Stages

[flw]

It works with out al tanks when they have helium in them.

I 'spose it probably does, I tend to use 16/50 as my bottom gas bail out, which is far too floaty and gets in the way in an Al cylinder, but I've never tried getting rid of it on the way back up (yet)
Anyways I'm supposed to be studying, not thinking about diving - after 18 years I just started another degree, and I'm finding it a bit hard getting back into the swing of studying

 

[IndigoBlue]

I personally use all steel for back gas and deco. And have not had any issues. This allows me to remove weight from my belt.

It is just a matter of balancing the your weighting no matter which tank you use.

DSAO

I have never seen anyone use steel stages, but thanks to Dan's explanation, I can see that it would make sense IF done properly.

For tech diving, I usually have about 10 lbs on my belt in cold water. That roughly equals the sum of my breathing mix in my backgas doubles. So if I ditched my belt early into a tech dive, I would still be neutral, without using my B/C or my suit for inflation. My belt would be the only thing left on the ocean floor. I could bring all my stages and gear back with me.

With steel stages, my belt would decrease to 6 lbs or less. I would probably then need to ditch a steel stage or two, to become neutral, in addition to my belt. And that would mean also leaving behind the 1st and 2nd stages and SPGs attached to them. Ouch.

For perfect trim and buoyancy, on any dive, you would want your ditchable weight to equal the weight of your breathing gas, when diving with a drysuit or with a very thin wetsuit like 3mms. The rest of your weighting may be nonditchable. Where you mount the nonditchable weight will affect your trim. Counting the steel stages as trim weights, and locating them to either side of you, would give you pretty good trim.

As long as ditching your ditchable weight on your belt allows you to be neutral at the beginning of your dive, when your breathing gas weighs the most, then you would be properly and safely trimmed. If you had to ditch a steel stage in addition, well cost is the only factor there. I would be crying if I had to do that, however.

That is the only disadvantage I can see to steel stages, other than their cost. I suspect steel stages probably cost more than aluminum stages.

 

[matt_unique]

You do need to plan for the fact that you might have to ditch all of your tanks. (you would be foolish if you didn’t) If you have the proper Wing or BC you will be able to carry the extra weight of the deco bottles.

Then if you do need to ditch the tanks all you need to do is to dump some air out of your wing.

I personally clip off my deco tanks to an equipment line prior to getting back on the boat. It just makes it easier to climb a latter.

Why would you need to plan to ditch your tanks, short of entanglement as I mentioned before? Have you ever "had" to drop tanks or other gear on a dive?

I have my weight configured for what I take with me. If I sling a deco bottle I will put more weight on the opposite side as a counter balance. I will reduce my overall weight to account for the configuration. I dive with single steel 120's/H-valve. If I hard connect my deco bottle to the tank I will configure my weight a bit differently to prevent rolling. My BC has the lift for extra weighting but I don't see the point to the extra air volume.

 

[MikeFerrara]

Why would you need to plan to ditch your tanks, short of entanglement as I mentioned before? Have you ever "had" to drop tanks or other gear on a dive?

As I said we drop them in caves

I have my weight configured for what I take with me. If I sling a deco bottle I will put more weight on the opposite side as a counter balance. I will reduce my overall weight to account for the configuration. I dive with single steel 120's/H-valve. If I hard connect my deco bottle to the tank I will configure my weight a bit differently to prevent rolling. My BC has the lift for extra weighting but I don't see the point to the extra air volume.

We don't hard connect a decompression bottle we sling it. With an al80 or even several you don't need a counter balance.

Again remember that while you need some weight with a single 120 that isn't the case with all configurations. For instance, most divers don't need any additional weight with double 104's (a common tank). There isn't anything to balance because there isn't any weight belt or anything else. With al tanks there's no need to shift weight to compensate.

 

[matt_unique]

As I said we drop them in caves

We don't hard connect a decompression bottle we sling it. With an al80 or even several you don't need a counter balance.

Again remember that while you need some weight with a single 120 that isn't the case with all configurations. For instance, most divers don't need any additional weight with double 104's (a common tank). There isn't anything to balance because there isn't any weight belt or anything else. With al tanks there's no need to shift weight to compensate.

