Why dive doubles?

[Ghostdiver]

This is a gear question disguised as a tec question so I thought I would post it here :D. I am deciding between a BCD and BP/Wings and it seems the primary issue is whether I want to dive doubles. I always assumed I would want to dive doubles because I am the adventurous sort, but I got to thinking--do I really want to dive doubles, what extra benefit, besides extra air, do you get? Will a steel or aluminum 120 do? I know this is a pretty basic, fundamental question, but my LDS is an hour away so I thought I would hit up the members of the board to get their input before making the long trek to chit-chat.

[MechDiver]

You don't dive doubles because you're an "adventurous sort". You dive them because you NEED them. If you don't know whether you need them, you don't.

A backplate/wing IS a BCD.

A bp/wing does not require the wearing of doubles.

Will a steel 120 do what?

Does anyone make an alum 120???

Diving doubles is NOT a "basic fundamental question", as you already appear to realize or you wouldn't have posted it in this forum.

Phil

[vlada]

within rec limits - i.e. 130 ft or whatever BSAC says in Europe, within NDLs etc., for me personally it was time to switch to doubles when i started thinking about deco dives and trimix

If you are thinking that is in your future (i.e. deco and trimix) you are probably better off with doubles

The benefits of doubels are numerous, but the skill level that is required is higher as well

NOt knowing what your experience level is or what you goals are, it is hard to make any specific recommendations

DSAO

Vlada

[Walter]

Doubles do not require a back plate. I've dived doubles for many years with a jacket BC.

[Bob3]

There are basically 2 main + 1 compelling reason for using doubles.
You guessed the obvious, having more air.
#2 is redundancy for penetration dives.
#3 is balance.
I tore my doubles (over 72 cu ft) down years ago, made them into singles. No longer doing any deco diving, I could just pop up & swap out tanks if I needed more air.
I kept the twin 40s & 50s that I had as doubles because their balance is just so sweet, a heck of a lot nicer than a bigger longer single.
Besides, they look cool. :mean:

[roturner]

Ghostdiver once bubbled...
This is a gear question disguised as a tec question so I thought I would post it here :D. I am deciding between a BCD and BP/Wings and it seems the primary issue is whether I want to dive doubles. I always assumed I would want to dive doubles because I am the adventurous sort, but I got to thinking--do I really want to dive doubles, what extra benefit, besides extra air, do you get? Will a steel or aluminum 120 do? I know this is a pretty basic, fundamental question, but my LDS is an hour away so I thought I would hit up the members of the board to get their input before making the long trek to chit-chat.

In addition to what the others have said, you might want to consider doubles if you dive nitrox in moderate depths (around 30m give or take). At these depths you get enough benefit from nitrox that your air supply can become the limiting factor.

R..

[Walter]

Bob,

Do you have a set of triple 40's? Those are cool.

[Northeastwrecks]

IMHO, the single biggest reason to use a BP/Wing is COMFORT, regardless of whether you use singles or doubles.

I dive singles (Pioneer 36) and doubles (Explorer 55). My tanks vary from single AL63's to dual 104's. I can change the rig over in about 30 minutes.

I've never worn a more comfortable rig.

That said, you only need to consider doubles when your diving warrants it. IMHO, you should be totally comfortable with a singles rig before going to the added complexity of doubles.

[Big O]

As Rorurner states, you can buy the nitrox to do whatever dive you want (with the proper training) to do a deep dive. At that depth, consumption becomes a real issue. Sure you can dive a hp100 or a lp 120 with a pony or whatever at that depth, but its justas easy to dive doubles. With much more saftey gas on your back.

Dive doubles,

Dave

[Walter]

I've never found a back plate and wings to be as comfortable as a jacket.

[Bob3]

Do you have a set of triple 40's?

Nope, not yet. Haven't found the right match of condition & price.
:mean:

[Walter]

I lost touch with a buddy of mine (also named Bob) who had a set he picked up new in '58. He was still diving them in the early '90's, he might still be diving them.

[MikeFerrara]

Walter once bubbled...
I've never found a back plate and wings to be as comfortable as a jacket.

Just the oposit here. After trying a backplate I will nver again even consider diving in any bc especially a jacket.

