Reasons for using aluminum tanks in cold water?

[Razorista]

...You don't even know how to rig SM tanks and why.

Then please enlighten me oh great sidemount guru
What would you recommend to improve?

This is cold water, Razor 2.1 unmodified, used and looking damaged in places, 8 kilos (could actually be 10 if I see that correctly, but I wrote it down differently by mistake as 8) of lead compared to 12 with aluminum 7Liters and 80cft.
Drysuit Whites Fusion Sport, temp 10 degrees, steel tanks 19liters, 21kg.
Pressure of around 180 bar and 150bar at that moment, just switched before the vid.
In exactly the same config I use with aluminums, not a D-ring was moved, the bungee is the same 6mm single bungee (a new one though, the old one made for aluminum and light steel tanks did not work well and was old anyway).

 

[Bennno]

You've been told by a bunch of people like 20 times:
- loops and thicker bungee, in the video you can see that your tanks wobble around like crazy
- move the clamp futher up, having the clamps too far down causes the tanks to be pushed forward
- you use way too little weight, with 19l tanks at 180 bar the wing should be huge at this point
- you spreed your legs way too wide when kicking, constantly moving the tanks to the side each time you kick
Also, it doesn't make much sense to have gauges pointing backwards, if your tanks are trimmed out properly they don't 'shovel'.

 

[Razorista]

You've been told by a bunch of people like 20 times:

As I also told you several times:

- loops and thicker bungee, in the video you can see that your tanks wobble around like crazy

Don't need them, works better for me without.

- move the clamp futher up, having the clamps too far down causes the tanks to be pushed forward

Destabilizes the tank bottom, so: no.
Especially with those tanks I want easy access to my valves and regulators.

- you use way too little weight, with 19l tanks at 180 bar the wing should be huge at this point

No, as you see it does not have to be inflated more than a few liters.
That is just 4meters of depth and I did not change anything until the tanks where empty after three dives and could still take of my fins free floating in 1m of depth.

- you spreed your legs way too wide when kicking, constantly moving the tanks to the side each time you kick

Small camera angle. as you can see I have to maneuver to stay inside and that was guesswork.

Would have been no point making the video if I did not move with body cramped, didn't shake my shoulders, twist my hips, etc...
Had to find out if it can take stresses and if the weight would lead to unexpected effects - it did not.

Also, it doesn't make much sense to have gauges pointing backwards, if your tanks are trimmed out properly they don't 'shovel'.

They do, tried that. A beginners error in my book.
They also point in the wrong direction when swinging the tanks forward.
I do not look at the SPGs more then two or three times in a normal dive, not at all often enough.
I like them protected and 'out of the way', they are not important enough to expose.

 

[Bennno]

I was going by your videos, not by that picture.

 

[Razorista]

I was going by your videos, not by that picture.

My videos are for the purpose of learning @Bennno .
Not my own learning only (but primarily).

I do not have a camera diver, I drop my cam on the ground and take a quick selfi, or give it to a buddy normally not using a camera.
I can live with not looking like a 'Steve', since that's not my name anyway.

 

[Grocio]

Steel is the rule for single and back-mounted bottles here in the Netherlands, whereas alumnium is the rule for stage bottles.

 

[decompression]

So Dan, did you get an answer to your original post?

 

[gearhound]

Hey guys,
I keep seeing people using aluminum tanks in their drysuits. It's seem to be fairly popular in Europe for some reason and youtube is full of skill and 'playing around' videos with people in drysuits/AL tanks. So, why is that? It doesn't seem to have any advantages. You can carry less gas but the tanks are larger, you need tons of weight that you have to strap right onto your spin basically. One guy I know got trained by a Razor instructor here in Germany needs 18kg/40lbs to dive his AL tanks in the Baltic Sea. He was told 'it's better'. He couldn't really say why.
I kind of suspect the reason for this is that lots of Europeans learn about sidemount either on youtube or in Mexico and therefore think you need AL for sidemounting... but I'm just guessing here. The Florida/North American-style sidemount seems to be much better for cold water diving.
Any thoughts?

I would suppose it is partly the function of price. Many people will make do with what they have on hand, at least that's what I've seen from students. After spending cash on a new bcd and regs, they hold off on spending more on tanks if they already have some on hand.
Personally I dive both steels and aluminum. I prefer the aluminums because I like the way they feel. I am much more maneuverable with aluminums. I can get into whatever position I want. I've actually been selling off my steels, keeping just a set of 85s as they're pretty light in the water.
Another major reason for me is that my favourite place to dive is the caves of Mexico. So the old saying "train how you're going to fight" applies. So even when I'm ice diving, I'm very likely to use my aluminums.
Without turning this into a Florida/Mexico thing, I can dive both steels and Alu with the same bcd. I don't need to change to thicker bungees, but don't see the issue if you have to. Seems to be a double standard, where it's okay to modify a Hollis, but not okay to modify a Razor. Once you own it, customize it to work for yourself.

 

[Patoux01]

I would suppose it is partly the function of price. Many people will make do with what they have on hand, at least that's what I've seen from students. After spending cash on a new bcd and regs, they hold off on spending more on tanks if they already have some on hand.

Here around, most people who switch to sidemount already have their own tanks, and it's usually steel.

 

[The Chairman]

I side mount LP120s in the Florida Caves. I love them, as I have 360 cf of air when they have a full cave fill. I can see some cave that way. However, they are cumbersome, even in the water. If I remove one tank completely and vent all of the air in my LTZ, I am about neutral, but just a tad light. I could pass it off to a diver in need, but then, they might be too heavy. I don't enjoy un-clipping my tanks, either or both, and putting them in front as it greatly influences trim. LP85s are easier in this respect, but they only give me 250 cf on a cave fill.

When I side mount AL80s in the Mexican Cenotes, I have to add weight to get neutral. I do put 3 pounds on the bottoms of each tank as I don't like how the butt changes buoyancy through the dive. Anyway, I could pass off a tank easily and it not greatly affect my buoyancy or trim. I could probably lose both tanks and breathe myself neutral, making no-mount possible. Un-clipping tanks, either or both, and putting them in front is a cinch and trim remains rather easy to maintain. Yes, they are normally shallower than the Florida caves, but I find 160 cf to be overly constrictive. That's far less than half of my cave filled LP120s.

The solution for me is going to be a rebreather. The SF2 is about the best thought out side mountable rebreather out there, in my most humble opinion. I'm getting mine next week.