwater. He said you would know but I wonder how obvious it would really be. I prefer the idea of just switching regs just as I would with a deco or pony bottle. I also like the idea of having an SPG on every tank.

Has anyone experienced a leak? Was it obvious where it was and you were able to isolate the leak on the first attempt?

--Matt

[DA Aquamaster]

Matt...I share your concern about the need to close a valve with manifolded doubles. But not because the leak may be hard to find. With a freeflowing second stage it's easy to detemine what side needs to be shut off. With other minor leaks from leaky o-rings and burst discs it is potentially more difficult to locate but also less time critical. If you have to, you do what it takes to see the problem and then close the correct valve which may not actually stop the leak (leaky burst disc, neck o-ring etc).

I normally dive in very cold water and with high performance regs. The biggest risk I face is a frozen first stage which will result in a full open max effort free flow. I have had 2 in my diving career and the first one was with a MK 3 and took forever to dump the tank. The second occurred with a much higher performance Mk 15 first stage. Based on my previous experience and on the presence of a redundant air source, I did not get too excited but was then totally amazed at how fast it dumped the entire contents of a 72 cu ft tank at 140 ft. It was really impressive.

Had I been using manifolded doubles it would have arguably taken twice as long to lose all the air, but all the air would have been at risk if a timely effort was not successfully made to close the valve to the frozen reg or at least an isolator valve. Speed is quite literally life in that situation and it's a situation I prefer to avoid.

Consequently, my preference is to dive independent doubles as my entire air supply is never at risk from a single failure. It is a good idea to close the valve on the freeflowing reg as soon as possible as the valve can be turned back on and the remaining air accessed in a couple minutes after the ice thaws, but it is not absolutlely required as it would be anytime a manifold is involved.

In my case with predominantly deep cold water diving, the independent doubles configuration just makes the most sense to me. If the biggest risk of a failure was something else, I'd consider a different configuration.

[Tanto]

The issue of how fast a tank is emptied at depth is a very interesting one. I did some dry testing after a nitrox tank was emptied in a matter of seconds at 105 meters/344ft, then I discussed those results with an hydraulic engineer.
Depth increases substantially the emptying speed, and so does the reduction of density (i.e. using helium).
As crazy as it sounds, you can actually empty a 10/70 80cf stage at 330ft in about ten seconds, yes, 10 seconds, if the freeflowing regulator is a Jetstream, but it may take as long as 30 seconds or more with any el cheapo reg.
I know it sounds unbelievable, so for those of you as skeptical as I was, take an air filled (unless you enjoy dumping helium) 80cf tank in your garage, attach a Jetstream to it, open the DIN valve all the way and depress the membrane of the second stage and time how long it takes to empty the tank.
Then apply the laws of physics and determine what than would be with a 10/70 mix at 330 ft. Scary, isn't it?

One more reason to dive indipendent twins, as DAAquamaster suggested.

[DA Aquamaster]

I spent much of this year diving with a MK 20 D400 and MK 25 D400 on my tanks. I did not have any freeflows with either reg despite the questionable TIS kit but I was also never comfortable with the elevated risk of these regs in cold water compared to the virtual in freezability of a MK 10 with a properly maintained SPEC kit.

When I added the higher flow rate of the MK20/25 to the mix, I decided to go back to my Mk 10's as the MK 10 first stage has always demonstrated more than adequate gas delivery yet does not have the excessive and unnecessary (from a practical standpoint) flow rate of the Mk 20/25. The excessive flow rate increases the adibatic cooling load on the reg and further increases the air loss in a given amount of time in a free flow situation if the first stage does freeze.

So it is a technological step backward (about 20 years) but it is the right decision for my particular diving profiles and increases the margin of saftey both by reducing the potential of a freeflow and by minimizing the air loss without compromising the regulator performance needed at depth.

It's counter intuitive from a concrete linear thinking perspective, but faster or bigger is not always better and that reasoning makes perfect sense from a systems thinking perspective.

[Tanto]

I believe that the huge flow rate of the Jet is due to the second stage, as a simple comparison with the Cyklon will show (they share the first stage).
Anyway, flow rate and breathing effort are entirely different things, in most situations.
A fit, well trained and relaxed tech diver at 300 ft breathing hi helium mixes in the correct position (horizontal body, face partially tilted up) will probably breathe half cubic foot per minute * 10 atmospheres = 5 cubic foot per minute, any reg will provide that, cracking and inhaling efforts will be the only things he will notice, so any second stage with a good venturi and a good adjustment knob will do.
So in a "safety" perspective, DAA reasoning seems absolutely flawless to me.

[Manos]

I compare diving indep. doubles with driving a motorcycle on one wheel. Looks cool but at the end of the day is a suicide.

