Aluminum 80s versus larger steel tanks

[MMM]

Ummmm MMM - I think you missed the joke here - nothing unfriendly - just banter understood by both parties

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A ScubaBoard Staff Message...

Maybe you missed the "Heh" part right at the beginning. Translated from Canadian to American that becomes Ha Ha. We tend to be a bit low key or understated. Sorry that you didn't get my joke or attempt at humor.

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[Christi]

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A ScubaBoard Staff Message...

Maybe you missed the "Heh" part right at the beginning. Translated from Canadian to American that becomes Ha Ha. We tend to be a bit low key or understated. Sorry that you didn't get my joke or attempt at humor.

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It's so official when it's in a Mod box - lol

 

[OkByMe]

I have read through the pertinent comments on the original subject, tried to ignore the comments that were not, and I don't know why there was much comment at all. Go back... way back when the low pressure 72's were the big tanks of the day. When the Aluminum 3000psi tanks came out I was all over it. Sold my 72's while I could still get some good money for them and bunched up AL 65 and 80's. Longer dive times - period. So when the high pressure steel came out in larger capacity, I was all over it again and coupled with the added O2, much, much longer dive times. I even have a 133 for backmount and busted up the doubled 85's for side mounting with it when I REALLY want some dive time and plenty of gas. I don't care about SAC, don't care about RMV, don't care about workload, don't care about weight. When all I want is gas, contingency and trim. What is the fuss? If there were a 200 in a manageable size at a reasonable pressure... I would buy that too.

 

[NAM001]

The idea is that you are exiting with less than 500-700 because of a faulty spg. Every one of my AI computers eventually read 2-300 high and had to send them in for repair. Any gage is teh least accurate at the extreems that means 0-500 has the highest probibility of bad reading. A 10% error in the low end of a pressure sensor means that 500-700 could actually be 200-400 psi. And you need 150 to supply the secondary reg stage.

In clear warm water drift dive with high visibility, with a SMB AND a boat captain you personally trust, why would you exit with 500-700 PSI? Gary

 

[Mike]

Dear Mike and CV Chief, can't we just make up? I like you both, and even Mossman a little! I hereby openly admit that some people don't like HP Steel Tanks End of story?

Dave

Done.

Now all I want to know Dave is when are you going to start offering some dives using steel 120 doubles?

 

[Dave Dillehay]

We only do that for divers who are super hoovers. I heard you were bad but not yet in that category! Grin!

Dave

 

[Ron Lee]

We only do that for divers who are super hoovers. I heard you were bad but not yet in that category! Grin!

Dave

Make him dive at 20 feet like I do.

 

[gopbroek]

The idea is that you are exiting with less than 500-700 because of a faulty spg. Every one of my AI computers eventually read 2-300 high and had to send them in for repair. Any gage is teh least accurate at the extreems that means 0-500 has the highest probibility of bad reading. A 10% error in the low end of a pressure sensor means that 500-700 could actually be 200-400 psi. And you need 150 to supply the secondary reg stage.

I use a SPG and an AI and cross check them on a tail out to around 50 PSIG about every 30 dives for that very reason. With an IP gauge you can find your IP set point, as you cross that point you can feel the regulator pull differently, this gives a reference / cal point and in benign conditions you can do a poor man's calibration cross check. As you drop below this rate the 2 gauges should match, if not go with the lower reading gauge and visit the repair / bench check facility, to verify calibration. Do not suck the bottle dry as this may cause the operator to pay for a cleaning.

 

[Dirty-Dog]

I too typically agree with the larger tnaks being used as a crutch - for SOME divers.

However, I find that I can get the same bottom time with an AL 80 as I get with the steel 100's - in FACT, I get BETTER bottom time on my 80's than I do on a steel 100. This past "low season" - we did alot of "fun" diving to pass the time - we as in fellow dive shop owners - some days on their boat with their tanks, some days on my boat with my tanks. I consistently got the same or better bottom time with my 80's than with the steel 100's - and for me personally, I am much more comfortable with the AL tanks vs. the steel tanks which roll me! Of course each person is entitled to have their own preference and knows what works best for THEM.

Everyone has their preferences, but I do get tired of the argument that the steel tanks give significantly more bottom time - if you are a skilled diver and can properly manage your air - then you can get PLENTY of bottom time (70 - 90 minutes) from an AL tank.

I'm confused. Can you explain to me how I can "manage" my air in such a way as to alter human physiology?
I'm not the most experienced diver, with a bit over 200 logged dives. But I do know a fair bit about human physiology (sort of a job requirement, you know). It takes more to power my body than it does yours. I know this, because we've met, and you are considerably smaller than me.
I absolutely will not get 70-90 minutes bottom time from an AL80 on a typical Cozumel dive.


Sent from an old fashioned 300 baud acoustic modem by whistling into the handset. Really.

 

[Skittl1321]

I'm confused. Can you explain to me how I can "manage" my air in such a way as to alter human physiology?
I'm not the most experienced diver, with a bit over 200 logged dives. But I do know a fair bit about human physiology (sort of a job requirement, you know). It takes more to power my body than it does yours. I know this, because we've met, and you are considerably smaller than me.
I absolutely will not get 70-90 minutes bottom time from an AL80 on a typical Cozumel dive.

CVChief is quite a bit larger than I am (I'm 5'0" and a pretty normal weight) and he uses way less air than me- probably got 15-20 minutes more in most cases, diving about the about the same profile (he did tend to go deeper than I did, and probably used more energy taking photos, which would lead to him using more air, not less).
Out breathing a divemaster with thousands of dives is going to be tough- but size is really not the only factor. We had a DM in our OW class who was a BIG guy- clearly overweight, big guy. He said he had better air management than the other DM, who was a very fit guy with similar experience level.

Christi wasn't just saying SHE gets 70-90 minutes, but that her customers do. (90 does seem long to me for a 'typical' dive; but what is 'typical'? I'm guessing that 90 minutes is a shallow dive, but shallow dives like Columbia Shallows, Paradise Reef, or similar aren't uncommon for second dives, so that could be typical.)