Scuba Diving Equipment Guide

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Scuba Diving Articles - Learn To Scuba Dive
Monday, 03 November 2008 22:06

What's a "fully equipped" diver? There's no single answer to that question because equipment requirements vary with the dive environment and purpose. If you go ice diving, for example, you'll need a lot of thermal protection, whereas in the tropics you need comparatively less. Special activities call for special equipment; if you want to take pictures on the dive, you'll obviously need an underwater camera system.

Within these variables, however, regardless of the dive specifics there's a basic equipment set that you need as a recreational diver. The same is true if you get into technical diving. Let's look at each of the components in these basic equipment sets.


Mask, Snorkel and Fins

Sometimes called your "basic" gear, these three cover the minimum "adaptations" you need as a diver: seeing, breathing and swimming with your legs instead of your arms. When you put on scuba gear, you still need the mask so you can see and the fins for swimming. You still use the snorkel to save air at the surface, or in case you have to make a long swim (planned or unplanned) with an empty cylinder, especially if there's a current or chop. Except in a few instances, the snorkel is considered required recreational scuba equipment even though you can breathe from your scuba system.

In technical diving, you usually omit the snorkel because it causes more problems than it solves. However, tech divers do equip with snorkels in some circumstances, such as if they may end up a long way from a boat and have to wait for it to pick them up.


Exposure Protection

You'll want an exposure suit of some kind on all dives to protect you from heat loss and from abrasion. As covered in Chapter Four, water conducts heat from your body about 20times faster than air at the same temperature. Because of this, you can become dangerously chilled in water temperatures that would be comfortable in air. In very warm water you may not need thermal protection, but you still benefit by wearing something to protect you from incidental scrapes and stings.

Exposure suits include lightweight body suits (a.k.a. skin suits), wet suits and dry suits. You use body suits in warm water primarily for abrasion protection. Wet suits provide more insulation, making them suited to longer dives in warm water as well as cooler water diving. Dry suits provide the most insulation, enabling you to dive in cold waters, including at the Arctic or Antarctic. Besides suits, you'll usually wear some form of hand and foot protection, and in cooler water, a hood. Because tech dives can be two or three times longer than recreational dives, tech divers generally wear more insulation (almost never body suits) compared to recreational divers for the same temperature water.


Weight Systems

Exposure suits are buoyant, and you may be, too, depending upon your physical characteristics. When diving, you use a weight system to just offset any buoyancy, thereby letting you swim gently downward. You don't wear so much weight that you sink rapidly. Weight systems may be a belt, a harness or integrated into your BCD. In recreational diving, a weight system must have a quick release by which you can jettison your weight with one hand - just in case you end up in a situation in which you want to be sure you stay at the surface. You may need a weight system in tech diving, but frequently you do not. Tech gear may be so extensive and heavy that there's no need for any weight system at all, even with a very buoyant exposure suit. If you need weight on a technical decompression dive, the dangers caused by losing it may be higher than any difficulty jettisoning them. For this reason, tech divers commonly have a weight system that requires operating more than one release to get rid of the weight.


Scuba System

The standard recreational scuba system consists of three integrated components a high pressure compressed gas cylinder, a regulator and a Buoyancy Control Device (BCD). Each of these has subcomponents.


High Pressure Compressed Gas Cylinder

This is a steel or aluminium cylinder than holds air (or enriched air) typically at a full pressure that ranges from 150 bar/2250 psi to 200 bar/3000 psi. You typically wear a single cylinder in recreational diving. Tech divers typically wear double, high capacity cylinders joined by a special valve (manifold).



Your regulator delivers air from your cylinder on demand when you inhale. It does this by reducing the compressed air pressure to the match the surrounding water pressure in two steps or stages. Your regulator also has an alternate air source for sharing with a buddy in an emergency and an SPG (submersible pressure gauge) so you know how much air you have at all times. A third hose, call the LPI (low pressure inhalator) supplies air to your BCD.


BCD (Buoyancy Control Device)

Your BCD is an inflatable jacket that you wear. It holds your scuba system together and allows you to control your buoyancy by adding or releasing air. By inflating or deflating the BCD, you can float easily at the surface or swim effortlessly over the bottom. Your BCD may also include your weight system. Tech divers use a similar scuba system, but with some important differences. The tech diver has two completely independent regulators and uses a wing-type BCD with a separate harness. The wing-type BCD sandwiches between the cylinders and the harness; tech BCDs may have two independent bladders and inflation/deflation systems.



Besides needing to know how much air you have, you also need to know how long you've been underwater and your depth to avoid decompression sickness. At the minimum, you'll need an underwater timer or watch and a depth gauge, though it is more common to use a dive computer. Dive computers help you avoid decompression sickness by applying time and depth information to a decompression model. In addition, you use an underwater compass to assist finding your way.

In tech diving you need the same instruments, but you always have two timing devices and two depth gauges - typically dive computers. In recreational diving you may opt to mount your instruments into a console, but in tech diving you wear instruments on your wrist.


Knife / Cutting Tool

Although it isn't common to get entangled, it does happen, so having a cutting tool of some kind is standard equipment (except where prohibited by law). The typical choice is a dive knife, though you may prefer special shears and other cutting devices. In tech diving you go one step further, always having two cutting tools, one of which you can reach with either hand.


Signaling Devices

In many situations, you can be hard to see if you surface a long way from the boat due to currents or a dive plan error. Audible and visual signaling devices attract the attention of boat crew or other divers for pickup or emergency assistance.

Dive Tables / Planners

As a recreational diver, you always stay within depth and time constraints that allow you to swim directly to the surface at any time should the need arise. Although you use a dive computer to help you stay within these limits, you use dive tables to plan your dive and as a backup in case your computer malfunctions. The Recreational Dive Planner (RDP) is by far the most popular table for this, though you can choose from others, such as the US Navy tables (which you can find laid out in different ways for convenient use). You use underwater slates to carry dive plan information, as well as to communicate. Tech divers make dives with required decompression stops at specific depths and times. You would use somewhat more sophisticated dive computers to determine these depths when tech diving, but you still need dive tables for planning the dive and to consult in case of a computer problem. Rather than use pre-printed tables like the RDP, in tech diving you create custom dive tables for a specific dive using desktop decompression software.


Dive Log Book

Your certification cards establish your training qualifications, but it's your log book that tells what you've done with those qualifications. By keeping a log book, you create a tangible record of your dive experience, which some resorts and live-aboards will want to see. As you move up through the diver training ranks, you'll need your log book to establish that you meet experience minimums required by many courses. The typical log book is on paper, though you can get computer programs that log your dive. If you prefer to log your dives in a computer, you'll carry printouts that summarize your experience.





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