Why Steel Doubles?

[The Chairman]

Did you think of keeping the leaky inflator at the lowest point? Problem solved with physics.

 

[TSandM]

While I was in MX, I heard a story from some friends. They were diving a site where the entry opens into a small room with heavy mung on the bottom. (For those who don't cave dive, mung is fine, organic debris. It is very light, and stirs up easily and stays in the water quite a while.) A diver came out of the cave and sheepishly confessed that he had "made a mess in there". He was diving a bungied wing and the inflator hose had either come off at the fitting on the wing or had broken. Either way, the wing rapidly deflated itself and he went splat! into the bottom, and had to crawl out.

It's rare, but it can happen. And as with all things in diving, the decisions you make about your gear come from doing the best risk assessment you can, with the information available to you.

Dumping canister lights isn't useful any more . . . that whole concept came from the days when people dove large lead-acid batteries that weighed a ton and were very negative. Dumping a 200g NiMH battery isn't going to get you very far!

 

[pvcole]

TSandM,

What are you using for camband weight pockets? I am looking to add a plate and trade the 30 lb Dive Rite weight pouches for the 18 lb pouches but need a place to hold a few pounds of trim weight.

Thanks in advance,
Perry (Carnation, WA)

 

[pvcole]

Sorry, posted before I read the thread. I should have read all the "you will die" posts first, but here is my question, after a little background. All my tanks are high pressure steel, two each of 80, 100, and 119 cf capacity. I dive dry in the winter and wet in the summer and alternate between a Zeagle Tech and a TransPac.

So, if I want to die later rather than earlier, should I twin up the 80s and dive the Tech with my dry suit or twin up the 119s and dive the Transpac with my wetsuit. There were so many combinations of tank material, tank capacity, and exposure suit types that I got lost in which would cause me to die faster that the other.

I do not have any emoticons because I truly want to die later rather than earlier.

 

[StreetDoctor]

If you're diving steel doubles it's my recommendation you should be diving dry.

 

[Gilldiver]

If you're diving steel doubles it's my recommendation you should be diving dry.

The above is very simplistic and ignorant. It's not "Don't dive steel tanks wet", it should be "Don't dive heavy tank configurations when wet be they steel or aluminum wet." After all the first 30 years of diving used steel tanks almost 100% of the time and steel double 38's, 50's, 63's, and 72's were quite common.

Joel Silverstine did one of the best write ups on steel tanks on another board.


B A L A N C E ..... balance.

Much of the "dont dive steel with wetsuits" information came out of South Florida in the mid 1990s when DIR / GUE / WKPP programs were being created. Much of this had to do with diving PST 104s with 3MM wet suits .... that in and of itself is a big ole problem larger than we have room to argue over. Since they were not going to change steel tanks aluminum was the logical choice.

Steel cylinders have been in use with wetsuits much longer than aluminum cylinders have been. Go back to the beginning before alum cylinders were made for scuba.

Different steel cylinders have different bouyancy charachteristics. Some are rock heavy, some are light as a feather (figurately speaking) 7, 7.25, 8" cyliners all are different and displace different amounts of water. And each diver is different in displacement as well.

Remember that a BC / Wing is not an elevator it is a "compensator" it is to compensate for the decrease in thickness of an exposure suit and the compession of the air in the wing and lungs as one goes deeper. In an ideal world all you really need is enough lift to make you 1 lbs positive and you can then swim up. But the real world does not work that way and we have to sometimes overcompensate for stability with additional balast for control.

My favorite cylinder with a 5mm wet suit in fresh water is a Faber 95. With a 3mm a Faber 85. I can glide -- move to salt water and I will add a little weight to compensate for the salt water.

For doubles it gets a little more involved because of the weight of the bands and manifolds but still manageable.

I have found that Faber LP steel cylinders have a cleaner buoyancy swing than the X cylinders have. And when not overfilled they balance out very nicely with wet suits.

Aluminums tend to be a bit floaty and will require 8 lbs of neutralization balast to be added for just the cylinders.

Assuming the balance of the rig can be created and, we know it can, the big question comes down to this.

"What is the probability that a dive wing will fail and provide zero lift?"

Since 1989 when I started to dive with wings. I have had 3 wings provide some problems in

Wing 1. Dive Rite Classic wing - 1800 dives on it developed pin hole leaks at the welding seam. (did not lose buoyancy - replaced cell)

Wing 2. Halcyon Single Wing - 20 dives on it snagged wing on piece of wreckage on the Rhone and got small hole. (Halcyon could not repair or replace - I threw it out)

Wing 3 Inflator cracked due to HP seat failure in regulator. Wing held air as hose was below the bubble level.

Dive equipment rarely fails. When it does more than 95% of the time it has to do with a maintenance issue which falls back to user issue.

Divers need to learn how to inspect equipment pre and post dive. This will lead to few if any failures. Care for equipment on boats is important as well. Keep your gear tidy. In your space and not all over the place and it will rarely if ever get damaged.

So to answer the OPs question. .... Yes you can dive steel tanks with a wet suit so long as the rig is balanced and you can swim it out should you have ZERO ability to inflate the wing. The balance is something that is based upon your size and needs and the needs of your team.

cheers
JDS

 

[StreetDoctor]

None of the tank sizes you noted were mentioned by the poster asking the question. Also like I said, "it's my recommendation". That hardly makes me ignorant, I like having some form of redundant buoyancy without having to worry about trying to swim up 15-20lbs from depth. I posted my math a few pages back, it's your choice where you draw the line. The common number I've read is 10lbs is about as heavy as you'll be able to swim up from depth.

 

[ScubaInChicago]

None of the tank sizes you noted were mentioned by the poster asking the question. Also like I said, "it's my recommendation". That hardly makes me ignorant, I like having some form of redundant buoyancy without having to worry about trying to swim up 15-20lbs from depth. I posted my math a few pages back, it's your choice where you draw the line. The common number I've read is 10lbs is about as heavy as you'll be able to swim up from depth.

But my AL80's weigh more than 10lbs...

 

[StreetDoctor]

But they aren't negatively buoyany by 10lbs

 

[elan]

Balanced rig talks are good until you have 15-18 lb of air not only to swim up but also stay afloat on the surface.

But yeah balance is important. I cannot logically see how one can make say HP120 or HP130 doubles balanced and being able to be swum up Especially if you have stages or deco bottles which for example are not disconnected and are part of the weighting calculations