Scuba Tank Comparison Chart???

[spectrum]

I don't know why but I have been partial to this reference chart.
http://www.huronscuba.com/equipment/scubaCylinderSpecification.html

Color, especially yellow can be invaluable in poor visibility. Unfortuantely there is no such thing as a well worn good looking yellow tank. Settle for colorful fins and so forth.

A High Pressure steel cylinder will have the best weight to capacity ratio. The 80 CF 3442 cylinders from Worthington or a PST is available are beautiful things. If you are a bigger user then the 100CF sister would suit you well.

Can you have too much air? There comes about where you are just lugging mass and burning air to carry air. Trying to match your capacity with your GF makes sense. It also depends on you and your dives. I can go out for a 70 mnute shore dive with an E7-80 and come back with about 800/ 1000 PSI. By then I have had a good time and someone is cold, tired or running low on air so for such a dive why carry more? The right cylinder for the dive.

Brand? Worthington and PST (if they return or you find used/stock) are the players. Faber is in there too but they paint their cylinders and they are heavy. The extra weight will come off of your belt but they will be heavier to handle and may make you or your GF top heavy. Worthington and PST cylinders are hot dipped galvanized and very durable.

Home painting of cyliders is futile and invites other problems.

I'm not aware of any stainless coating inside or out.

Steel \ ALuminum? Find some old threads and get a bag of popcorn. My money is on HP steel. Also see my rant: Worthington and PST

Length will not hurt you for drag. For the sake of trim many taller divers prefer a longer tank to distribute the mass better. Common cylinders range fro 6.9 to 8 inches in diameter. It's not a huge change in diameter but it is a considerably bigger hole to punch in the water. With the diameter will come more cylinder mass to swim around. Any diver can be configured to be neutral with any cylinder. The bouyancy will change during the dive as you breathe the air. Air weighs about .08 pounds per CF. Breathe 70 cubic feet and you will be 5.6 pounds more buoyant. This is why you configure your weight to be neutral at the end of the dive. Otherwise you will ascend uncontrollably.

Pete

 

[jpcpat]

What is the definition of "real weight" in the Scubadiving chart? Thanks!

"Real Weight" is usually tank weight + Bouyancy empty; in other words, the total weight you carry, including the lead to sink the tank. Steel tanks are often a bit heavier, but less bouyant, so their "real weight" is often less

 

[SuSexFulDiver]

LOUMA

Both me and my girlfriend just got certified this past sunday, we started class together.

I know I need to get more dives in before buying equipment, but while out on the boat on our way to the island some guys were talking about different tanks and the cubic capacity and such, and I was lost on what they were talking about. That is the main reason why I want to learn more on tanks. I also see nothing wrong with having a tank a bit larger than my girlfriend.

I have much larger lungs than she do. The dive doctor I saw before my cert class started gave me this thing called a "Asmaplan+ Peak Flow Meter by Vitalograph"

Basically its for me to blow into before each dive or other outdoor activities to determine if my very rare ashma or allergies are affecting my lung capacity. The device measure how much air volume my lungs are holding. Well when I blow into it, I can blow 700 L/Min the max on it is 800 L/Min. Well when my girlfriend blow into it, she can only get the meter up to 450 L/Min. So its obvious my lung capacity is much larger than hers.

I know I need to work on my breathing underwater without a doubt, but I also know that I will always use more air than she do.

I want to learn as much as possible about all Dive equipment.

 

[SuSexFulDiver]

Spectrum

Thanks for all the great information, you pointed out a few things that I did not think about.

 

[CompuDude]

My favorite tank, hands down, is the HP100.

Readily available. Weight comes off your belt. You're already used to Al80's which 99% of people learn to dive on. HP100s weigh the same on land, but they're heavier in the water so that weight comes off. They're also a few inches shorter and I find them easier to lug around than Aluminum 80s.

And best, is that no matter what the compressor is capable of, you're going to have more gas inside an HP 100 than an Al.80 at the same pressure. And if you can get a good fill to make it full, you have over 20% more gas than an Al.80 holds (77.5 vs. 100cf).

If the weight is too much, than the cheap Al.80s were too much for you to handle, too. If you can handle the Al.80s, you can handle the HP100, so why not go bigger? Better to surface with extra gas than not have enough! But if it IS too big, you can go for the HP80, which is a sweet compact package for the smaller diver.