Why Steel Doubles?

[Dive0saur]

So I've done much reading as to why people prefer steel tanks for doubles. Over and over again I hear people say they prefer the buoyancy characteristics. Without getting into numbers Steel tanks offer the diver the ability to remove weight from oneself to the scuba unit. For a long time I was right there with everyone, I mean this sounds great for those who are doing cold water dives such as myself.
But i can not get over a few simple facts I have yet to see anyone address. The more obvious one is Lift requirement for these heavy tanks. I believe this to be a significant draw back to using steel tanks. A diver should be able to float their scuba unit independent of the diver and with these heavy steels much more lift is required "verses AL of course"
And finally the most important issue i can think of. For someone such as myself diving heavy steels will not require me to dive any other weight, and so this begs the question "what if I need to remove my scuba unit while on a dive!?" without adequate weight on a diver he would become so buoyant that the tanks would do down and the divers feet would go straight up.
It would seem to me that a diver should attempt to get his scuba unit neutral independently as well as himself.
Please post any wisdom or opinions you may have. Thanks for your time
Dive0saur

 

[walke121]

Size is probably the most common reason. Not as much buoyancy change during the dive. The lift requirement isn't that big of an issue. Most people that dive large steel doubles dive dry so you will need some weight. Even in 77 degree water it can get chilly after 2 hours.

 

[giles45shop]

One reason is that the largest aluminum tanks are only 100 ft3 and can't be overfilled. So the greatest volume of gas is 160-200 ft3. In cave diving, you routinely see double 130's or low presure steel tanks overfilled to higher capacities (my double 95's w/ 3600 psi hold 259 ft3).

 

[RonMurray]

Value is also a factor - at least for me.

True, AL tanks are cheaper. But steel tanks last forever (as evidenced by my 33 year old 72CF)

I expect my 95 doubles, and 104 doubles to also last a very, very long time. And, when you think about it - given the amount of money I have spent on SCUBA equipment, it's good to know my kids will inherit SOMETHING.

 

[ScubaInChicago]

I understand your question, but your logic is slightly flawed. Doffing you equipment underwter would usally be done while being nuetrally bouyant. Here's a video of someone doing it in tech gear (not the greatest example but relays the idea). It can be done with a drysuit which make it slightly more difficult but really it's just as easy.

YouTube - Technical Diving - Gear Removal/Replacement

 

[Dive0saur]

Yes... Sorry but your logic is flawed, this is a diver in AL bottles and no drysuit... has nothing to do with this post what-so-ever

 

[ScubaInChicago]

Yes... Sorry but your logic is flawed, this is a diver in AL bottles and no drysuit... has nothing to do with this post what-so-ever

The tanks are not the question, the weight is all on the rig regardless...

 

[Dive0saur]

giles45shop, great point, capacity is very important. But I'm not sure I will be jamming LP bottles to 3600psi =( i take it your not the one that fills your bottles.

 

[Dive0saur]

yes it is the weight.. and AL bottles are much lighter... point n case

 

[fppf]

Aluminum tanks when empty are 4 lbs positive. So for a set of doubles you need to add 8 lbs just so the tanks wont float.

Most steel tanks when empty are 2 lbs negative or so. So you don't need to add any weight for the tanks and you can drop 4 lbs off the belts.

If you diving doubles your not in a shorty most times. And even a full 3mm suit will need a few lbs of lead.