Tanks . . the good, bad and ugly

BettyRubble · Jul 27, 2009

So I had the 'pleasure' (rolling eyes) of diving with an AL80 tank this weekend instead of my favorite steel 72. Shop was out of steel 72 and 80's (only had a 120 - nearly as tall as me!).

Well it wreaked havoc on my weighting, which I was already experimenting with. Very annoying to say the least.

So, in my usual anal retentive method, I've been deep diving (no pun intended) info on tanks. Looking to buy my own by year end (maybe a Christmas present for myself!!!!) I've got a chart on the types of manufactueres and sizes and how much weight and buoyancy each alledgedly is rated for.

I'm leaning towards a steel 72 (assuming I can get my hands on one) but a recent dive buddy who is a tech diver suggested I am a bad buddy for diving it. His concern is it won't allow enough air for an OOA situation with a buddy.

So that makes me think I have to at least go with a steel 80 and probably larger.

Some background: I can dive steel 72 and come up with 1200+psi after 40-60 minute dives (usually 1500 or more). Apparently my sac rate is decent. I'm 5'2 so the longer tanks hit me in the head and arse at the same time (VERY ANNOYING) so the 72 and 80's 'fit' me much better. Finally, I have a bad back. I have to consider the weight of everything I put on me -- not just total weight, but placement -- higher is better, lower really takes its toll on me. So a steel tank helps me keep weight off my belt / bc area, and a 72 is small enough and manageable for me when lifting and carrying it.

So all this whining on my part to ask, how much consideration do I need to give this buddy OOA situation. Don't get me wrong, I don't want to jeopardize a buddy, just want to know what should go into that calculation.

And yes, I am considering going with a steel backplate/wing setup at some point. But for now, I love my Zena so a new BC setup is at least a year away.

As always, appreciate your input. Will be out of town for a week so forgive me for not responding to posts during that time.

Stu S. · Jul 27, 2009

My daughter is a bit taller than you. Uses HP80's; both Faber and Worthington. With a 3mm suit she might need a one or two pound weight. She uses a back inflate BC. No plate. A steel plate would leave a diver like her overweighted.

Faber 80's go for $199 on sale at Diver's Direct. You may want to watch their website fot a sale.

spectrum · Jul 27, 2009

If you are coming up with 1200 +PSI how much does this buddy expect you to have on hand for an OOA? Besides, the size of your cylinder is just an input for your gas planning using rock bottom or some similar method, it is not a safety trad-off if done right.

I have a regular buddy so dives steel 72s exclusively and I have never felt myself to be at risk. On top of that I have gotten a number of OOA divers to shore while diving my 72.

Get a cylinder you are comfortable with and have at it. If you are talking about those white Faber often ScubaPro branded cylinders I hear you. I have one and I love that little bugger.

Based on what I hear you saying you will be a match for many guys diving 100 CF cylinders with your 72.

Pete

Buccaneer · Jul 27, 2009

I agree with the posts above- you are coming back with plenty of air, so there is no issue there. I too would really encourage you to check out high pressure steel 80's. THey are really short and not very heavy at all. My wife also has serious lower back issues, to the point nothing can touch or bump her lower back. For her the HP80's are perfect!

D_B · Jul 27, 2009

As Spectrum said, it sounds like you have the size you need in a 72

HenrikBP · Jul 27, 2009

Here's a good read about choosing tanks in general:

How to Select a SCUBA Tank - Dive Gear Express

Also take a look at the dimensions chart for steel tanks here:

X-Series Steel SCUBA Tanks by Worthington Cylinders - Dive Gear Express

Henrik

spectrum · Jul 27, 2009

Buccaneer:
I agree with the posts above- you are coming back with plenty of air, so there is no issue there. I too would really encourage you to check out high pressure steel 80's. THey are really short and not very heavy at all. My wife also has serious lower back issues, to the point nothing can touch or bump her lower back. For her the HP80's are perfect!

The HP 80 is my typical cylinder (own 4) and I agree that it's an excellent package and would be the logical choice if BettyRubble decides she wants to carry more air. I even wrote a page about them!