Manos
www.dir.cy.net

[MikeFerrara]

Manos once bubbled...
I compare diving indep. doubles with driving a motorcycle on one wheel. Looks cool but at the end of the day is a suicide.

Manos
www.dir.cy.net

While I dive manifolded doubles (probably for the same reasons you do) I don't think independant doubles, sidemount for instance, is suicide.

If I was going to dive independants I'd sidemount em. No sense in having to carry both at one or suffering the larger profile when they don't need to be straped together. A sidemount diver I know swears that your valves belong in your arm pits. LOL

[ew1usnr]

Two other adavantages of independent doubles are:
1. It makes unscrewing the valve for a VIP quick and easy.
2. It saves money because you don't have to buy a manifold.

[Duncan Price]

MikeFerrara once bubbled...


While I dive manifolded doubles (probably for the same reasons you do) I don't think independant doubles, sidemount for instance, is suicide.

If I was going to dive independants I'd sidemount em. No sense in having to carry both at one or suffering the larger profile when they don't need to be straped together. A sidemount diver I know swears that your valves belong in your arm pits. LOL

I think that being able to lose all your gas at once is suicide. With independents (sidemount or backmount) you can only dump half your gas. With a manifold you do have the potential to isolate a rogue regulator and still have access to all your gas (providing you've got some left). Furthermore you can share gas more easily - though with independents gas sharing is a last resort since you should still have one funtional set. I'd say its pretty evenly balanced between independents and manifolds for safety.

Arguments are made for increased task loading with independents but I say that its not the big deal that people make out. Many European cave divers employ independents (including quad rigs) because they can be broken down easily for transport.

I prefer sidemounts due to the lower profile and ease of reaching your valves. Besides, backmounts don't fit most of the places I go.

Duncan

[dvas]

Hi,
as a part of my ANDI tek certification (I am trimix certified), I was teached to dive independent tanks. The main point behind it to have two totally independent systems, and with using the 1/3 rule, there is always 1/3 of the whole gas available...
If you need more info, I'll be glad to provide.

Sasha

[toodles]

This is so great to hear.

Cheers to all on the board that have thought through the
advantages of diving independants.

I believe most divers do not dive independants because
they were told not to by their instructor or books.

It would appear that most have not been given ALL the
information with DIFFERENT scenarios.

I understand I am in the minority and others will dive differently,
however in my travels I have found that it seems more divers
dive independants in countries outside the USA.

Why?

[Duncan Price]

toodles once bubbled...
Why?

The dual outlet isolation manifold was invented in the US and its adoption has spread from there. As with any configuration, each has its merits and demerits. Often the favourable case it put for one option whereas only the drawbacks of the alternatives are promoted. I know of some (cave) divers who use a manifold but dive with the isolator closed (effectively independants) when they happen to be operating alone - sort of the "best" (?) of both worlds.

I would advise against mixing a team of divers using independants and manifolds.

Duncan

[ew1usnr]

toodles once bubbled...
I believe most divers do not dive independants because
they were told not to by their instructor or books.

I was REQUIRED to have a two-valve manifold in order to get my cave certification.

I also dive with side mounts and do not have any difficulty monitoring the air in two tanks. I watch the gauges of course, but the tanks themselves remind me to keep them even. If I don't they will float me sideways.

The manifold keeps things simpler because there is only one gauge to watch. But, I don't think that the manifold is more safe.

I don't sidemount all the time because back mounting lets me wear bigger tanks plus stage bottles.

[dennisgrimm]

Is ANDI the only agency that teaches how to dive either independants or manifold safely?

Does every other agency say "independats suck" and not explain why?

Of the people that trash independats, who has actually tried diving in this configuration for an extended period of time?

I am interested in hearing from people that have dove both for more than a couple of dives about their experiences.

I have heard from too many people that repeat what they have read without trying it themslefs. [To this someone could respond "I have read that jumping off a bridge is a bad idea, that does not mean I am going to try it." Don't tell me that. Diving independants a couple of times is not 99.98% certain to kill you.]

[MikeFerrara]

dennisgrimm,

To my knowledge the other major agencies (with the exception of GUE) achknowledge independants as a valid choice. Not all instructors will go that rout though.

[toodles]

Good question Dennis.

I wonder just how many divers have TRIED independants.

I have had converstaions with other divers whom have either been TOLD that they are dangerous or that they are wrong.
Then I have asked them if they have tried diving with them.

Usually the answer is NO.

[dennisgrimm]

I guess that ANDI is the only agency that teaches people how to dive independants?

How about cave courses?

Does anyone teach how to properly sidemount their tanks? I have seen a couple of websites, but that is it.

Am I THAT weird? :confused:

[MikeFerrara]

dennisgrimm once bubbled...
I guess that ANDI is the only agency that teaches people how to dive independants?

How about cave courses?

