04. EQUIPMENT

Equipment plays a primary role in controlling buoyancy. In fact, everything worn during a dive and the way it is used has an effect on the diver’s buoyancy, and ultimately the ability to establish neutral buoyancy.

Understanding how to optimize and streamline equipment plays a key role in buoyancy control during all parts of the dive.

WEIGHTING SYSTEMS

In scuba diving’s infancy, weight systems were comprised of homemade leather belts and lead weights that were often struck in a diver’s basement.

Today, there are many more commercial options available to suit a variety of diving styles and preferences. Divers have the option to use solid lead weight on a traditional nylon belt, or bags of lead placed in a weight integrated BCD, among many others.

Regardless of what type of which weight system is used, they all share the same purposes: to offset the positive buoyancy created by the scuba equipment and exposure protection and to position it in an effort to balance the weights evenly.

Common weight systems in use today, including weight belts and integrated weight systems, are designed to distribute weight equally over the diver’s hips and in some configurations allow weight to be integrated into the back of the BCD, near the cylinder.

Most weight systems include a method to quickly release the weight when needed.

Weight belts typically have a quick release buckle that commonly open from left to right and include weight stops to prevent the weight from shifting positions during the dive and throwing off the diver’s center of gravity.

WET SUIT

Diving activities became much more popular with the advent of cellular neoprene. Because of its thermal properties and ability to protect  divers from the elements, neoprene suits are by far the most popular protection of choice for those participating in water sports.

Neoprene suits come in varying thicknesses and configurations; two-piece, one-piece, and semi-dry, for the different water conditions found in tropical, temperate, and colder waters. The thickness of a wet suit typically contributes to the amount of additional buoyant force it adds to the diver.

When fit properly, wet suits are designed to allow a thin layer of water to remain between the suit and the diver’s skin. The diver’s body warms the thin layer of water, which then acts as an insulator. For this reason, wet suits should fit snugly, but not be excessively tight. Most importantly, they should not overly restrict movement, or impede the diver’s ability to breathe.

A wet suit’s buoyancy characteristics will change as soon as it is exposed to water. Generally, thicker suits are affected more than their thinner counterparts. Additionally, wet suits that have been dry for several days or more will change their buoyancy characteristics during a dive slower than a suit that is already wet. A diver who gauges their weight needs before the wet suit has become wet will find that they are slightly overweight once the wet suit has become completely saturated.

As the diver descends, the wet suit will be affected by increasing hydrostatic pressure, which compresses the suit and reduces its positive buoyancy characteristics. It therefore becomes necessary for the diver to adjust the amount of gas in their BCD in order to compensate.

Consideration must also be given when a new wet suit is used for the first time. New wet suits have yet to be exposed to hydrostatic pressure and their cellular walls have not been compressed. For this reason, divers may need more weight than normal to offset the additional positive buoyancy. Less weight will be required as the wet suit’s cellular walls, and elasticity break down over time.

A wet suit’s properties will change over time, as will a diver’s own physiology; therefore, divers should test their buoyancy and weighting at the start of each diving season.

DRY SUIT

True to its name, a dry suit is designed to keep the diver dry for the duration of its service when used properly. There are many types of dry suits available, made from a wide variety of materials, each with its own features, benefits, and buoyancy characteristics.

Over time, dry suits have become more accessible and economical to the general diving public. They keep the diver dry and warm, and can be used in both colder and warmer waters, which eliminates the need for a wet suit. This is why SNSI not only recommends their use, but offers an option to learn how to properly use a dry suit during the SNSI Open Water Diver program.

Buoyancy control techniques, when using a dry suit, are much different than when using a wet suit. As such, specialized instruction in their use and hands on experience in a controlled environment is highly recommended.

Divers who have not yet learned the proper techniques of using a dry suit may contact an SNSI Instructor to enroll in the SNSI Dry Suit Specialty, which offers a more detailed and specific advanced use of a Dry Suit.

BCD BUOYANCY CONTROL DEVICE

In the early days of diving, SCUBA was sometimes referred to as “the device” or “twin cylinders” because of the two cylinders often used. The cylinders were joined at the base with a double cylinder boot, and at the top by dual-cylinder manifold. The manifold had a lever connected to a small rod that protruded near the bottom of the cylinders.

When the diver would run low on air, he would pull the lever to access the reserve gas, much like the reserve fuel and fuel switch found on some motorcycles’ fuel tanks.

The cylinders were then secured to a harness that the diver would wear. To control buoyancy, divers would regulate the amount of gas in their lungs, much like fish do with their air bladders. To move shallower, the diver would inhale a large amount of gas, to move deeper; he would exhale as much as possible. To maintain his depth, the diver would inhale and exhale smaller amounts of gas.

The first application of the Buoyancy Compensator Device was more like a life saving collar than anything else. A two to three cubic foot (one-liter) compressed gas cylinder on the diver’s abdomen inflated these devices, and there wasn’t an easy way to remove the gas once the collar was inflated.

Eventually, manufacturers began making devices that attached by a hose to the low-pressure outlet of the first-stage regulator.  While these early BCDs maintained the collar shape, it wasn’t long before manufacturers began refining them into what has become the modern BCD.

There’s no doubt that the BCD was revolutionary for scuba diving. It opened up the sport to those that did not possess the same conditioning or body type as those in the military, and enabled divers around the world to dive more comfortably and confidently than ever before.

The BCD was so impactful to diving that it became a required piece of equipment for scuba diver training.

In fact, the Training Agencies failed in taking full advantage of the arrival of the BCD, instead of changing the training system by exploiting the characteristics of the equipment. They limited themselves to “replacing” the traditional backpack with the (BCD) as support for the tank, but continued to teach the courses keeping the students “on their knees” at the bottom of the pool, it merits noting that it was the only possible way before the advent of the BCD.

SNSI, is the first training agency that in 2019, changed the teaching system of the basic courses and introduced the use of the SNSI Buoyancy Bar System (a bar) that allows the Instructor to teach “as a first basic skill” the use of the BCD and neutral buoyancy. If you have taken an SNSI Open Water Diver course with the SNSI Buoyancy Bar System, you are undoubtedly more advanced in the management and control of your buoyancy than your colleagues who have participated in a basic course with antiquated teaching methods.

Every BCD’s primary function is to enable the diver to precisely control his buoyancy while under water. Beyond that; however, there are a vast number of different BCDs available; each with their own set of features and benefits.

They come in various styles and are built from different materials. There are accessories that allow for the mounting of other pieces of equipment and each varies as to where the gas bladders are located.

In the last decade, many manufacturers have developed back-mounded, or backpack style BCDs in which the bladders are located on the back of the BCD. While this trend came from the increase in technical diving participation, there are still many options — back-mounted, front-mounted, and everything in-between, for the diver to choose from based on their needs and diving style.

Many modern BCDs have integrated weight systems built into the jacket, alleviating the need to wear as much weight on the belt, or the need to wear a weight belt altogether. This is a significant benefit for divers that are prone to misbalanced weight belts due to body type, and those that have difficulty with belt positioning.

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Advanced Open Water Diver