Should I stick with Steel 120 Tank??

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If you're diving cold water, you'll either have the weight on your back as in the tank or the weight on your hips with a weight belt - If it's a HP120, keep and use it.

It takes x number of pounds to get you down, I'd rather it be in the tank.
 
If you keep the 120, may as well go out now and buy a matching second tank. You usually do two dives and using a non-matching tank will mean reconfiguring your weights on the second dive.
 
I was told they were 80's..so I would think so. They were they same size as my dive partners and hers was an aluminum 80. I was pondering the 100.
Same size as the AL80 is an HP100, which would make more sense with the 500# difference than an 80.
 
Hey all,

I am a new diver. Did my OW dives 1 and 2 yesterday for my Padi cert and have 3 and 4 next weekend. I have a steel 120 tank that I got off a buddy that no longer dives. This past weekend I was diving with a steel 80.Dives went great (man what an awesome experience!!!). However, walking back to the parking lot I was freaking exhausted lol. Especially after dive number 2. Looooong walk up the beach. The 120 I have weighs a freaking ton, and gets me about an extra 500lbs of air vs the 80 I was using. So my question is, should I sell the 120 and get something a little smaller? Most of my diving will probably be from shore and in cold water. (I'm in New England) so full suit, hood and gloves. I'm trying to figure out what the advantage of having such a big tank is. I'm a big guy...6'0 275. Any input is welcome.

Thanks!!!

V...

Read through all the posts...no mention of how much ballast your lugging...

As you progress you'll be able to lose a good portion of your ballast through trim and neutral buoyancy improvements...

Further...drop your ballast at the beach and go back for it...as opposed to lugging it to the car with your kit...

You may also want to consider a hand cart...preferably with pneumatic tires...save your back and your knees...Home Depot...$60...as photo attached...plus a few bungees/ratcheting tie-down straps...

I also made a small wooden table...large enough top for an assembled kit...high enough to get kit on in standing position for shore diving...

At your size I wouldn't be swapping out 120's for 80's...or even 100's...there's lots of ways to lighten the load getting to and from the car...without sacrificing gas volume...which you will be glad you have once you've advanced...

Best...

Warren...

hand cart.jpg
 
The 120 I have weighs a freaking ton, and gets me about an extra 500lbs of air vs the 80 I was using.

Just to be clear the steel 120 is giving you 40 cubic feet more of gas over the aluminum 80. Yes, the 120 when full will have 3500 psi compared to 3000 psi for the 80 but you’re getting 50% more gas. 120 cu ft vs 80 cu ft.
 
They may have said you were on an 80 based on size. Not knowing that is was steel and had a higher fill pressure. Quick glance they are the same physical size and the aluminum version is so much more common.

I would keep it, providing it is a high pressure 120. A low pressure 120, sell it to a Florida caver who will do cave fills with it.

I prefer steel 100s over AL80s personally. Shifts a few pounds of weight off the belt to my back. Overall package weighs the same, better balanced in the water, and more air.
 
Hi @Viper12161

You should dive the size cylinder you need to be able to successfully execute the dives you are planning. This will depend on your gas consumption rate (RMV), the depth, the NDL time at that depth, and the reserve pressure you would like to end with. As a new diver, your gas consumption will probably be on the higher side Average Gas Consumption. It should improve as your buoyancy, trim, and propulsion improve, along with greater experience diving.

As an example, say you do a dive to 60 feet on air and that your RMV is 0.8 cf/min. The NDL for this dive is dependent on the computer or table you use but will be in the neighborhood of 45-55 min. Say you want to surface with 500 psi, though this might not always be the case.

The gas you would need for a variety of bottom times is shown here (the gas use also includes the ascent and safety stop):
25 minutes 59 cf
30 minutes 70 cf
35 minutes 81 cf
40 minutes 93 cf
45 minutes 104 cf
50 minutes 115 cf
55 minutes 127 cf
So, assuming a complete fill of 3000 psi for an AL80 (actually 77.4 cf), and 3442 psi for a HP steel tank, you could do a 25 min dive on an AL80, almost a 30 min dive on a HP80, a 35 min dive on a HP100, and almost a 45 min dive on a HP100. It would seem that your dive time would generally be limited by your gas, you might approach your NDL with a HP120, depending on your computer/table.

Of course, to make these calculations, you need to have an idea regarding your RMV, I would imagine you do not have that yet, but should consider collecting this kind of information to help you with your gas planning.

On the bottom of this page you can see a summary of some cylinder characteristics High Pressure Steel Cylinders - Hot Dip Galvanized | Dive Gear Express® The lightest full tank is the steel 80. An AL80 is about 3 lbs heavier, a steel 100 about 7 lb heavier, and a steel 120 about 14 lb heavier. A steel tank will allow you to take some weight off your belt or out of your pockets, somewhere around 3-5 lbs.

Best of luck and good diving,

Craig
 
I dive two LP 120s in a sidemount configuration. I went and redesigned a cart to work better for my kind of diving.

full?d=1393623361.jpg



Right after I finished adding the big wheels and tank control rings.

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All loaded up!
Two tanks, a deco bottle, helmet and my fins and mask are wedged in cracks on the back of the cart.
 
Correct me if Im wrong, but as you say you're in cold water w/ a full suit & hood -- Don't you still need to add weight on top of the tank? As other pointed out.

I don't know that a smaller tank will make much of a difference. It may move some of the weight off of your back and onto your hips. Then again, that may mess with your trim and you may need to keep the weight on your back after all.

Unfortunately, hiking around with a scuba kit is exhausting. I feel your pain. Just part of the package of local shore diving. Edit - although the handtruck suggested above would help.

I am of the opinion that there nothing wrong with having too much air. I'd stick with the 120. I was looking around for tanks for my cold water local diving, and my preference was steel 120 or 100. At least around here, 120s were rare and expensive, so IMO your friend bequeathed you a valuable resource.
 
https://www.shearwater.com/products/swift/

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