[WYDT]

MikeFerrara once bubbled...


Just the oposit here. After trying a backplate I will never again even consider diving in any bc especially a jacket.

Ditto that Mike!!

Ohh and can someone remind me what year this is? I'm getting confused with Bob and Walters talk of 72's and triple 40's. ;)

[MikeFerrara]

This being the tech section and all...

If I have to do much deco rather than use triple 40's I use two 80's. As far as doubles I'll keep my 104's. I might double a set of 72's for a tech dive to 60 feet.

Where do you put reels or backup lights on a jacket?
ok so I'm opinionated.

[Wreck/Tec]

Keeping in mind everyone is different and entitled to their opinion..........I prefer a SS back plate and wing to any other sys for doubles. They are secure, and I remove any weight from my waist through the addition of gear. As for useing tripples, or unusual configurations like that, the expense of binding them together, the addition of manifolds and running more hoses is unnecessary when a larger set of tanks will reduce cost, risk, and contribute to being more streamlined. Those of you who do doubles just for deep dives, that's great. I however use them for most boat dives, because I don't have to chase tanks, I feel more secure having the air as opposed to wanting more. My ballance is better with the doubles. I like having all the reels, lift bags, stages, etc., it's a nice to be able to manage all that stuff. I wouldn't be carrying it if it weren't for the harness and back plate. On the other hand........They can be heavy! I do alot of shore diving. There I prefer a 120 or 135 and an 80 for a pony. I have knee problems and don't want to carry all that stuff to the water at one time. Doubles are an excellant way to extend your BT in shallower water if you choose. They are a must for deeper diving as you have to consider enough gas for your partner in the event of trouble. In this country people buy things not so much out of need, but want. Get them if you want them.........JUST make sure you know how to USE them correctly, and safely. You don't strap them on and go...........If you have questions ask, or consult an accretted agency first!

[Ghostdiver]

Thank you everyone for your kind and informative answers to a novice. It sounds like there are four primary reasons for using doubles:

(1) Extra air for non-deco diving with nitrox @ 100’/30m
(2) redundant tank for wreck diving (I assume this requires two regs as well?)
(3) balance (Bob are you referring to doubles being more balanced than diving a single with a pony bottle or are they just better balanced than singles in general?)
(4) Decompression diving

As I am a beginner (<25 dives) I won’t be using doubles in the near future. I am not sure I will ever get into deco diving, as my time and wallet may not allow me to do it right & safely. But I will definitely dive at 100’ with nitrox and as I am a big guy, even when I become more efficient I may still be a bit of an air hog so I may go with doubles at that time. Since using doubles for me sounds likely in the future I will avoind the Stab Jacket -> Ebay -> BP or Doubles Jacket pattern and get a BCD capable of using doubles now. I will probably end up with a backplate since people seem very happy with them even with single AL80s tropical diving and if I eat my words 5-10 years down the line, I will be able to switch to deco diving.

If the time comes that I want to switch to doubles for non-deco diving (for air consumption on nitrox at 100’) is there a specific course/training agency anyone would recommend? And can you do wreck penetration in N.C. without deco diving?

[O-ring]

And can you do wreck penetration in N.C. without deco diving?
There isn't a whole lot of penetration on a lot of the NC wrecks, but stuff like the Indra can be penetrated easily without racking up a deco obligation.

[Northeastwrecks]

Like Wreck/Tec, I use my doubles for most of my dives. Given the choice of carrying the weight in the form of large tanks with tons of gas or as otherwise useless lead shot, I'd rather have the gas.

Besides, using the doubles on shallow dives is good practice for other stuff.

I still use my singles for some shore dives.

Going with the BP is probably a good idea. Its easy to switch from singles to doubles if you so desire. In the meantime, you will have a nice singles rig that, IMHO, is quite comfortable.

Good Luck

[Gorji]

MIKE YOU crack me up with your humor!!!!.

Thanks.

[Joe R.]

One mans rubbish...as the saying goes. I dove jackets for years. Loved my Black Diamond. Until I took an Advanced Nitrox course and the instructor suggested we use the same gear. ss backplate with wings. Better streamline, definetely less drag. Have 2 backplates now and while I think its good to learn basic scuba with a jacket bc. You should move quickly to wings if your serious.:flame:

[aquanut]

If you have to ask..............
stay away from them, you're not ready.

