Aluminum 80s versus larger steel tanks

[Christi]

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.

 

[shardison]

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.

Well, I guess I need to keep practicing... I'm 10-20 minutes short of that.... I always wonder how ya'll get that much bottom time off an AL80? I watch all of my DMs to see how often they exhale.... I think ya'll have gills or something.... What's the secret?

 

[chillyinCanada]

What kind of profile are you people diving to get 90 minute dives. I regularly outlast everyone on the boat except the dm but pretty sure have never had a 90minute dive. Of course, any time extended dive is somewhat discouraged most places when other divers are waiting on the boat AND there are SI issues and schedules to follow. Be that as it may, please sdvise as to your profiles. Thanks!!

 

[Mike]

90 minutes at 12 ft?

Depth certainly has to be a huge consideration. The typical long bottom time dive in Cozumel is Columbia shallows because its so -- shallow, and I guess paradise would be next. Other than that, I'm never going to see 90 minutes on an al80 in Cozumel, not with the typical deeper profiles you dive there and being a dude. In Bonaire it's not hard to do a 90 minute dive off an al 80 since it's a 3 level reef and it's pretty easy to plan your dive as 40 minutes against the current at 50-80 ft, 30 minutes back with the current at 50-30 ft, to around your entry area and then easily spend basically a 30 minute safety stop at the end of the dive on the shallow reef at 20-10 ft. But for me it's going to be profile driven and unless we are shallow I'm not going to even see much over 50 minutes on an 80 at best.

 

[Ron Lee]

I am tired of people being tired with the argument...or I am tired of being tired.

It really should not be arguable. 120 cu ft is roughly 50% more air than an AL80. Take a large number of people and in almost every case, each person will be able to make a longer dive at a constant depth or a longer dive with a more challenging air demand using a 120 cu ft versus a 80 cu ft tank.

Sure plenty of people can outlast me with their 80 cu ft tank versus my 120 cu ft tank. But they could outlast me longer if they had a 100 cu ft or 120 cu ft tank.

Real life reality check. Had the three divers on the bungled old Scuba Mau dive been using 120 cu ft tanks, maybe the one who died would still be alive and the dive master who was paralyzed might not be. This is unsupported opinion and using 120 cu ft tanks on air would not be enough for me to try what they did.

 

[DjDiverDan]

I love the HP Steel 120, and not just for the extra air (which I can definitely use!). Yes, I'm an experienced diver, with about 620 logged dives over the course of 24 years. But I'm also LARGE -- 6'1", about 275 lbs, and buoyant, and I'm only diving 2 or 3 weeks out of the year, so my breathing is not what it would be if I were constantly in the water. SAC is also a function of body mass - larger people need more O2 to keep everything working. All other things being equal, I am going to use at least twice the amount of air as a 120 lb female doing the exact same dive. So I can see why an AL 80 is plenty for Christi, but don't ask me to meet the same standard of air consumption. Also, with an AL 80, I need at least 23 lbs of lead to descend, 25 if I don't want to fight to stay down on a safety stop because my tank has gone positively buoyant at 700 psi. The HP Steel 120 cuts down my weight needs by a LOT, and doesn't go positive toward the end of a dive. Sure, I can see that the Steel tanks would be too heavy for someone who needs very little weight to descend with an AL 80, and why it would roll her with all of her weight in the tank. I still need enough extra weight, which I can put up front, so that is simply not a problem.

 

[Mossman]

I love the HP Steel 120, and not just for the extra air (which I can definitely use!). Yes, I'm an experienced diver, with about 620 logged dives over the course of 24 years. But I'm also LARGE -- 6'1", about 275 lbs, and buoyant, and I'm only diving 2 or 3 weeks out of the year, so my breathing is not what it would be if I were constantly in the water. SAC is also a function of body mass - larger people need more O2 to keep everything working. All other things being equal, I am going to use at least twice the amount of air as a 120 lb female doing the exact same dive. So I can see why an AL 80 is plenty for Christi, but don't ask me to meet the same standard of air consumption. Also, with an AL 80, I need at least 23 lbs of lead to descend, 25 if I don't want to fight to stay down on a safety stop because my tank has gone positively buoyant at 700 psi. The HP Steel 120 cuts down my weight needs by a LOT, and doesn't go positive toward the end of a dive. Sure, I can see that the Steel tanks would be too heavy for someone who needs very little weight to descend with an AL 80, and why it would roll her with all of her weight in the tank. I still need enough extra weight, which I can put up front, so that is simply not a problem.

I totally agree with you, probably the first time for me

I'm a bit lighter and have a handful more dives, but our lungs are probably similarly sized. I remember being on a group trip in Coz when a guy who came up to my waist lectured me on my heavier air consumption. I informed him that since I was about two of him, I should be using twice as much air!

 

[Mike]

Would you like more horse power or less horse power? I'll take more horse power.

Would you like a raise so you make more money or just wait till next year? I'll take the raise.

Hot girl or ugly girl?

Hamburger or double cheese burger?

Poor husband or rich husband?

One beer or two beers?

Regular size or super size?

Smaller tank or bigger tank?


I sense a pattern.

Scubaboard is a weird place, if a thread goes on long enough it turns back upon itself and eats itself, turns into a black hole where all logic and reason disappear, the sky is no longer blue, water is no longer wet, and small tanks are preferred to larger ones.

The only thing that really puzzles me is why only 3 dive operators have gone to larger tanks? Seems like a total no-brainer to me, when you look around and see one of the most successful operators offers large tanks why that wouldn't be on your radar? I'm goofy like that, I see success and I want to take the easy road and just copy it instead of fighting it or be mad at it.

 

[chillyinCanada]

:chuckle: a bold little bugger wasn't he?

 

[Christi]

What kind of profile are you people diving to get 90 minute dives. I regularly outlast everyone on the boat except the dm but pretty sure have never had a 90minute dive. Of course, any time extended dive is somewhat discouraged most places when other divers are waiting on the boat AND there are SI issues and schedules to follow. Be that as it may, please sdvise as to your profiles. Thanks!!

Will be glad to post some profiles. I'll pull the trip logs and post some tomorrow.

---------- Post added May 7th, 2014 at 10:59 PM ----------

Would you like more horse power or less horse power? I'll take more horse power.

Would you like a raise so you make more money or just wait till next year? I'll take the raise.

Hot girl or ugly girl?

Hamburger or double cheese burger?

Poor husband or rich husband?

One beer or two beers?

Regular size or super size?

Smaller tank or bigger tank?


I sense a pattern.

Scubaboard is a weird place, if a thread goes on long enough it turns back upon itself and eats itself, turns into a black hole where all logic and reason disappear, the sky is no longer blue, water is no longer wet, and small tanks are preferred to larger ones.

The only thing that really puzzles me is why only 3 dive operators have gone to larger tanks? Seems like a total no-brainer to me, when you look around and see one of the most successful operators offers large tanks why that wouldn't be on your radar? I'm goofy like that, I see success and I want to take the easy road and just copy it instead of fighting it or be mad at it.

who is mad? and not everyone wants or needs to be the biggest shop on the island