Stage bottle types Al or steel

[Captain Ron]

I was informened that the Steel LP 65s that I was planning on using may not be the best choice. I was told by someone that I trust that the neg. boyancy of the steel tanks can cause problems and that AL tanks are better for stage. Please explain.
See: Size of doubles thread.
Thanks

 

[Hyper-limits]

I was informened that the Steel LP 65s that I was planning on using may not be the best choice. I was told by someone that I trust that the neg. boyancy of the steel tanks can cause problems and that AL tanks are better for stage. Please explain.
See: Size of doubles thread.
Thanks

Aluminum 40 would be the ideal deco cylinder. Steel of course will be negative
and will make you roll to the side it's secure to. If you need more deco gas Al 80 would be the next size to go to. With an Aluminum 40 you should be good for 30 minutes of deco.

Cheers
AL

 

[Doc Intrepid]

I was told by someone that I trust that the neg. boyancy of the steel tanks can cause problems and that AL tanks are better for stage. Please explain.

Ron,

Many believe that aluminum Luxfer tanks make excellent deco tanks, due to their bouyancy characteristics. Steel tanks hang low off the diver, like a keel, being inherently negative - often when empty as well. Aluminum tanks (there are variances between Luxfer and Catalina, although there are debates as to whether the variances are negligible or not) are butt light, and tend to ride on the diver's sides with the butt end up in the slipstream of the diver's shoulders, aiding in streamlining and cleaner profile. If need be, you can move the neck boltsnap down to the left waist D-ring on an empty cylinder, and the butt will ride up and behind the diver tucked in next to the doubles. This will not occur with a steel tank. On a longer deco dive, it is possible to send empty aluminum cylinders up on a line - when 'empty' just clip to the line, they'll float up. This cannot be done with steel tanks. In short its the 'swing weight', or the shift from roughly 3 lbs negative to roughly 2-3 lbs positive that occurs with Luxfer aluminum 40s and 80s, and how this consequently lets them ride clipped to the diver, that causes them to be considered optimal deco tanks.

Hope that helps.

Doc

 

[DA Aquamaster]

Steel tanks when used as deco bottles can leave the diver excessively heavy.

An 80AL is also perhaps overkill unless you are going very deep and are going to incur a lot of deco. In most cases one or two AL 30's or AL 40's will do the job nicely.

An advantage of carrying two AL40's over one AL 80 is that you could carry nitrox 50 in one and Nitrox 80 or pure O2 in the other and do a better job of optimizing the deco. Another advantage is that the AL 30's and AL40's are much smaller in diameter and are less obtrusive during the dive. I would not carry a deco tank larger than AL 40 unless I absolutely had to.

 

[Diver0001]

I was informened that the Steel LP 65s that I was planning on using may not be the best choice. I was told by someone that I trust that the neg. boyancy of the steel tanks can cause problems and that AL tanks are better for stage. Please explain.
See: Size of doubles thread.
Thanks

Around here aluminium tanks are rare, difficult to get hydro'd and "unfamiliar" (not to mention large for the amount of gas they store) so a lot of divers use *small* steel tanks as pony's and deco bottles and it all works. For example, I have a small 5 litre 300 bar stage (that's maybe 48cf for you) that is decidedly not-dir but works for the particular application I have it for (up to 1/2 hour of deco at 6 metres).

To get around the problems that Doc INtrepid mentioned you may need to play around with just how you hang the bottle on your gear but as long as the negative buoyancy is limited to couple of kilos you can "get away with it".

If you're talking stages for deep diving then that's out of my ball park and I'll refer you to the experts.

R..

 

[kramynot2000]

My last few times up at Lake Tahoe I used two AL80's each dive because it held enough deco gas for a weekend of diving without having to get a fill in between days, which can be hard to find up there. I would have preferred to use AL40's but I only have two. What I found was that after the initial adjustment to having such big tanks, I forgot they were even there. We were diving off a small boat so we put the AL80's in the water, rolled off the boat and then donned them while we were in the water. Worked real well. On the second day the AL80's just floated up and out of the way because they were low.

Biggest benefit was that the next time I used an AL40, it felt like nothing.

 

[Captain Ron]

Looks like I'll be cleaning a couple of my Al 80's and picking up a couple of 40's. I'll be back with more questions after I get back from the dive store. Don't tell my wife were I'm going.LOL

 

[ScubaDadMiami]

It's all been said above. Steel was in about 10 years ago for deco bottles. I bought aluminum 40s and have continued with them ever since.

Now if only the rest of the world will catch up to me without having to wait ten years concerning fixed d-rings, multiple bottom timers and lift bags.

 

[NEWreckDiver]

Well, I use steel 50's for most of my dives and have never had any issues with being overweighed or in the way the bottle hangs. I don't suffer from the buoyancy shift that the aluminum tanks have either.

The steel tanks are smaller for the equivalent aluminum tanks. And why would one want to send a tank up the anchor line? I am sure there must be a reason. It is not a practice that we use here.

Which ever choice you make, you will need to adjust your weight for both.

Good luck and safe diving.

 

[ScubaDadMiami]

And why would one want to send a tank up the anchor line? I am sure there must be a reason.

One usually sends tanks up the line when carrying larger tanks such as 80 cubic foot stages that are used up. Less hassle than dragging them around for the rest of the dive.