[The Pirate]

Why don't you just get a Big Johnson and be done with it?

The Pirate

[Jonathan]

I dive them on recreational dives for balance and also much more comfortable (which I still find bizarre when you look at them).

Another benefit when using them and boat diving you don't have to change tanks in between dives (recreational of course) which give me more time to get tea and biscuits down my neck!

Jonathan

[willanz]

In a past life, I used a jacket BC (2 of them), then a soft pack back inflation and then started diving doubles. After my first try with the backplate/wing/harness set up, I sold the rest of my gear. (I even traded the soft pack back inflation BC for carpeting in room :D )

I moved to South Florida (Jan 2002) picked up a single tank wing and a couple of single Al 80s. I lasted about 9 months diving that set up. I sold the rig and all 4 of my regs (2 back gas, 2 stage regs) and replaced it with a manifold, bands and 2 quality backgas regulators.

Now I have my PST 104s for the Caves and my AL 80s for anything else. It makes a huge difference to go back to cave diving after 2 months off and have minimum rust on diving doubles.

It's going to be very hard to get me back to diving single tanks.

I think most of the benefits have been pointed out already. I like not having to switch tanks in between boat dives.

One big disadvantage:

The local shops keep putting on a fill whip in each valve to fill them.

It takes a couple of fills to train them.

[Rush]

After diving doubles, for me the real question is, why dive anything other than doubles ?

In all seriousness, Ghostdiver, get comfortable diving with a single tank. Once you are experienced with that set up, if you feel that the type of diving you will be doing would necessitate diving doubles, get proper training. When you begin to dive doubles, you will feel like you are starting all over again.

[MikeS]

Rush once bubbled...
why dive anything other than doubles ?


Top 10 reasons for not diving doubles.

1. It’s not practical to carry them on the airplane and you can’t rent them when you get there.

2. They’re expensive and I’d rather spend the money on a dry suit.

3. On recreational dives with an HP120s I hit the NDL before my dive plan says to surface based on air.

4. They’re too dang heavy to lug from the car to the quarry.

5. I’d have to buy another wing since my Pioneer won’t work with doubles.

6. A pony bailout bottle gives me 100% redundancy.

O.K. I could only come up with 6, maybe someone else can help me out.
Of course all these reasons go out the window if I decide to do decompression or penetration diving.

Mike

[MikeFerrara]

MikeS once bubbled...


Of course all these reasons go out the window if I decide to do decompression or penetration diving.

Mike

If you not the whole question is rather moot.

[Rush]

In response to your Top 10, er, Top 6 Reasons not to dive doubles:


1.) Sites I've gone to in Mexico and Florida have had doubles
available for rent or as part of the dive package.

2.) I went the other route; doubles first, dry suit later. With the
caves I have experienced, the money for the tanks and the
training was well worth it !

3.) Doubles have enabled me to spend hours exploring caves.
With the additional training, decompression dives are
possible, therefore extending your bottom time.

4.) I dive Faber steel 112's; they were heavy at first, but then
I got used to the weight.

5.) Again, the experiences, IMO, have been worth the expense.

6.) A Pony does not contain the additional air necessary to do
as long of duration dives as doubles would.


When you want to increase your fun, you should try doubles (with proper training, of course !)


:) :) :)

[MikeS]

MikeFerrara once bubbled...


If you not the whole question is rather moot.

Mike,

That was my point, as far as I have figured out with my limited experience, if you’re not diving penetration or stage decompression there isn’t much justification for doubles.

Rush,

If I was going to do penetration diving, “exploring caves,” than doubles would make sense. But for non-penetration with no stage decompression diving I don’t see the point.

Mike

[Rush]

Yeah, until I began diving doubles, I didn't see the reason for them. Once trained, I realized that diving which requires doubles is the diving that I enjoy the most. In a non-penetration, non-deco diving situation, I still prefer to use my doubles...I still get benefits....I don't have to lug my tanks to the airfill station or switch tanks like my AL80-wearing buddies do when we are doing a few dives a day.

