Doubles vs. Single Tanks

Alternately referred to as diving cylinders or diving tanks (dependent largely upon whether the local region uses British English or Americanized English), tanks for diving can be organized according to a wide range of attributes, some of which are essential to understand, others of which are aesthetic or are matters of personal tastes. Regardless of your diving tank choices, if you're diving in the Bahamas, you're likely to want to pick a tank that makes you feel comfortable and enhances the overall aquatic experience.

The Pro-Double Side of Diving

For recreational diving, the choice between a single, large tank or two smaller ones is largely a decision of purely personal preference. While double tanks frequently increase drag, they also can allow you to maintain stability and overall balance more easily. They also can allow for increased capacity, making them preferable for divers interested in achieving longer dives.

Dual tanks don't need to be identical to each other in terms of overall size, structure or internal capacity. A 'pony bottle' is a smaller tank meant to be used after the air in a primary tank have been exhausted, and may double as either an emergency backup or a non-emergency extension of the primary. Bailout bottles strictly are 'worst case scenario' air supply tanks, to be used only in emergency situations. There is some overlap between these two types; a pony bottle may be a bailout bottle, although a bailout bottle is not (or, at least, should not be used as) a non-emergency pony bottle.

Most tanks used for diving in the Bahamas or similar tourist locales will use open-circuit structures that can be divided according to the amount of air pressure regulators. Cylinder systems with a separate, backup tank and twin tank systems both will include two independent regulators. Additional regulators beyond the first usually only are needed for diving in colder climates or emergency situations, and can add to the expense of purchase, maintenance, refilling and rental.

The Pro-Single Side of Diving

For short dives and casual diving experiences, many divers prefer the relative simplicity of single tanks, which easily have the capacity for recreational diving while minimizing mobility complications, equipment and expenses. Normal recreational diving is unlikely to place the diver in a situation where a backup or secondary air supply is required, in any case.

In warmer climates, single cylinder systems usually will use only a single regular.

The Other Options in Your Diving Tanks

Diving tanks can be categorized according to their internal gas capacity, with eleven liters (or 'Aluminum 80') being a standard for recreational diving facilities. Normally, a casual diver only will utilize 'back gas' style tanks, or tanks intended to be worn on the back and used as a primary breathing supply. By contrast, the less popular sling and side cylinders (often preferred in an Aluminum 40 size) are clipped to the side of the body or to a body harness.

The type of regulator connection also has some association with the local geography. A-clamps are favored around the world, but Europe and the United States are known for using specialized 232 bar DIN and 300 bar DIN connections. Fortunately, in the case of an incompatibility, adapters can be used to bridge this gap in design.