Equipment Considerations for Sidemount Diving
by: Dr. Thomas Powell:
If you are a diver who watches the latest trends, keeps up with new scuba innovations, or just recognizes new things going on in the world of scuba diving, you may have noticed that many divers these days are no longer carrying cylinders on their backs. Instead, some divers have switched to sidemount configurations. In fact, sidemount diving has become so popular that major manufacturers are creating whole new lines of equipment designed to meet the needs of sidemount divers.
What is sidemount diving?
The most common mental image a person develops when thinking of scuba diving involves an individual underwater with a second stage in his or her mouth and a cylinder strapped to his or her back. Sidemount diving is a deviation from this norm. Essentially, cylinders are rigged to the sides of a harness and separate regulator systems are used to supply gas from each cylinder. Situating the cylinders in this fashion allowed early sidemount divers to remove and replace cylinders when the need arose to swim through confined spaces.
In recent years, the recreational scuba community has found benefits associated with sidemount configurations. The first and foremost of these benefits is that the weight of scuba cylinders can be removed from the back. Cylinders can be carried to the water, attached in the water, and later removed prior to exiting the water. Second, a sidemount configuration creates a redundant air source. Two separate cylinders with different regulator systems ensure a redundant air source is available in the case of a major emergency. Dual cylinders also allow for the possibility of carrying a larger gas supply on regular dives. Combined, these factors may allow a diver to extend dive times in a safe fashion within no decompression limits.
As you dive in different places around the world, you may see and encounter cylinders of various shapes, sizes, and volumes. In the realm of sidemount diving, you must choose cylinder options based on what works for you and the type of diving you plan on doing. You may choose to use small steel cylinders that are easy to carry, transport, and manipulate. You may use aluminum 80s because they are common and easy to find anywhere you travel. You may even decide to use large volume steel cylinders purely for gas availability. The reality is that once you find what works for you, you need to go out and practice using these types of cylinders. Cylinders have differing buoyancy characteristics and those characteristics may alter as you dive and consume gas. As divers, we know that these changes require adaptations and planning to ensure fun and safe scuba activities.
Regulators can be a touchy subject. Many divers have brands they love and brands they love a little less. The truth of the matter is that once again you need to find regulators that match your style of diving. Since second stage regulators are going to be delivering gas from both sides of the body, some divers find that they prefer hoses to be routed to the second stages from the side of the body on which the attached cylinders rest. Essentially, one second stage would have a hose input from the left side and one regulator would have a hose input form the right side. Various scuba equipment manufacturers have begun to develop second stage regulators that can be altered to allow hose inputs to come from either side. The idea here is that hoses may require less length (less to tuck away) and a feed from a specific side may reduce discomfort associated with how the second stage sits in the mouth. Similarly, with sidemount diving a cylinder can be handed off to another diver if the need arises, so the need for a long hose may be reduced. Conversely, many divers prefer or enjoy hose configurations and lengths that they have always used and grown accustomed to with other gear configurations. In this case, a long hose can still be routed around the head of a diver allowing second stage hose inputs to both come from the traditional right side.
The growth in popularity associated with sidemount diving has opened the doorway for various manufacturers to develop buoyancy compensator and harness systems designed specifically for sidemount diving. First and foremost, there are rigs designed only for sidemount diving. Systems of this type often have a bladder centralized in the area of the lower back and then have rigging points and/or bungie loops to harness cylinders. These rigs are often small and designed for simplicity and tight trim. Over time, improvements have been made to these types of rigs based on experience from active sidemount divers. Examples of these types of systems can be found in the Dive Rite Nomad LTZ, the X-Deep Stealth 2.0, the Hollis SMS 50, and the SEAC KS10. These are only a few examples of many variations on the market.
Second, there are rigs designed for various types of diving. Essentially, a traditional form of wing is mounted to a harness system designed for sidemount diving. These rigs also allow a diver to carry back-mounted gas as desired by leaving the middle area of the back free of a centralized bladder. Grommets are also typically placed along the spine as needed for tank adaptors. Some examples of these types of systems can be found in the Dive Rite Nomad XT and the Hollis SMS 75 or 100.
Finally, a traditional plate and wing is still a “go-to” versatile system for almost any type of diving. The plate, whether stainless steel or aluminum, provides the base for your system. The various holes and slots provide the avenues to transform that plate into whatever you need. Essentially you can seek out or create whatever type of harness you want. The harness can have quick releases or be a traditional hogarthian harness. Similarly, you can add D-rings, quick connects, bungie, or hardware as needed. A back plate with traditional webbing also allows items such as butt plates or pouches to be added as desired using multiple attachment methods. Systems of this type also allow almost any needed wing to be attached and a diver can choose to dive sidemounted cylinders, doubles, or single tank back gas with minimal alterations.
One last thing to remember is that with sidemount diving, you may be carrying more cylinder weight than normal when compared to single tank diving. You will also be toting a second regulator setup. Added weight, plus the act of moving cylinders to side of the body can alter the trim and buoyancy of any diver. Many manufacturers have developed weighting systems for sidemount buoyancy compensators that allow weight to be mounted behind the diver or in unique locations that offset cylinder weight. Again, practice is what helps any diver improve. Once you figure out what gear configuration you like best, you have to get wet and work to become proficient.
Sidemount diving is a trend that has grown. Divers of all types have begun to find value in this type of configuration and the industry has supported the innovation. Remember that researching, buying, and using sidemount equipment should be treated just like any other scuba-related purchase. Take your time to try out and understand the options available. Once you find what you like, work to become safe and proficient. Then go and enjoy your new method of diving. After all, the whole idea behind altering your current gear configuration is to safely enjoy your time underwater in a new and comfortable fashion that best suits your needs.
– Thomas Powell – Owner/Instructor Trainer – Air Hogs Scuba, Garner, NC