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DaveMann
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Your Opinion: Al 63 vs Steel 72

Wed Aug 24, 2016 1:20 pm

I will have an opportunity tomorrow, 8/25/16 to buy a couple of tanks. I have not laid eyes on them yet so I'm not sure of manufacturer, but a pair of aluminum 63s or steel 72s will probably be coming to live at my house.

My considerations are buoyancy characteristics, height (or length) of tank, ease of use as doubles (tank bands manifolds etc), vintage cool factor, etc.

Is there anything I haven't considered? Which way would you go, and why?


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Bryan
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Re: Your Opinion: Al 63 vs Steel 72

Wed Aug 24, 2016 5:05 pm

My two cents...avoid any aluminum cylinder made before 1990 like the plague. It is worth neither the hassle nor the risk period. Next, unless you KNOW bands and manifolds are available for any two cylinders you are planning on using as doubles don't plan on it happening.
Steel 72's with 3/4" valves should be no problem (1/2" is a different story) BUT that depends on the dive shop you going to using a hydrotesting facility that knows what they are doing. The dive shop will then need to VIP and sticker the cylinder if you plan on getting air at a dive shop. So if you are uncertain about any of the above it can all be a crap shoot. Making doubles out of steel 72's should not be a problem finding a manifold for ....Bands can be a challenge but Allan can always make a harness if you can find bands.
Trying to be cool aside.....Ask yourself if you really want to haul around a pair of double 72's on a 30' dive in the keys when most guides limit you to 60 minutes? Double 72's are HEAVY especially climbing back on a moving boat up a flimsy ladder.....Perhaps you have your own agenda, dive boat, other locations lined out.....
Many of the folks on the forum are extremely skilled and resourceful when it comes to putting together various sets of double and triple cylinders. Unless it's a specific vintage event my triples stay home and I'll dive whatever the boat already has on it or the operator is providing.
Doing it right should include some common sense, not just blindly following specs and instructions. .Gary D, AWAP on SB

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DaveMann
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Re: Your Opinion: Al 63 vs Steel 72

Wed Aug 24, 2016 7:17 pm

Good points all. Fortunately both the 63s and 72s have been hydro'd and VIP'd within the last month or so. So I have a bit of time before I need to worry about that again. Also, the 63s are not the hot pink DACORs I mentioned in a previous post, these are only about 5 years old.

I wouldn't have thought bands and manifolds would be such a problem. I will investigate further.

Pairing up either of these tanks may sound like a heavy chore, but I'm used to it. My current rig is a pair of al 80s. No manifold, but two regs, two SPG, two safe seconds on an Ocean Quest BCD with a (big chunk of extruded aluminum) twin tank adapter instead of bands.


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simonbeans
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Re: Your Opinion: Al 63 vs Steel 72

Wed Aug 24, 2016 7:29 pm

The two tanks are different diameter. Thus you could run into band/manifold issues. As for valves, many are around for the 71.2s as well as new, vintage style bands. Not sure about the 63s.
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Nemrod
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Re: Your Opinion: Al 63 vs Steel 72

Wed Aug 24, 2016 8:06 pm

Catalina and Luxfer 63s are slightly different in buoyancy characteristics. I have two Catalinas. I use them for shore diving mostly and have used them on my kayaks as well. They dive great, balance well and have very neutral characteristics. The few cf disadvantage against steel 72s (at 2250) is of no concern to me.

Kind of like the argument that any gun is better than no gun in a deadly encounter with bad things, any tank is better than an empty one that shops refuse to fill. Of course, once you find a shop that will accept the 72, well, yeah, they are great.

Another argument in favor of the 63 is their 7.25 inch diameter is the same as the almost universal aluminum 80.

I have a fleet of nice 72s, am partial to them, but the truth is that traveling with them, especially in Florida is a PITA. It is what it is, I tire of arguing with bone heads, makes the day go better all around.

The 63s fit in my kayaks better than 72s and I have the Roll Control brackets on my Whaler set at 7.25 inches so my poor 72s all sit huddled together in the secret underground Nemrod Lair all lonesome and out of hydro. :(

One thing, aluminum tanks are cheap. I see no point in purchasing used aluminum tanks more than a few years old unless they are really cheap.

I said I had two 63s, last year I left one on the beach or I would have three. I bought it while in Florida and when I did my last shore dive simply left it at the Datura portal for some lucky diver.

Nem

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DaveMann
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Re: Your Opinion: Al 63 vs Steel 72

Wed Aug 24, 2016 8:54 pm

Well there's something I wasn't aware of - Florida has boneheads in it! :wink:

I'm guessing you have a hard time with the charter boats using 72s, and with your LDS in getting them filled. I can see why the floor in the secret underground Nemrod Lair might be settling a bit in that corner.

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Re: Your Opinion: Al 63 vs Steel 72

Wed Aug 24, 2016 9:13 pm

I picked up 2 luxfer 63s the other day and they are just a shade shorter than my hp100s. I got rid of all my 72s because I didnt like the length when wearing them low on the back.

