steel aluminum tank
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Soggy
Contributor
BKP:
Someone's a little touchy.
SparticleBrane
Contributor
I was under the impression that the buoyancy swing resulting from wetsuit compression is the important factor, not the compression of the wetsuit itself. 
Charlie99
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For most of us, the context of Seiff's post makes that clear. Situational awareness helps when topside too.SparticleBrane:I was under the impression that the buoyancy swing resulting from wetsuit compression is the important factor, not the compression of the wetsuit itself.
SparticleBrane
Contributor
You should read the context of my post as well.Charlie99:For most of us, the context of Seiff's post makes that clear. Situational awareness helps when topside too.
I knew quite well exactly what he was talking about, but wanted to get him to say what he meant, rather than what he said.
OP
seiff
Registered
In the interest of saying what I mean to say, and meaning it....then saying it.....??.......
1) Sparticle: you are right, the effect on boyancy is what I'm talking about, however some people argue that insulation is also affected by compression. I said that this compression is dangerous because anything that throws your buoyancy off is a safety issue, which leads me to...
2) Soggy: like I mentioned from the beginning , I have myself discussed the neoprene+steel issue "ad noseum", but never with DIR folks, and it is this viewpoint I am trying to corner so thanks for keeping things relevant to the forum. I am getting the idea that the swing of an aluminum tank from negative to positive is an intentional part of DIR/Deco diving. This is not the diving I'm doing, although I really want to get into it (and so I am posting stuff here), so let's get away from my initial concern about single steels on a REC dive.
Stages and deco's should always be aluminum, and most doubles you guys use are LP right? So here is an additional point I would like info on from a DIR POV, which I think is still appropriate to continue this thread with:
What is the mentality behind using tanks that swing this way (lol)? I understand that most overhead/deco divers do not use additional lead weight, so how does a DIR diver utilize the swing of the tanks as a constructive part of his buoyancy control? Is this clear enough? -tadd
1) Sparticle: you are right, the effect on boyancy is what I'm talking about, however some people argue that insulation is also affected by compression. I said that this compression is dangerous because anything that throws your buoyancy off is a safety issue, which leads me to...
2) Soggy: like I mentioned from the beginning , I have myself discussed the neoprene+steel issue "ad noseum", but never with DIR folks, and it is this viewpoint I am trying to corner so thanks for keeping things relevant to the forum. I am getting the idea that the swing of an aluminum tank from negative to positive is an intentional part of DIR/Deco diving. This is not the diving I'm doing, although I really want to get into it (and so I am posting stuff here), so let's get away from my initial concern about single steels on a REC dive.
Stages and deco's should always be aluminum, and most doubles you guys use are LP right? So here is an additional point I would like info on from a DIR POV, which I think is still appropriate to continue this thread with:
What is the mentality behind using tanks that swing this way (lol)? I understand that most overhead/deco divers do not use additional lead weight, so how does a DIR diver utilize the swing of the tanks as a constructive part of his buoyancy control? Is this clear enough? -tadd
Tadd,
The problem with double steels is that you may need no weight at all, or even be overweighted with the tanks alone. In a wetsuit, at depth, very negative from the gas you're carrying, and with nothing you can ditch, you are left with the only option being ditching your tanks if you need to get to the surface. This is why a drysuit is recommended for diving doubled steel tanks, and also for diving to significant depth. The interplay of tanks which provide all your ballast, and exposure protection which loses its buoyancy, creates the possibility of a major problem at depth.
With aluminum tanks, you are almost certainly going to have to carry ballast to sink them, and that ballast COULD be dumped if it had to be.
A better solution for deeper diving is a dry suit, which doesn't change buoyancy with depth. Then, you are only negative by the weight of the gas you are carrying -- which, with doubles, can be considerable -- And assuming you are correctly weighted, you will be the same amount negative with double Al80's or with double steel 80's. So you are right that the swing is the same. The difference is the ballast, which is in the tanks in steels and in some other weight source with aluminum tanks.
The issue is only really pertinent when diving wet. A thick wetsuit loses buoyancy at depth, and a thin one may not ever get you neutral with doubled steels. In either case, you are exquisitely dependent on your wing, and in the DIR philosophy, if you're dependent upon it, you take two -- eg. dry suit.
The problem with double steels is that you may need no weight at all, or even be overweighted with the tanks alone. In a wetsuit, at depth, very negative from the gas you're carrying, and with nothing you can ditch, you are left with the only option being ditching your tanks if you need to get to the surface. This is why a drysuit is recommended for diving doubled steel tanks, and also for diving to significant depth. The interplay of tanks which provide all your ballast, and exposure protection which loses its buoyancy, creates the possibility of a major problem at depth.
