A steel scuba tank weighs between 28 and 30 pounds, while an aluminum tank weighs between 31 and 35 pounds. A scuba tank’s weight depends on its material, manufacturer, and whether it is full or empty.
In this article, we explain the nuances of tank weight and how they factor in next to the weight of other scuba diving gear.
Does a Scuba Tank Weigh More Full?
Scuba tanks weigh marginally more when full.
Assuming you’re using air in your tank, it weighs about 0.073 lbs (0.033 kg) per cubic foot. An average tank holds 80 cubic feet of air, so a full tank adds on about 5.9 pounds to its dry weight.
Do Empty Scuba Tanks Float?
You need to look at a tank’s natural buoyancy to determine whether it will float when empty.
Aluminum tanks have a natural positive buoyancy, and they are likely to float when empty. While these tanks are negatively buoyant when full, this becomes more and more positive the more air you use.
Steel scuba tanks have natural negative buoyancy when empty in most cases. Certain manufacturers may have steel scuba tanks that end up neutral or even positive, so you should check this information before assuming.
Why Do Scuba Tanks Weigh so Much?
Scuba tanks are made of heavy metal, which naturally weighs more than other objects of similar size. Steel weighs about 0.283 pounds (0.13 kg) per cubic inch, and aluminum averages 0.098 pounds (0.044 kg) per cubic inch.
Another detail that factors into scuba tank weight is its construction. You may see a hollow canister to hold air, but scuba tanks require many layers of steel or aluminum to create walls that can safely withstand the pressure of air in the tank.
Steel, which weighs more, is much stronger than aluminum, so it takes less steel to safely hold the air you need to breathe. While aluminum weighs less than steel per unit, you need thicker walls in your scuba tank to provide durability and keep your tank intact during your dive.
How Much Does Scuba Gear Weigh?
A full set of scuba gear weighs about 40 to 50 pounds (~18.14 to 22.68 kg) on average, but a wider range encompasses 10 pounds to 80 pounds (4.54 to.36.29 kg).
While the scuba tank makes up the majority of this weight, the rest is spread out amongst:
- Your diving suit
- Your valves and regulators
- A buoyancy control device
- Dive weights
There are other small items that add up when carrying them together with the rest of your gear.
Diving Suits
Diving suits come in a variety of styles, usually:
- Dive skins
- Wet suits
- Dry suits
Dive skins barely add any weight or buoyancy, and you can expect as little as 1 or 2 pounds (0.45 to 0.9 kg).
The thicker a diving suit gets, the more it weighs. Thickness often ranges from .5mm to 8mm, and weight can get up to 7 pounds (3.18 kg).
Valves and Regulators
Your valves and regulator, which are necessary to control the compressed air flow from your dive cylinder, usually add a pound or 2. This weight is usually unnoticeable, but keep in mind that weight fluctuates with these items.
Buoyancy Control Device (BCD)
A dry buoyancy control device weighs anywhere from 2 to 5 pounds (.9 to 2.27 kg).
These devices have a number of integrated features that determine weights. These include:
- Metal backplates
- Inflatable sections
- Different attachment options
- The inflator/deflator device
- Pockets for dive weights
The weight also varies depending on the design of your BCD.
Dive Belt and Weights
Each weight can add anywhere from 1 to 4 pounds (.45 to 1.81 kg), but most dive belts add little to your overall weight.
Advanced breathing techniques may limit the additional weight you need to tack on, but a general rule asks for 10 percent of your body weight.
Other Gear
Expect some extra pounds for slighter gear such as:
- Your snorkel and mask
- Dive gloves
- Diving boots and/or fins
- Depth gauges
- Dive computers
While none of these weigh anywhere near what a scuba tank does, all the little parts add up.
Steel vs. Aluminum Scuba Tanks
Steel tanks start off negatively buoyant and stay that way for the remainder of your dive. They may become neutrally buoyant, but not by much as they’re emptied. Steel tanks will not float like aluminum tanks do when emptied, but this is not guaranteed.
Your aluminum tanks are negatively buoyant when full, but they become positively buoyant as they empty. Most, if not all, aluminum tanks will float to the surface when completely empty.
Aluminum is softer than steel, so it is more likely to dent, crack, and scratch. However, aluminum is cheaper and easier to maintain.
Most recreational divers opt for aluminum, but deep divers or professional divers tend towards steel tanks.
References
https://www.wetsuitwearhouse.com/blog/how-heavy-is-a-scuba-tank-gear/
https://www.theworldmaterial.com/weight-density-of-aluminum/
https://www.scuba.com/blog/scuba-guides/choosing-steel-aluminum-tanks/