Just having fun,

[Dyno Bill]

OK you guys, I have used a lp steel 95 for years and in my diving I never run out of air but you mention the balance thing. I am into the comfort thought as I am a little older and perhaps balance would be a good thing. I was wondering if anyone had any experiance with twin 50,s. They would be shorter and give a little more volume so does anyone have any experiance with this particular setup and if so how did or does it work for you.
Bill

[cast55]

The only reason for diving doubles is the component failure survival probability (when used with an isolation manifold). Any dive with a real or virtual ceiling requires redundancy in the form of failure responses which do not entail surfacing immediately. To put it another way, use doubles on any dive that you can't make a free swimming out of gas ascent from.

I have two backplate/harness/wing setups - for singles and doubles.

-Sean

[Dyno Bill]

Thanks for the explanation, although I do fully understand the concept of complete redundancy when entering an overhead environment and that is a point well taken. I actually have all the setups for that eventuality and have used them on numerous dives. I was actually asking if using a set of shorter doubles would be more balanced in the water. I dive a LP 95 off dive boats and it actually does a nice job. I dont enter wrecks as a rule as there arnt all that many around here and if I did I would take the appropriate cautions as I have for yrs. All the chat about doubles just re-kindled a old curiosity and perhaps nothing more than that. Thanks again
Bill

[blackice]

Walter once bubbled...
Bob,

Do you have a set of triple 40's? Those are cool.

Haha love to see a pic, what is next quad 30's?

[DA Aquamaster]

Dyno Bill once bubbled...
OK you guys, I have used a lp steel 95 for years and in my diving I never run out of air but you mention the balance thing. I am into the comfort thought as I am a little older and perhaps balance would be a good thing. I was wondering if anyone had any experiance with twin 50,s. They would be shorter and give a little more volume so does anyone have any experiance with this particular setup and if so how did or does it work for you.
Bill

It has been at least 15 yrs since I used two sets of twin 50's (a set of 2015 psi steel tanks and a set of 1800 psi steel tanks) and I honestly don't remember much as to stability other than the impression that I did not have any problems with stability with them. The two sets I had ended up separated for use by my spouse and son.

I think that in general a properly mounted set of doubles is very stable and would be preferable to a large single tank. This is though a personal preerence. Stability is also perhaps more dependent on the wings you use as they need to be properly sized for the tank(s).

I normally dive with a pair of steel 72's as I have a low SAC rate and really don't want or need anything larger for the diving I do. In my experience, a more bouyant set of 80's gives you more of a feeling of being suspended from a blimp in terms of excellent stability given where that bouyancy is located while heavier steel tanks are a little more neutral in this regard.

[zeN||]

Interesting thread, can you guys state why/in what way are the wings/backplates more comfy than a jacket style please thanx zeN

[Dyno Bill]

Thanks DA, I have a pile of old 72's and I dive a Dacor Rig which will carry doubles no problem.
Bill

[DA Aquamaster]

I have always been a back inflation fan. In my opinion, the aircell being above you lends more stability when underwater. With doubles the aircell is also quite well supported from above and there is very little air shifting.

The chief floatation related complaint of a backplate/wing or back inflation BC is that they can tip you face down on the surface. However I have not found this to be a problem in most of the bacl floatation devices I have owned and used with single tanks as long as you use trim weights and take some care not to overfill the bladder on the surface. With doubles, I have not found trim weights to be needed and have found in my case that I have to fill my 75# wing all the way to even get a hint of forward lean on the surface.

[Grumman581]

I started diving doubles back around 1981 in Florida when we were hitting some of the cave systems while I was stationed in Orlando... Back then, it was normal AL80s with a manifold that connected the two J-valves together... Some people say that they have had problems with that type of manifold, but I never did...

I tend to dive solo (even when I'm cave diving), so instead of manifolded doubles, I dive independent doubles... I went with AL80s since I'm able to take my BC with the bands attached on dive trips that require flying on commercial airliners... Thus, when we go to Coz, I can dive the same configuration that I dive locally... I tend to dive deeper than the rest of the boat, so I use up more air... Since I dive solo, I have to have fully redundant systems...