A sidemount diving configuration generally consists of two cylinders that are attached to an integrated harness and BC system. The cylinders are attached individually, one on each side of the body, instead of mounted on the back like a traditional open water configuration.
One of the primary advantages of the sidemount configuration is that, by moving the cylinders off of the back, the diver’s vertical profile is lowered when in the diver is in proper horizontal trim. This can allow the diver access to smaller areas inside of a cave or wreck while simultaneously being less likely to damage fragile environments.
However, to achieve these benefits the cylinders must be attached in such a way that they are close to being in line with the body and not hanging too low in front of the diver. For this reason, nearly all modern day sidemount harness systems incorporate some type of bungee cord for the top cylinder attachment point. The bungee serves to keep the cylinder pulled up close to the body, under the armpits, while still allowing some freedom of movement for comfort and to push or pull the cylinders as needed to check gauges or wiggle through a small restriction.
A variety of cylinder attachment methods have been used over the decades, but most current harness manufacturers have converged on the bungee type of system.
Most sidemount systems on the market today use one of 3 types of bungees: independent bungees, ring bungees, and loop bungees. Each style has its pros and cons and it is up to the diver to decide which system works best for them.
Independent Bungees
Independent bungees usually consist of a length of bungee attached to the back of the harness between the shoulder blades. Bolt snaps are attached to the free ends of the bungees. When the cylinder is donned, the bungee is stretched around the neck of the cylinder and the bolt snap is clipped off on a chest mounted D-ring on the harness.
Pros
- They are simple, cheap, and easy to use.
- They have been widely used for many years.
- They can be used with any valves. Matched (left & right hand) valves are not required.
Cons
- They are not “one size fits all”. The length must be tailored to the individual diver for correct tank positioning.
- The cylinders tend to slide down to the chest D-ring and because of this ride lower than when using other styles.
- The bungee is not intended to bear the weight of the entire cylinder, so walking out of the water with heavy cylinders attached can overstress and damage the bungee.
- The bungees can swing behind the diver when not clipped off and be difficult to locate when gearing up.
Ring Bungees
Ring bungees are a Dive Rite exclusive. First introduced in 2010, this style of bungee is similar in appearance to the independent bungee, but includes an additional 2” diameter stainless steel ring attached between the bungee and the bolt snap. The bolt snap is then clipped off to the chest D-ring.
Using this system requires that the cylinder be setup using a stage strap kit with a bolt snap on the top and bottom of the cylinder. A webbing “choker” strap is cinched around the neck of the tank through the top bolt snap to keep it pulled tight against the cylinder.
When donning the cylinder, simply clip the top bolt snap on the stage strap into the 2” ring on the bungee.
Pros
- The weight of the tank is supported by the hardware and not the bungee when out of the water.
- This allows jumping in and walking up ladders with tanks securely clipped on.
- It’s fast and easy to clip the tanks on.
- They are ideal for ocean diving, repelling into cave entrances, or gearing up in water too deep to stand.
- The tank connection is secure and the tank cannot roll out.
- The bungees stay clipped off and are not lost when gearing up.
- It is easy to convert a stage bottle into a primary sidemount tank by adding a choker to the top bolt snap.
- They can be used with any valves. Matched (left & right hand) valves are not required.
Cons
- Additional hardware is required.
- Tanks must be setup with stage straps.
- Tanks may hang lower than with loop bungees.
- For thin chested divers it can be difficult to make the bungees tight enough to hold the tanks in proper position while still being able to access the rings.
- Divers with limited mobility may have trouble accessing the rings.
- Because of the additional hardware, the first stages must be oriented facing down.
Loop Bungees
An evolution of early sidemount systems that utilized loops of bicycle inner tube, loop bungees consist of a simple loop of bungee cord that is attached to the back of the harness between the shoulder blades. The loop is then stretched over the valve handle of the tank. The loop may also be tethered to the chest D-ring using a quick link, bolt snap, or small piece of rope. This keeps the loop in place and easy to locate. An additional safety clip may 
also be tied around the neck of the tank and clipped to the chest D-ring. Proper bungee diameter and stretch is critical to get the most out of this style of bungee. The bungee should be strong enough to support the weight of the tank in the water while stretchy enough to be comfortable and to stretch it over the valve.
Pros
- They are simple, clean, and require minimal hardware.
- With proper loop adjustment, tanks can be kept tighter and more in line with the body—especially with thinner chested divers. This creates less drag, lower profile in the water, and less damage to fragile environments.
- The tanks can be rigged with the first stages facing up, tucked under the armpits. This provides protection for the first stages, and can also allow for cleaner hose routing on the top side of the tanks.
- Loop bungees apply torque to the tanks causing them to rotate in towards the diver limiting side to side movement.
Cons
- An additional safety clip may be needed on the top of the tank in case the bottle rolls out of the bungee. This is especially important for heavier steel tanks.
- It may be more difficult to don tanks when gearing up in water too deep to stand compared to other types of bungees.
- SPGs may be more difficult to access and read if the first stages are oriented on the top side of the tanks.
- Walking out of the water with tanks attached can damage the bungees unless an additional safety clip is used to support the weight of the tank.
Fit and Adjustment
Regardless of the style of bungee used, proper fit is critical to having the cylinders ride in the correct position. Fit is an individual consideration for every diver and involves several factors including exposure protection thickness, cylinder selection, body type, and mobility. This is not a case of one size fits all, and may need to be revisited if cylinder or exposure protection changes are made. Depending on the bungee type, the fit may be adjusted by shortening or lengthening the bungee, changing the attachment points, adding or subtracting additional quick links, or using different diameter bungee.
Dive Rite ABS (Adjustable Bungee System)
To make proper adjustment and customization faster and easier, Dive Rite has released the new ABS—Adjustable Bungee System. ABS bungees consist of a length of bungee woven through a custom designed, laser cut plate. This innovative design allows fast, tool free adjustment of the bungee length. Additionally, they can be easily un-weaved and converted into any of the three styles of bungees listed above. The included ring bungee hardware can be easily removed converting them into loop style bungees. Weave a bolt snap onto the loop and they can now be used as independent bungees.
Click here for more information on the Dive Rite ABS.
