Why Steel Doubles?

[elan]

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

Well how often do you remove your scuba unit underwater ? for that time I think there will not be a big deal to experience that small discomfort.

The lift is not changing unless you are over weighting yourself.

The big advantage with the HP steals would also be the dry weight of them will be lower. HP100 I believe is only 2 lbs heavier but requires 6lb less lead. That's 8lb for doubles.

Another thing is that weight is spread over the whole tank. This can be an advantage or a disadvantage. You can do the same of cause with the V-weights.

 

[elan]

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.

Buoyancy change is the same no matter what you dive and equals exactly to the amount of gas you breath.

 

[Dive0saur]

great points, but I myself am completely neg when giving steel doubles and any additional weight would cause drag =(

 

[TSandM]

Diveosaur, I live in the same conditions you do, and I dive steel tanks.

Why?

Because an aluminum 80 would require I add about 5 pounds MORE weight than I'm currently carrying, just to sink the tank. And 5 more pounds is 5 pounds I have to lift from the car, walk to the water, and carry up the rocks at Cove 2. My single tank gear weighs almost as much as I do; I have no desire to add to it.

In very cold water, where we dive, it's highly unlikely that just using a steel tank is going to mean you carry no additional ballast. With a single LP95, I still wear a 5 lb backplate, six pounds on my cambands, and TWENTY POUNDS of lead on a belt. Should I, in some unimagineable emergency, need to remove my rig, I'm not very positive. Even with double 85s, I still wear 12 pounds on my waist. If I dove double Al80s (which I really ENJOY here in MX) I'd be adding another six or eight pounds of lead, making my whole rig heavier and harder to schlep.

Steel tanks don't make as much sense in warm water with minimal exposure protection. But in cold water, having the tanks be part of your ballast makes generally good sense.

 

[elan]

great points, but I myself am completely neg when giving steel doubles and any additional weight would cause drag =(

Look if you are significantly overweight when diving steel doubles with no weigh at all they might not be a good option for you, use ALs.

For me they are a very good alternative. I use no weight at all with my double HP100 and my rig weights less on the surface that my friends' double AL80. So I get lighter rig with more air. And I'm only overweight slightly - this gives me opportunity not to squeeze my dry suit to the point I become cold.

 

[ScubaInChicago]

The way I go from steels to AL on two or three tank dives is by keeping the tanks equally weighted with a V-weight.

11 lbs (5 kg) V-Weight, cast lead | Extreme Exposure

keeps the same buoyancy characteristics and the weight off the belt.

 

[Dive0saur]

Very true, but this leads back to my original post. If you remove weight from the diver you run into a major problem when removing the scuba unit underwater, and I am not too impressed with those who believe that this skill can be accomplished with a completely neg scuba unit and a completely positive diver.

 

[Dive0saur]

Elan, can you preform a don and doff? in your current config?

 

[Dive0saur]

TS and M,Makes much sense for your config, But I myself have made several dives with only LP95's as ballast. I no doubt though see the benefit in a single config, steel all the way!

ps like the cove 2 ref

 

[elan]

Elan, can you preform a don and doff? in your current config?

yeah. you have to float up for some time but it can be handled. At some point it even helps as I don it over the head so being head down and the rig on the bottom just helps. It's not comfortable though but can be handled.

I still yet to experience the need to do that for real.