What tank is right for me?

[1KaJ]

Long time lurker, first post. First, a little information about me:
-Been diving since 2008
-I am 28 years old, 6'1", and around 210lbs
-28 years old
-Been using AL80s for over 100 dives, mix of tropical (rash guard only) and cold water (full 7mm wetsuit) recreational dives
-Max depth 120ft, max dive time was 80 minutes (using an AL100 tank)

Last week I went on 10 dives in Cozumel and used an AL100 tank for the first time. I went diving with a lady friend of mine who is 5'1" and I still cut our dives "short" even though I used an AL100 and she used an AL80. I say "short" meaning she came up with 1100psi left while I only had 600psi. We still had an average dive time of 60 minutes.

When diving with the AL100, I needed 12lbs to slowly decend while exhaling and barely needed to touch my BC during the dives (had to dump air every 10 mins or so). By the end of the dive I would be neutral at our 3 min safety stops. The only complaint I had with the AL100 was it was pretty heavy before the dive and sometimes my feet would hit the bottom of the tank while maneuvering through tight corners underwater.

I have always been told that steel tanks may suit me better, I could drop around 4-5 lbs and have a lot more air. This way my buddy and I could both surface with ~600psi in our tanks instead of me cutting it short. I have been looking at the XS Worthington tanks: AL119, 120, or 130. I am concerned that the AL120 may be too long (although shorter than an AL100). I am also worried about not feeling trim and feeling heavy towards my head, (moving the weight from my belt to the tank). So I guess the question is pretty basic, which tank should I buy? It will be used for both boat and shore dives and mainly off the coast of California.

 

[MXGratefulDiver]

It's a highly personalized decision, and without seeing how you trim out in the specific cylinders, it's hard to say. I have been working with a guy for a couple years who had been diving the steel 120's and never could get his feet up ... it's a long, very negative tank and you need the levers to trim it. You're a bit taller than him, but I will tell you that when I put him on shorter 100's or 119's his problem improved immediately and dramatically. He recently purchased HP100's and sold the 120's.

My suggestion is if you have the opportunity, try diving them all and choose the one that feels the most comfortable with the other equipment you're currently using. A big part of air consumption comes from being able to relax during your dive, rather than having to constantly fight to stay in trim. Sometimes you can resolve that by moving weights, but sometimes it just boils down to having gear that fits you well ... and that includes your tank.

FWIW - doing a dive to 120 for 80 minutes on an AL100 is pretty darn good ... that doesn't sound like an air hog to me at all ...

... Bob (Grateful Diver)

 

[1KaJ]

It's a highly personalized decision, and without seeing how you trim out in the specific cylinders, it's hard to say. I have been working with a guy for a couple years who had been diving the steel 120's and never could get his feet up ... it's a long, very negative tank and you need the levers to trim it. You're a bit taller than him, but I will tell you that when I put him on shorter 100's or 119's his problem improved immediately and dramatically. He recently purchased HP100's and sold the 120's.

My suggestion is if you have the opportunity, try diving them all and choose the one that feels the most comfortable with the other equipment you're currently using. A big part of air consumption comes from being able to relax during your dive, rather than having to constantly fight to stay in trim. Sometimes you can resolve that by moving weights, but sometimes it just boils down to having gear that fits you well ... and that includes your tank.

FWIW - doing a dive to 120 for 80 minutes on an AL100 is pretty darn good ... that doesn't sound like an air hog to me at all ...

... Bob (Grateful Diver)

The max depth was 120, but I was only there for a few minutes. The average depth was 40-50ft, plus I didn't need to kick much at all, just let the current take me. I am definitely better on air than most of my other buddies who I dive with, but not so much when compared to my lady friend (who I dive with the most). I was leaning towards the 130 so I could get 2 short dives out of it when I take my newly certified friends out later this month (they only last 30-40 min). Thanks for your input.

 

[freewillie]

There are two separate answers to your question.

The first is that bottom time is dependent upon your SAC rate and multiple factors go into how long and how quickly you go through your air. A smaller person has smaller lung volumes and will typically use less air breath per breath than a larger person. Just plain physics which you can't change. Then you factor in things like trim, efficiency, overall health, etc. I'm assuming your bottom time 80 minutes wasn't at max depth of 120 ft. either. I've never been into double or decompression diving but even without looking at a dive table that would be highly unlikely on an AL 100.

Steel tanks have the advantage that you redistribute the weight from your weight belt (or integrated BC) to the tank. The total weight is the same, except you have moved some of it directly to the tank and not on your belt. So, steel tanks are heavier which you have experienced already. They are also less buoyant when empty so you don't have to add the extra weight for the end of the dive.

