Why dive doubles?

[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...