Aluminum vs steel tanks

General banter about diving and why we love it.
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LCF
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Re: Aluminum vs steel tanks

Post by LCF »

Scubanewb, the fact is that there is a LOT to know about diving . . . the more fascinated you get with it, the more you explore, the more you learn.

I'm sorry that you feel that posts here are over your head, and even sorrier that you didn't feel this was a friendly enough place that you could ask questions about anything you didn't understand. I hope that someday, you get to the point where discussions of tank materials, buoyancy characteristics, and gas reserves don't come across as "blah, blah, blah", because these really ARE important things to consider when choosing tanks, or to know about the tanks you choose.

There is nothing intrinsically wrong with Al80s. They are relatively small tanks (so the person owning them needs to understand the dives ought to stay shallow) and they are physically heavy for their capacity (so not good for someone who is trying to minimize tank weight) and require additional lead to sink them (so not good for someone who is trying to minimize on-land weight). They also have a fairly pronounced change in the way they balance as they empty, which usually isn't an issue around here because of the sheer amount of lead we wear, but it can make trim at the end of a dive a little more difficult.

I think I can promise you that, 90% or more of the time, nobody here is trying to talk down to anyone, or make them feel uncomfortable or inadequate. We just have a lot of divers here with a lot of time in the water, and a lot of information. Maybe we spew it too enthusiastically at times . . .
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CaptnJack
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Re: Aluminum vs steel tanks

Post by CaptnJack »

LCF wrote: There is nothing intrinsically wrong with Al80s. They are relatively small tanks (so the person owning them needs to understand the dives ought to stay shallow) and they are physically heavy for their capacity (so not good for someone who is trying to minimize tank weight) and require additional lead to sink them (so not good for someone who is trying to minimize on-land weight). They also have a fairly pronounced change in the way they balance as they empty, which usually isn't an issue around here because of the sheer amount of lead we wear, but it can make trim at the end of a dive a little more difficult.
The only thing on the other side of this teeter totter IMO is that they are cheap and readily available.

I hate buying something to discover in short order that its suboptimal. So once the initial satisfaction of getting some budget tanks wears off and you have 50 or 100 dives on the Al80s to reinforce their shortcomings most (not all) people end up feeling like they should have just ponied up the extra money for steel tanks in the first place. Or scrounged and waited to pounce on some used steels a little longer. I think an even most annoying situation is having 1 of each and constantly messing with your weights to switch between dives.
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ArcticDiver
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Re: Aluminum vs steel tanks

Post by ArcticDiver »

One of the reasons I really like this board, especially during this, I hope, rehab time, is that once a thread starts not even God knows where it is going to go. The only sure thing, most of the time, is that within all the babble there will be kernals of worthwhile information.

One of the non-reasons, to me, of not choosing AL80 cylinders is to take weight off your body during surface periods. Weight is weight is weight is weight. When a diver is on the boat or the beach it doesn't much matter where the weight is. Whether it is in a weight harness or in a cylinder it is still weight that has to be carried and managed.

That said matters of breathing gas quantity, trim, balance, convenience and others may make steel cylinders more attractive. If memory serves me right one of the operators I've dived with on a trip used 100cf aluminum cylinders exclusively. So, there are three factors involved; gas volume needed and trim management. To me they need to be addressed separately.

Of course if the diver gets cold, or has to pee, or any number of other things having a limited gas supply is no big deal.

One modifier is what I call the Peer Effect. IF you dive with the same people essentially all the time there may be a real value to matching kit. If everyone uses the same stuff, located in the same place it probably is better. But, that is a discussion for another thread, if anyone really wants to use up more server space on a subject that must have already consumed terrabytes.
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CaptnJack
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Re: Aluminum vs steel tanks

Post by CaptnJack »

ArcticDiver wrote:If memory serves me right one of the operators I've dived with on a trip used 100cf aluminum cylinders exclusively.
AL100s are dreadfully bouyant tanks.
Sounder wrote:Under normal circumstances, I would never tell another man how to shave his balls... but this device should not be kept secret.
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Norris
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Re: Aluminum vs steel tanks

Post by Norris »

CaptnJack wrote:
ArcticDiver wrote:If memory serves me right one of the operators I've dived with on a trip used 100cf aluminum cylinders exclusively.
AL100s are dreadfully bouyant tanks.
+1 had one of those....first tank I ever bought.

Oh yeah and for the record...Steel tanks

I really had to start this sport out on a TIGHT budget which I am still on. Penny pinching all the way. Bought the first BC that came my way and the first tanks and whatever else. My main objective was to get in the water NOW. Dive always, and have fun. Mission accomplished! Did I lose a little money when selling my older gear to someone else after getting what I wanted? yeah a little, but what a great feeling to know that I made diving affordable for that person. Also I borrowed tanks and dove AL80's for a bit while I scanned CL all day. Tanks come up all the time, you just have to be quick and have money in hand.
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scubnewb
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Re: Aluminum vs steel tanks

Post by scubnewb »

Right now I am working on a deal to pick up 3 Steel 80's (2 LP 1 HP) for about $150/175 bucks. Its a "Steel" of a deal lol...

Norris wrote:
CaptnJack wrote:
ArcticDiver wrote:If memory serves me right one of the operators I've dived with on a trip used 100cf aluminum cylinders exclusively.
AL100s are dreadfully bouyant tanks.
+1 had one of those....first tank I ever bought.

