Using a HP 120 instead of a HP 80?

[SteveTW]

Hi to all! I'm very new to scuba and have most of the gear that I need but was wondering about tanks. I did all of my training and check-out dives with an 80cf tank and was thinking about buying my own 120cf tank. What are the pro's & con's on this?
Thanks,
Steve

 

[mark99]

In my opinion choice of tank depends a lot on your physical size. The HP 120 is a few inches taller than typical 80 or 100 tanks. If you are not tall you can have issues with the bottom of the tank hitting your backside or your head hitting the valve. It is also a bit heavier out of the water. That said, my daughter is 5'7" and has dived my backup 120 with no problems (although I wouldn't have recommended it for her as her "ideal" tank), and I am much taller and trim out perfectly in twin 120's.

Another positive on a larger HP tank is that if you get an underfill of the 120 say to 3000 psi then you still have over 100cf of gas.

 

[JBRES1]

Pro 120 cu ft of gas vs 77 cu ft.
Pro longer bottom time for the 120
Pro for 120, less weight on belt (aprox 5 to 10 #'s less lead required)
Con for the 120 is that some shops don't fill to the full 3400 to 3500 .
Con for the 120- its too big for some divers, and can roll you over on your back.
I love diving with a 120 because my buddy also dives a big tank and we get alot of bottom time.
Jim Breslin

 

[CAPT HOOK]

One big thing to consider is if you are diving from your own boat or a a charter; most charter limit your bottom time, do a big tank doesn't convert to longer dives.

 

[RJP]

most charter limit your bottom time, do a big tank doesn't convert to longer dives.

Most is a big word, and borders on an over generalization. Perhaps you meant "some" or even "a few"?

In fact, I've never, ever been on a charter that put a bottom time limit on divers. Certainly not a boat where people bring their own tanks.

 

[Randy43068]

I use a steel HP120 with my single wing because it allows me to trim out really well. I'm five foot nine and it's not too long of a bottle for me.

 

[spectrum]

What you will be doing for dives and your buddies is a big factor.

If you already see yourself doing a lot of boat trips to reasonably deep sites you may have good need for something bigger than an 80. On the other hand if you like shore diving you can have a lot of fun with an 80. In any event since you are a cold water diver going with steel, whatever the size or pressure is the way to go. My rant.

If you have average or better air consumption and your buddies dive 80 CF tanks there is little point in you lugging a bug cylinder around. You being a new diver probably don't have much of this in focus yet so it's a little like reading tea leaves.

There are some nice Low Pressure 77CF cylinders out now that are comparable in size and capacity to an aluminum 80 with much better buoyancy properties. You can get 2 of those for almost the same money as a single HP 120. Just a thought. Having your own gear, including cylinder(s) is a big key to diving frequently and progressing in the sport.

Pete

 

[Richesb]

Size of your tanks should be in relation to your physical size, where you plan to dive (cattle boat vs. private boat), depth you plan to dive.
Having a tank thant holds more gas than you have allowable bottom time is no advantage. This will cost you money filling partially full tanks.
As far as fill pressures. ANY HP tank regardless of size if not filled to 3400psi is not filled to capacity.

 

[scubabeachboy]

Steve:

I switched over to HP DIN valve tanks a few years back.
I have 2 HP 120's and 2 HP80's.
I definately like my HP tanks.
The 80 is real small for shallow/short dives, and the 120 is just right for a deeper dive.
I went on the HMS Yukon with a 120, and use most of the air in 1 tank.

The other nice thing about HP tanks is that they remain negatively boyant when empty.
This is good beacause you need less lead weights for the end of dive to control you assent.

About the only draw back I have seen is some boats cant fill em to max allowed pressure, and the 120 is a bit of a bear till you are in the water.

I used to go on a dive boat from Long Beach, the boat had seats at the hulls edge, we would suit up all gear, the dive master would check us over, pull down warm water hose to fill suit voids, then remove a guard rail and allow us to roll into water without having to stand. Very good setup.
The boat is "Sea Ray", I think.

Dump those aluminum 80's and go HP-DIN!

 

[ronbeau]

Hi to all! I'm very new to scuba and have most of the gear that I need but was wondering about tanks. I did all of my training and check-out dives with an 80cf tank and was thinking about buying my own 120cf tank. What are the pro's & con's on this?
Thanks,
Steve

You might want to also consider an HP 119 depending on your height. The Worthington HP 119 is the same length as an HP 100 (24 inches) but is 8.25 inches in diameter instead of 7.25 inches in diameter. It weight 9 pounds more than an HP 100 however (42 pounds versus 33 pounds).