Does anyone teach how to properly sidemount their tanks? I have seen a couple of websites, but that is it.

Am I THAT weird? :confused:
As I said, I don't think any of the tech agencies accept GUE disallows independants. That doesn't mean any given instructor will teach it though.

NACD, NSS-CDS and IANTD all have sidemount cave classes. I'm sure other agencied do also. Of vourse the CDG but they're across the pong.

[MikeFerrara]

toodles once bubbled...
Good question Dennis.

I wonder just how many divers have TRIED independants.

I have had converstaions with other divers whom have either been TOLD that they are dangerous or that they are wrong.
Then I have asked them if they have tried diving with them.

Usually the answer is NO.

I don't know if you need to try them to have good reason to decide against them.

My former cave instructor does most of his own diving sidemount so it isn't like his students aren't exposed to it or are told that it's wrong. I have a sidemount rig but I'm not really using it at this time but I have. So I guess you could say I've tried independents.

The TDI tech material has info on independents but in my trimix class we dived with a manifold. I don't think I'd need an instructor to transition to independents if I decided to.

After you've been at it a while it doesn't matter so much what you were told. I think you'll make up your own mind.

[Tanto]

MikeFerrara once bubbled...


I don't know if you need to try them to have good reason to decide against them.



Perhaps not, but if you declare that task loading is an issue, you should at least have tried them for some time. Here in Europe most cave divers have always been diving indipendents and I've never ever heard that monitoring air and switching regs was an issue; simply, it is not.
Monitoring air and switching regs becomes quickly a second nature.

In my opinion in the US people is afraid it might be more difficult so they resist it. Equally, europeans are afraid of catastrophic loss of air, and resist manifolded doubles. JJ admits though that for solo diving indipendent twins might be a better option.

One very true thing pointed out by DAA was that you can always dive indipendents no matter where you are, just pair two tanks, so you have one diving style and one only and never have to change or adapt. And if you need to dive sidemount you're ready for it.

[coffeefein24]

Well cool...the number of independent doubles divers on this board has just doubled. Welcome to the minority. :D

You mean tripled. Just purchased the ultra twins dive rite setup from the LDS. plan on using it for my ice diving. Get that tank off my chest. Two SPG's, no big deal, I always check the other divers gauges during the dive anyway.

nh

[BigboyDan]

I first dove independent doubles in 1974; took two steel 72s, two Conshelfs, two SPGs, put them in a set of twin bands, and attached them to a backplate. Nobody told me how. I was 17 years-old. Swam across Lake Travis. Easy.

[Curt Bowen]

All,

Just a general question to see how people run the hoses on Independents. My current view - if your diving independents then your probably solo so why have a long hose. If your not diving solo then just have the one long hose and deal with an OOA in the normal manner but hand off the long hose.

OK I know there's an extra step in there for OOA to determine which hose is the long one but is this really a concern if your buddies are all diving independent config. Basically an OOA situation shouldn't be a rush affair as total air loss is not a possibility.

I don't want to start a debate about diving independent or not! I'm just curious about the different configs as I know a few people that dive 2 long hoses on independents (seems a bit overkill for the reasons stated above).

Thanks - Dave.


Try sidemount for independant doubles. Much safer than back mounted cylinders

[wedivebc]

You mean tripled. Just purchased the ultra twins dive rite setup from the LDS. plan on using it for my ice diving. Get that tank off my chest. Two SPG's, no big deal, I always check the other divers gauges during the dive anyway.

nh
I have been diving independants for alot longer than I have been on scubaboard. This is the first time I have seen this thread.
Toodles you would be proud of me in class tonight.
student: so let's say you had a freeflow at the turn point of the dive and lost your left tank gas supply
wedivebc: no problem I still have 1/3 remaining in my other tank, enough to complete the exit point.
student: OK so what if I was OOA at this point you would not have enough to get me out
wedivebc: if you were diving independants you wouldn't be OOA

[MikeFerrara]

I have been diving independants for alot longer than I have been on scubaboard. This is the first time I have seen this thread.
Toodles you would be proud of me in class tonight.
student: so let's say you had a freeflow at the turn point of the dive and lost your left tank gas supply
wedivebc: no problem I still have 1/3 remaining in my other tank, enough to complete the exit point.
student: OK so what if I was OOA at this point you would not have enough to get me out
wedivebc: if you were diving independants you wouldn't be OOA

I would have explained to the student that the gas in that tank is still useable by feathering the valve even if the free flow won't stop. Featherg the valve is especially easy if the independant tank is sidemounted. An OOG diver could easily feather the valve on your back as long as you don't have any restrictions to go through. A little free flow is no reason to act as if the tank is empty (or to let it empty in the first place) if you need the gas.

[padiscubapro]

Is ANDI the only agency that teaches how to dive either independants or manifold safely?