I understand the need to be able to drop deco bottles for cave purposes or other sort of entanglement problems. I got the impression from NEWreck Diver that he considers the need/contingency plans to drop deco bottles for other purposes.

--Matt

 

[GDI]

I use a steel 72 for my O2 in caves but have a AL 30 for my O2 in OW. All my other deco tanks are AL. In a cave they (AL) usually float up and if secured correctly they don't impact the cave (on me or when snapped to the line). Remember in a cave I am not carrying what I don't need. In the OW AL has the advantage of floating to the surface when empty if needed to discard and can be later recovered. The weight of either is a big factor getting to or in the water. On a wreck it all comes with me. You'll need to ballast yourself so as to maintain correct trim AND have access to each tank valve. Play in shallow water first with full and empty (< 700 psi) deco tanks

 

[NEWreckDiver]

I understand the need to be able to drop deco bottles for cave purposes or other sort of entanglement problems. I got the impression from NEWreck Diver that he considers the need/contingency plans to drop deco bottles for other purposes.

--Matt

Yes I do. You do need to plan for the unforeseen. That is and always has been my point.

Who knows what may happen, the better the contingency plan, the better the chances of surviving a problem.

DSAO

 

[NEWreckDiver]

I use a steel 72 for my O2 in caves but have a AL 30 for my O2 in OW. All my other deco tanks are AL. In a cave they (AL) usually float up and if secured correctly they don't impact the cave (on me or when snapped to the line). Remember in a cave I am not carrying what I don't need. In the OW AL has the advantage of floating to the surface when empty if needed to discard and can be later recovered. The weight of either is a big factor getting to or in the water. On a wreck it all comes with me. You'll need to ballast yourself so as to maintain correct trim AND have access to each tank valve. Play in shallow water first with full and empty (< 700 psi) deco tanks

Here, Here. This is very good advice.

 

[matt_unique]

Yes I do. You do need to plan for the unforeseen. That is and always has been my point.

Who knows what may happen, the better the contingency plan, the better the chances of surviving a problem.

DSAO

OK, you're saying just in general it's important to plan for contingency. I agree with that fully. I thought there was a specific instance you could share where you had to drop a bottle and were able to avoid buoyancy problems because you trimmed your weight without bottles.

Of the ways I plan for contingency, I do not factor in loosing my deco bottle. (Again my dive profiles presently require only 1 deco bottle). Unless there is a special need I choose to hard attach my deco bottle to my primary tank. I like it because it's out of the way (running cleaner), my weight is trimmed such that I have no roll, and it's ready to go upon inhale. I of course have an SPG routed such that I can always verify the pressure. During training we had to demonstrate removing/reattaching the deco bottle. The difference in weight for one AL 40CF is such that you would not significantly affect your buoyancy.

I can imagine if you had 4 bottles and had to drop them all, and if you trimmed your weight with the bottles, you would of course be quite light.

--Matt

 

[NEWreckDiver]

OK, you're saying just in general it's important to plan for contingency. I agree with that fully. I thought there was a specific instance you could share where you had to drop a bottle and were able to avoid buoyancy problems because you trimmed your weight without bottles.

Of the ways I plan for contingency, I do not factor in loosing my deco bottle. (Again my dive profiles presently require only 1 deco bottle). Unless there is a special need I choose to hard attach my deco bottle to my primary tank. I like it because it's out of the way (running cleaner), my weight is trimmed such that I have no roll, and it's ready to go upon inhale. I of course have an SPG routed such that I can always verify the pressure. During training we had to demonstrate removing/reattaching the deco bottle. The difference in weight for one AL 40CF is such that you would not significantly affect your buoyancy.

I can imagine if you had 4 bottles and had to drop them all, and if you trimmed your weight with the bottles, you would of course be quite light.

--Matt

Yes, you never know what may happen.

Also it is a good idea to have your deco tanks ridged so that you can cut them away if case you need to instead of having them connected with metal rings or links. In your case, you have your stage rigged like a pony and there really is only one way for that.

So back to the original question here, there are positives and negatives to both aluminum and steel. You need to find which works best you.

There is always more than one way to skin a cat.

DSAO