Oh yeah and for the record...Steel tanks

I really had to start this sport out on a TIGHT budget which I am still on. Penny pinching all the way. Bought the first BC that came my way and the first tanks and whatever else. My main objective was to get in the water NOW. Dive always, and have fun. Mission accomplished! Did I lose a little money when selling my older gear to someone else after getting what I wanted? yeah a little, but what a great feeling to know that I made diving affordable for that person. Also I borrowed tanks and dove AL80's for a bit while I scanned CL all day. Tanks come up all the time, you just have to be quick and have money in hand.
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ArcticDiver
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Re: Aluminum vs steel tanks

Post by ArcticDiver »

CaptnJack wrote:
ArcticDiver wrote:If memory serves me right one of the operators I've dived with on a trip used 100cf aluminum cylinders exclusively.
AL100s are dreadfully bouyant tanks.
"dreadfully"? Guess that is a matter of opinion. Actually, in the application I was using them having all my weight ditchable while retaining my breathing gas was very desirable. Cylinder selection depends a lot on what you are doing. But, if a person is on a limited budget and is not a long lost into the sport afficianado AL80s make a lot of sense. There are times when perfection is the only standard. Most of the time in recreational diving, what almost all of us do regardless of what we call it, good enough is often the acceptable outcome.
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CaptnJack
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Re: Aluminum vs steel tanks

Post by CaptnJack »

ArcticDiver wrote:
CaptnJack wrote:
ArcticDiver wrote:If memory serves me right one of the operators I've dived with on a trip used 100cf aluminum cylinders exclusively.
AL100s are dreadfully bouyant tanks.
"dreadfully"? Guess that is a matter of opinion. Actually, in the application I was using them having all my weight ditchable while retaining my breathing gas was very desirable. Cylinder selection depends a lot on what you are doing. But, if a person is on a limited budget and is not a long lost into the sport afficianado AL80s make a lot of sense. There are times when perfection is the only standard. Most of the time in recreational diving, what almost all of us do regardless of what we call it, good enough is often the acceptable outcome.
All of your weight ditchable? Really why would you want that? Ditch 5lbs and you'll be at the surface pronto whether you like it or not. Its not hard to swim up a full steel tank anyway...
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fnerg
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Re: Aluminum vs steel tanks

Post by fnerg »

I'll just say that I recently used about 35 cu. ft. of air, sharing with someone else, getting back up from 90 feet. That's almost half an al80!
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Nwbrewer
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Re: Aluminum vs steel tanks

Post by Nwbrewer »

fnerg wrote:I'll just say that I recently used about 35 cu. ft. of air, sharing with someone else, getting back up from 90 feet. That's almost half an al80!
Hey, RB gas planning works!

1 minute @ 90
3 minutes between 90 and 30
3 minutes 30 to surface
7 minutes total

Average depth ~50fsw, call it 2.5 ata's for easy calculation

Stressed diver RMV - 1cu/min * 2 divers = 2cu/min

2cu/min * 7 minutes = 14cu @ 1ATA

14cu * 2.5ata = 35cu required.

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ArcticDiver
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Re: Aluminum vs steel tanks

Post by ArcticDiver »

CaptnJack wrote:
ArcticDiver wrote:
CaptnJack wrote:
ArcticDiver wrote:If memory serves me right one of the operators I've dived with on a trip used 100cf aluminum cylinders exclusively.
AL100s are dreadfully bouyant tanks.
"dreadfully"? Guess that is a matter of opinion. Actually, in the application I was using them having all my weight ditchable while retaining my breathing gas was very desirable. Cylinder selection depends a lot on what you are doing. But, if a person is on a limited budget and is not a long lost into the sport afficianado AL80s make a lot of sense. There are times when perfection is the only standard. Most of the time in recreational diving, what almost all of us do regardless of what we call it, good enough is often the acceptable outcome.
All of your weight ditchable? Really why would you want that? Ditch 5lbs and you'll be at the surface pronto whether you like it or not. Its not hard to swim up a full steel tank anyway...
The trip I am thinking of was in 6'-9' seas off a boat. I thought it would be nice to be really buoyant while riding and waiting for the boat. Math be darned. Everything would go if I needed to insure buoyancy.

It isn't even that hard to swim up double steel 100s or 120s. When you get to the surface you should have some plan on what to ditch to stay there. Me, I'd like to ditch the cheap stuff, lead, instead of lights and other kit that costs money.

'course if I don't get my body to cooperate faster I'm going to need lessons all over again and I might change my mind and start thinking like you. :angelblue:
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Re: Aluminum vs steel tanks

Post by straitscuba »

I have two AL80's that are loaner tanks. It is the bouyancy thing that keeps me from ever really using them. I will use them if all of my other tanks are empty and I have to work but I hate shifting weight to use them. I dive steel 72cf's most of the time but I also have steel HP65's, steel LP80's and steel HP119's. The 119s are set up for nitrox. I have a buddy that has two of the AL100's that bought them because they were cheap but doesn't like diving them.

Looking at the rate of deterioration of the AL tanks next to the steel tanks (I have one steel 72 that the first hydro date was 1962 and one that I believe is even older) the steel tanks seem to hold up MUCH better overall than the AL tanks. All but one of my steel tanks is galvinized and they are in great shape.
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