Does every other agency say "independats suck" and not explain why?

Of the people that trash independats, who has actually tried diving in this configuration for an extended period of time?

I am interested in hearing from people that have dove both for more than a couple of dives about their experiences.

I have heard from too many people that repeat what they have read without trying it themslefs. [To this someone could respond "I have read that jumping off a bridge is a bad idea, that does not mean I am going to try it." Don't tell me that. Diving independants a couple of times is not 99.98% certain to kill you.]

ANDI does have a specific protocol when using independent twins for gas use and how to configure the gear..

When using independednt swins the diver's left cylinder has an Extra second stage on a long ose so that Gas can be shared in an emergency..

We teach start on right cylinder, use 1/3 of gas, switch to left cylinder use 1/3 of gas, switch back to right and use 1/3 by the end of this use you should be near your gas switch point in most situations.. if a failure was to happen at this point, you would still have 2/3 of the left cylinder with 2 second stages on it (this is the equivalent of 1/3 the starting supply) plus whatever is stil in the right cylinder (1/3), so if your buddy had a failure you should have enough gas for the both of you..

[wedivebc]

We teach start on right cylinder, use 1/3 of gas, switch to left cylinder use 1/3 of gas, switch back to right and use 1/3 by the end of this use you should be near your gas switch point in most situations.. .
Actually the protocol is 1/3 from the side with the long hose, (reg switch), 1/3 from the other side (turn dive) 1/3 from the same side (reg switch) 1/3 from 1st side, end dive. This method involves only 2 reg switches and is less task loading than the method you outlined. It may be different in the ANDI trimix manual but the guy who introduced the protocol to Ed, (Harry) teaches it this way.

[wedivebc]

I would have explained to the student that the gas in that tank is still useable by feathering the valve even if the free flow won't stop. Featherg the valve is especially easy if the independant tank is sidemounted. An OOG diver could easily feather the valve on your back as long as you don't have any restrictions to go through. A little free flow is no reason to act as if the tank is empty (or to let it empty in the first place) if you need the gas.

I agree but the whole point of this methodology is that a failure does not have to be life threatening if the diver is in a restriction or involved in an important task. I once saw a trimix student abandon his lift bag and reel when a gas failure was introduced just as he was preparing to deploy them. A highly unlikely scenario, yes but it was designed to show that diving independant can take away the urgency of managing a potential failure. Locating a guideline in a wreck is another example of a jeopordizing situation if you have to manage a gas failure. By the time the mass of bubbles have blown to the ceiling of a rusty old wreck how well will you be able to see the line?

[DA Aquamaster]

I was REQUIRED to have a two-valve manifold in order to get my cave certification.

I also dive with side mounts and do not have any difficulty monitoring the air in two tanks. I watch the gauges of course, but the tanks themselves remind me to keep them even. If I don't they will float me sideways.

The manifold keeps things simpler because there is only one gauge to watch. But, I don't think that the manifold is more safe.I have had to shop around a bit to find an instructor that is ok with independent doubles in a given course. If they are not rigidly opposed to independent doubles they are just concerned, like they would be with any other tech diver/student, that your configuration is clean, well ordered and that you know how to use it. Agency acceptance is normally not the problem, but specific instuctors can be.

[padiscubapro]

Actually the protocol is 1/3 from the side with the long hose, (reg switch), 1/3 from the other side (turn dive) 1/3 from the same side (reg switch) 1/3 from 1st side, end dive. This method involves only 2 reg switches and is less task loading than the method you outlined. It may be different in the ANDI trimix manual but the guy who introduced the protocol to Ed, (Harry) teaches it this way.

No the standard is VERY specific..

The left post has 2 second stages.. This Is the tank with the long hose..

the right post has a single second stage.. We always start on the right post.. No exceptions..

The following is right out of our text.. If Harry taught you otherwie well he made a mistake..

Start Of Text (from wreck text):





The procedure is to begin the dive on the Right Cylinder until 1/3 of the gas

from Right Cylinder is used. Then switch to the Left Cylinder. Breathe 1/3

of the gas from the Left Cylinder. At this point you have used 1/3 of the

total gas supply, therefore this is the turning point of the dive. Switch to

the Right Cylinder and continue to use this gas for the return (or to the

first deco stop). Should additional gas be required beyond this point,

switch backto the Left Cylinder.
If prior to or at the turn point, a catastrophic gas loss should occur
the diver will still have 2/3 of either cylinder with which to breathe from.
Additional gas should not be required on a well executed dive. At this point
the team should be breathing surface Air discussing the great dive.




End..




The same text appears in the ERD/TMD manual which Harry co-authored, so could you have mis-understood him?? There ARE questions on the final exam that you should have gotten wrong if you didn't understand this.

[scubafool]

Good thread, lots to think through.