With aluminum tanks, you are almost certainly going to have to carry ballast to sink them, and that ballast COULD be dumped if it had to be.
A better solution for deeper diving is a dry suit, which doesn't change buoyancy with depth. Then, you are only negative by the weight of the gas you are carrying -- which, with doubles, can be considerable -- And assuming you are correctly weighted, you will be the same amount negative with double Al80's or with double steel 80's. So you are right that the swing is the same. The difference is the ballast, which is in the tanks in steels and in some other weight source with aluminum tanks.
The issue is only really pertinent when diving wet. A thick wetsuit loses buoyancy at depth, and a thin one may not ever get you neutral with doubled steels. In either case, you are exquisitely dependent on your wing, and in the DIR philosophy, if you're dependent upon it, you take two -- eg. dry suit.
underwasser bolt
Contributor
First, I am NOT DIR
BUT, the issue of wetsuit compression is obvious, as is the issue of wetsuit compression and tank issue. the issue is not the swing, which is consistent. it is going from negative/positive (al) or negative/negative (steel).
I don't see the need for wetsuits above 3mm at any rate; any colder than than, dive dry.
this is not DIR, it is diving with a brain, and understanding physics.
BUT, the issue of wetsuit compression is obvious, as is the issue of wetsuit compression and tank issue. the issue is not the swing, which is consistent. it is going from negative/positive (al) or negative/negative (steel).
I don't see the need for wetsuits above 3mm at any rate; any colder than than, dive dry.
this is not DIR, it is diving with a brain, and understanding physics.
OP
seiff
Registered
TSandM: Thanks for that, that addressed my original post very accurately. But coming away from that. I realize now that people on this site, especially this section, demand a very specific outline of what one is asking. (Perhaps I am used to the musician forums where everyone is barely coherent at all let alone reagarding the topic at hand.) So, escaping my original concern:
For consideration here:
-Dry suit, doubles (AL or Steel), and perhaps some stages.
-diving deep or overhead.
so, my question is: How do you guys (DIR) balance your rigs at all? I have heard the comment "you gotta be able to swim up your rig" tossed around, but is this not relevant to this type of diving? Regardless of that answer, what ARE some of the rules of thumb about balancing gear consisting of so many tanks?
That's it, just what do you consider a balanced rig in such an extreme situation, because it can't be based on the same principles as single tank/REC/wetsuit diving. This is what I am curious about.
underwasser: Here in SoCal you couild go surfing in your trunks, but it's cold enough even when the water is warm to really chill you fast if you're diving. But 68 degrees is not automatically dry suit time, especially when it's 90 topside. (not that a dry suit year round is a BAD idea here). Wetsuits let us dive here all we want, and they cost $200-500. Drysuits are much more expensive and require special training = more $$, more time not diving, more inherent risk when diving. So, my climate here is the perfect antithesis to your 3mm logistical cap on neoprene.
Thanks, all, -tadd
For consideration here:
-Dry suit, doubles (AL or Steel), and perhaps some stages.
-diving deep or overhead.
so, my question is: How do you guys (DIR) balance your rigs at all? I have heard the comment "you gotta be able to swim up your rig" tossed around, but is this not relevant to this type of diving? Regardless of that answer, what ARE some of the rules of thumb about balancing gear consisting of so many tanks?
That's it, just what do you consider a balanced rig in such an extreme situation, because it can't be based on the same principles as single tank/REC/wetsuit diving. This is what I am curious about.
underwasser: Here in SoCal you couild go surfing in your trunks, but it's cold enough even when the water is warm to really chill you fast if you're diving. But 68 degrees is not automatically dry suit time, especially when it's 90 topside. (not that a dry suit year round is a BAD idea here). Wetsuits let us dive here all we want, and they cost $200-500. Drysuits are much more expensive and require special training = more $$, more time not diving, more inherent risk when diving. So, my climate here is the perfect antithesis to your 3mm logistical cap on neoprene.
Thanks, all, -tadd
MonkSeal
Contributor
You allways balance with back-gas tank(s) only. Deco/stages are not relevant since we use aluminum tanks (roughly neutral) that can be handed to team mate or sent up in case of need. If you are neutral at last stop with nearly empty tank(s), with no gas in wing (and drysuit) - that's it.seiff:
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