Weight ideas for an AL 80 Stage Bottle.

[TrimixToo]

@Rusty Shackleford what was said above is true. If you're following a line, just clip it to the line *what we do in caves*. If not, you really don't want to drop it unless it is at a distinct location. In that case, I'd use a 4lb clip weight that you clip to yourself, then clip the tank to it. You don't want it to to be negative the whole time, that would be really annoying and you may as well just find a LP72 and use it instead of dealing with lead but there's a reason we don't use them.
That all said, scootering with an empty AL80 is not a big deal especially if you put a bungee loop on the side of your backplate sidemount the bottle instead of letting it hang like the standard DIR setup which I can't stand. If you're really annoyed with it being sidemounted, well there are options.

In this video you can see how you "nose clip" a stage which is really just using the top clip and clipping it to your left hip d-ring. This is easy, unobtrusive, and when you're on the trigger, the tail will drop down in the slip stream. You can also use a leash to put it between your legs. Typically only done when you have multiple stages, but if you really want it off of the normal loaded position, then it's the best way
and how to make a leash

What is the reason you don't use LP72s?

 

[tursiops]

Split the difference. Don't breath it down to empty, treat it like a stage and just breath it down to 2000 (use one-third). Drop it, it will be almost neutral. Pick it up on the way back and breath another third. At 1000 it will be about 2 lbs buoyant, easy to handle with one hand.

 

[tbone1004]

@TrimixToo too heavy when full and cause to you roll when loaded on one side or pitch feet down if butt clipped.

 

[TrimixToo]

@TrimixToo too heavy when full and cause to you roll when loaded on one side or pitch feet down if butt clipped.

I thought I had a chart that included LP72s along with other scuba cylinders somewhere, but I can't seem to find it in my files or online. But a search here shows Post #4 in this thread: Specs on the old 72cf steel tanks?

...which includes this info:

72 cu ft Standard

Service pressure, psi : 2250
Actual air capacity, ft3 (at 2475 psi): 71.55
Outer diameter, in: 6.81
Length without valve, in: 25.12
Empty weight, lbs (w/o valve): 26
Buoyancy Empty, lbs (w/valve): 0
Buoyancy Full, lbs (w/valve): -5.4

vs. Catalina S80s at +4.1/-1.6 and Luxfer S080s which are close to the same.

I don't seem to have that big a problem with rolling to the side when I clip one off, though if I don't need two deco gases I'm likely to be using something smaller than a 72 (LP45); and, I'm of course as balanced (or otherwise) with two LP steel tanks as I'd be with AL80s.

Is it accurate to say you prefer light and floaty when empty to a bit heavier when full? Or is it that you prefer more weight to more buoyancy when you have stages/deco bottles attached? I haven't looked closely at the difference in streamlining, but the larger AL80s' diameter offsets some or all of the drag from more air (somewhere, wing or suit) to balance out the slightly heavier tanks. (8 lbs difference calls for 1/8 cu ft of additional air in salt water...probably not much change in frontal area.)

I am not trying to argue, just to understand. You are not the first to suggest that AL80s are better. I am happy to rethink what I have been using, if I should. I wound up with LP tanks overall because my K14-85 compressor before upgrades was rated at 3200 PSI. To convert stages and deco tanks to aluminum, I'd need to get tumbling media for AL and become happy with pumping higher pressures of O2, at a minimum.

 

[tbone1004]

@TrimixToo much prefer light and floaty. It also means you don't have to have extra lift on your wing which when cave diving is usually not possible. My bcd in doubles or sidemount is usually damned near full. At times my buddies have been very grumpy with me because when we've been diving my sidemount rig was truly full and as we ascended they would start screaming as they vented which is admittedly quite annoying. That particular dive was with a wetsuit and LP120's, and when dry it's never quite that full, but it's certainly full enough that if I had LP72's instead of AL80's as deco or stage bottles, I wouldn't have had 4lbs of lift per bottle in reserve. 4lbs/bottle adds up pretty quick when you're in thin undergarments with massive backgas bottles.
They also don't float when empty, so when you have multiple bottles on a leash behind you it will throw your pitch off which is really difficult. AL80's when full are noticeable when nose clipped and a LP72 wouldn't work.
I love LP72's, I have many of them, but for the diving I do the AL80's are much better from a buoyancy perspective.

 

[TrimixToo]

@TrimixToo much prefer light and floaty. It also means you don't have to have extra lift on your wing which when cave diving is usually not possible. My bcd in doubles or sidemount is usually damned near full. At times my buddies have been very grumpy with me because when we've been diving my sidemount rig was truly full and as we ascended they would start screaming as they vented which is admittedly quite annoying. That particular dive was with a wetsuit and LP120's, and when dry it's never quite that full, but it's certainly full enough that if I had LP72's instead of AL80's as deco or stage bottles, I wouldn't have had 4lbs of lift per bottle in reserve. 4lbs/bottle adds up pretty quick when you're in thin undergarments with massive backgas bottles.
They also don't float when empty, so when you have multiple bottles on a leash behind you it will throw your pitch off which is really difficult. AL80's when full are noticeable when nose clipped and a LP72 wouldn't work.
I love LP72's, I have many of them, but for the diving I do the AL80's are much better from a buoyancy perspective.

Interesting. I'd like to do cave someday. It sounds as though I'll have to buy or rent some 80's then. For wrecks, I stage my deco tanks near (never on!) the upline or just outside the entry as a rule.

Here where the water is colder and sane people wear more insulation, I have no remaining air to vent from my wing at 10' with two LP72 deco bottles and a third of my back gas. If the LP72s (or, heaven forfend, the back gas tanks) are empty or nearly so I need to fully vent my suit to stay neutral (not a terrible thing this time of year) unless I add some weight...so maybe this is an environmental thing.

 

[Rusty Shackleford]

Split the difference. Don't breath it down to empty, treat it like a stage and just breath it down to 2000 (use one-third). Drop it, it will be almost neutral. Pick it up on the way back and breath another third. At 1000 it will be about 2 lbs buoyant, easy to handle with one hand.

Actually, this occurred to me as the best solution. Great minds think alike.

I know I am not going to breath it near-empty again and try and handle it. If I am sucking it low, it’s on to stay for the rest of the dive.

I wanted to see what it was like switching sides. Admittedly, it was an extreme test. Wanted to get a feel for the bottle and for my new stage reg set-up, the Deep 6 sig second and the MK-2 first combo.