The other thing you haven't mentioned is if you're planning on getting high pressure versus low pressure steel tanks. The size of the tank will vary and you can get the same volume of air in a smaller tank by increasing the pressure, hence a high pressure tank. You mentioned the aluminum tanks but they will also have the same volume but at lower pressures so their size will be larger relative to a low pressure steel but the LP steel is going to be larger than a high pressure steel. If you are concerned about the length of the AL tanks you should look into either LP or HP steels.

 

[WB2GLP]

I would go with HP 120s. I have a bunch of older PST HP 120s and rarely use anything else for local diving.

 

[lamarpaulski]

The Cozumel diving experience with a small female buddy should not inform your decision to buy a tank you will use in California, especially for shore diving. Why not steel ? How do you do with Al 80 in California ? Try renting or borrowing some different tanks for your usual cold water diving. How do you walk with tank on your back ? Etc...

Long time lurker, first post. First, a little information about me:
-Been diving since 2008
-I am 28 years old, 6'1", and around 210lbs
-28 years old
-Been using AL80s for over 100 dives, mix of tropical (rash guard only) and cold water (full 7mm wetsuit) recreational dives
-Max depth 120ft, max dive time was 80 minutes (using an AL100 tank)

Last week I went on 10 dives in Cozumel and used an AL100 tank for the first time. I went diving with a lady friend of mine who is 5'1" and I still cut our dives "short" even though I used an AL100 and she used an AL80. I say "short" meaning she came up with 1100psi left while I only had 600psi. We still had an average dive time of 60 minutes.

When diving with the AL100, I needed 12lbs to slowly decend while exhaling and barely needed to touch my BC during the dives (had to dump air every 10 mins or so). By the end of the dive I would be neutral at our 3 min safety stops. The only complaint I had with the AL100 was it was pretty heavy before the dive and sometimes my feet would hit the bottom of the tank while maneuvering through tight corners underwater.

I have always been told that steel tanks may suit me better, I could drop around 4-5 lbs and have a lot more air. This way my buddy and I could both surface with ~600psi in our tanks instead of me cutting it short. I have been looking at the XS Worthington tanks: AL119, 120, or 130. I am concerned that the AL120 may be too long (although shorter than an AL100). I am also worried about not feeling trim and feeling heavy towards my head, (moving the weight from my belt to the tank). So I guess the question is pretty basic, which tank should I buy? It will be used for both boat and shore dives and mainly off the coast of California.

 

[scubadada]

Hi 1KaJ,

If you knew your and your friend's SRMV, you could pretty easily figure out how much gas you need to match her consumption when she's using an AL80 (77.4). Quick and dirty based on the dive stats you gave, I'm estimating her SMRV at a little over 0.3 and yours at a little over 0.5 cu ft/min. You'd be well matched if you were diving a 119 or 120 and would come up with nearly the same reserve volume.

I like the steel tanks better also but the larger ones can be long and/or heavy. I dive a steel 100 much of the time. My SRMV is mid 0.3s, I get plenty of time.

Cylinder	Service Pressure (psi)	Diameter (inches)	Height (inches)	Weight Empty (pounds)	Buoyancy Full : Empty (pounds)
X7 Steel 65	3442	7.25	16.7	25.1	- 8.7 : - 3.9
X7 Steel 80	3442	7.25	19.8	29.9	- 9.0 : - 3.0
X7 Steel 100	3442	7.25	22.7	33.1	- 10.0 : - 2.5
X7 Steel 120	3442	7.25	27.7	39.7	- 11.0 : - 2.0
X8 Steel 119	3442	8.00	23.9	42.5	- 10.9 : - 2.0
X8 Steel 130	3442	8.00	25.3	44.7	- 11.7 : - 2.0

Comparison Only - Aluminum 80

3000

7.25

26.1

31.9

- 1.8 : + 3.2

 

[CAPTAIN SINBAD]

I am 5.10 and my tank of choice for over all diving is a steel 100. I have used an HP 130 and would not mind using it for deeper dives. In shore diving it may be too much to drag around. Steel 100 also trims out the best on me.

 

[DBF]

The advice given to me when purchasing a tank is to look at the physical size and weight firstly. Too big and heavy and you are exhausted before getting wet, too small and weight distribution is a problem when in the water.

Never worry that your buddy has too much gas left.

Plan and dive the gas you have.


There is no magic size.

Steel or AL is managed by lead if it the right physical size.


Sent from my iPhone using Tapatalk

 

[fnfalman]

A steel 100 has no more air in it than an aluminum 100

If you're a guy of reasonable good health, and by the end of a 60-minutes recreational multi-level dive with a 100-CUFT tank and you only have 600-psi left, then you should work on your techniques so that you'd slow down your air consumption. Slinging a bigger tank is a temporary solution. If you think the AL100/steel 100 are heavy, try carrying a steel 120 or 130. Those things are beasts.