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Re: Your Opinion: Al 63 vs Steel 72

Wed Aug 24, 2016 11:08 pm

DaveMann wrote:Well there's something I wasn't aware of - Florida has boneheads in it! :wink:

I'm guessing you have a hard time with the charter boats using 72s, and with your LDS in getting them filled. I can see why the floor in the secret underground Nemrod Lair might be settling a bit in that corner.
I would not have a problem locally getting them filled, they have given up on me here and do as I ask. It is Florida, from one end to the other that I have a problem with. No, charters could care less what tanks I have, it is simply and only getting them filled in Florida. There are shops that will fill them but then I go back the next year and they will not but the shop that would not the year before now will. It is just more trouble than it is worth when a 63 can do anything a 72 can do without the hassle.

One little tip, do not have vintage decals on your steel 72s, that sets off red alarms in the White House apparently. OLD! Anything old is no good. You guys know that, do not you? :mrgreen:

Nem

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Re: Your Opinion: Al 63 vs Steel 72

Thu Sep 29, 2016 10:14 am

- Excellent and helpful discussion. My buddy Rich wants to make a set of doubles and has been considering the medium pressure Faber M71 tanks. They're stamped 3000 psi but are 71 cf only when filled 10% over to 3300 psi. Length 20.5 inches. He's got one but is having a tough time finding another that isn't something like $400 for one tank.
- I told him about Joe Diver selling brand new Twin 63s for only $125 ea. without valves. Your argument about (brand new alum tanks being so reasonably priced, why bother with others)... Makes a lot of sense. 63s make a lot of sense vs. 50s, I think.
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rhwestfall
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Re: Your Opinion: Al 63 vs Steel 72

Thu Sep 29, 2016 1:01 pm

AL63's on a solid bar "military manifold"
2e5s5lx.jpg
lots of air, little hassles....
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Ron
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Re: Your Opinion: Al 63 vs Steel 72

Thu Sep 29, 2016 4:07 pm

So this is just me, but I don't double any small tanks. for 120 cubic feet, you could just buy one steel 120. It's easier to VIP, you don't have to worry about the 3 piece doubles manifold leaking (if you use a 3 piece), etc. Double 72s are awesome. They are 144 cubic feet, and if you jam them a little bit, then they are double 160s. 120 cubic feet of gas just isn't enough gas for me to warrant making doubles which makes inspecting my own tanks a pain in the ass, carrying doubles, etc. Keep in mind that double 63s weigh 64 pounds without bands or a manifold, and a single 120 weighs only 39 lbs. My double 100s weigh about 75 pounds on land.

If you want doubles just to have them, then by all means do not let me discourage you. For vintage tanks, I only use double 72s. They are cheap, their buoyancy characteristics are good, and they can be overfilled a tiny bit if you like. Aluminum tanks tend to have bad buoyancy characteristics. As an example, both Luxfer and Catalina 63s are +2 lbs when they are empty. Assuming you have heavy bands, and a heavy manifold, then they will be neutral when empty which isn't super useful for ocean diving. Double 72s are still negative when empty with decent bands and a decent manifold on them, which for Puget Sound is super useful. Again, depending on where you live maybe having neutral tanks when they are empty would be a boon.

I am like Bryan on this matter. As a general rule, I avoid aluminum tanks. I also avoid doubles unless the dive warrants the gas. I don't use little doubles, because unless they provide an isolation manifold for redundancy they are only more failure points, and doubles generally are a pain in the ass. I say this as a dude who owns 3 sets of doubles. I know we are kind of past the OP's point at this point, but we do tend to have some good tank discussions on here and this certainly seems like one :)

YMMV.

Oh yeah, bonus nachos for the HP 120. You can cascade a HP120 @3500 PSI to top off your LP steel 72s. Roger Van Frankoooo showed me that one :)
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Bryan
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Re: Your Opinion: Al 63 vs Steel 72

Thu Sep 29, 2016 5:43 pm

Someone on here has triple 72s.. quite a piece of work.

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Re: Your Opinion: Al 63 vs Steel 72

Thu Sep 29, 2016 8:10 pm

+1 on the twin steel 72s. They are my favorite as well.

IMO triple 72s are too heavy. Most people will turtle (tanks down belly up) if you wear them. Just saying' but I've seen it happen.
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Re: Your Opinion: Al 63 vs Steel 72

Thu Sep 29, 2016 8:56 pm

slonda828 wrote:Re: 2xAL63 - "[neutral] -which isn't super useful for ocean diving"
Which make them fine for warm summer diving in fresh water.... not all of us are ocean divers.

regarding single 120's, even at 6'-7", I find them way too tall for use on a DH....

YMMV
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Re: Your Opinion: Al 63 vs Steel 72

Thu Sep 29, 2016 10:12 pm

USdiver wrote:+1 on the twin steel 72s. They are my favorite as well.

IMO triple 72s are too heavy. Most people will turtle (tanks down belly up) if you wear them. Just saying' but I've seen it happen.

For sure George. Even double 100s or double 120s will do this to me if I am not careful. It's a lot of ballast in one spot. It's funny, double 72s really are like the ideal tanks unless you need more gas. I often wonder about the engineering that went into the selection of that as a tank size back in the day.
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