Pete

NorthWoodsDiver · Jul 27, 2009

BettyRubble:
So I had the 'pleasure' (rolling eyes) of diving with an AL80 tank this weekend instead of my favorite steel 72. Shop was out of steel 72 and 80's (only had a 120 - nearly as tall as me!).

Well it wreaked havoc on my weighting, which I was already experimenting with. Very annoying to say the least.

So, in my usual anal retentive method, I've been deep diving (no pun intended) info on tanks. Looking to buy my own by year end (maybe a Christmas present for myself!!!!) I've got a chart on the types of manufactueres and sizes and how much weight and buoyancy each alledgedly is rated for.

I'm leaning towards a steel 72 (assuming I can get my hands on one) but a recent dive buddy who is a tech diver suggested I am a bad buddy for diving it. His concern is it won't allow enough air for an OOA situation with a buddy.

So that makes me think I have to at least go with a steel 80 and probably larger.

Some background: I can dive steel 72 and come up with 1200+psi after 40-60 minute dives (usually 1500 or more). Apparently my sac rate is decent. I'm 5'2 so the longer tanks hit me in the head and arse at the same time (VERY ANNOYING) so the 72 and 80's 'fit' me much better. Finally, I have a bad back. I have to consider the weight of everything I put on me -- not just total weight, but placement -- higher is better, lower really takes its toll on me. So a steel tank helps me keep weight off my belt / bc area, and a 72 is small enough and manageable for me when lifting and carrying it.

So all this whining on my part to ask, how much consideration do I need to give this buddy OOA situation. Don't get me wrong, I don't want to jeopardize a buddy, just want to know what should go into that calculation.

And yes, I am considering going with a steel backplate/wing setup at some point. But for now, I love my Zena so a new BC setup is at least a year away.

As always, appreciate your input. Will be out of town for a week so forgive me for not responding to posts during that time.

I tend to love aluminum 80's, they make ok single tanks, great sidemount bottles, good stages, etc. They are light and easy to manipulate underwater so if you get into tech diving its nice to have a few around. They are also lightweight on land which is a plus for many people.

For all around diving with backmount tanks though I would say hp100's seem to be a favorite for most people and they are not too heavy or big.

I own 4 lp72's that I got just for sidemount diving. They work well but I have since switched to diving aluminum 80's instead except for when I have my thickest undergarments on. the &2's are nice for certain uses but I can't say they are great for everything.

I overfill my 72's though so I get some more gas otta them, you may or may not be able to or interested in doing this...

If I was buying a tank tomorrow for recreational depths or with the possibility of getting into doubles I would buy a pair of hp100's. Then I would have 2 matching tanks if I should want to double them up but I could use them for backmount singles or sidemount bottles too.

Don't knock 80's though, they have a place...

BettyRubble · Jul 27, 2009

Thanks everyone for the quick and awesome replies. I'll dig into these more when I return. I doubt I'll ever be able to dive doubles except in rare cases where I can gear up in the water, so in the short term that's not under consideration.

Thanks again!!!

TSandM · Jul 28, 2009

There is a concept which is often referred to as "rock bottom", "minimum gas", or "bingo gas". This is the amount of gas that is needed to get you and buddy to the surface from the deepest portion of your dive, making all appropriate stops. It's usually calculated using fairly generous numbers for estimated consumption rate during an emergency ascent (which is probably not unrealistic, especially for newer or less frequent divers). It's a surprisingly large amount of gas -- for example, from 60 feet, the amount is 20 cubic feet, and from 100, it's 40.

Now, if you are diving a 72 cubic foot tank, that 40 cubic feet is more than half of the supply you have, so if you dive that tank to 100 fsw, you have very little time there before you have to ascend. This is the basis of the recommendation that you never dive deeper than the number of cubic feet in your tank.

I don't like to limit my bottom time or my depth to that degree, so I dive larger tanks. I'm 5'4", and I dive LP95s and HP100s as singles, and sometimes HP130s, and I don't have any trouble balancing any of those tanks. The HP100s are probably the nicest, in terms of weight for volume, and I would highly recommend them.

BTW, I think your buddy has a good point. More about this topic HERE.

Tanks . . the good, bad and ugly

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