How to Properly Rig Your Bottom Mounted Stage Cylinders in Sidemount Diving

Some sidemount divers prefer to carry their stage cylinders below them. The standard stage cylinder rigging used in backmount configuration isn’t optimal because it allows the cylinder to hang too low. This creates drag and makes the entire sidemount system less streamlined. This led to the development of a similar stage rigging as the one I developed for top mounted stage cylinders.

Modifying the Top Mounted Stage Cylinder Rigging
Comparing Top and Bottom
The Solution
Steel vs Aluminum Sidemount Cylinders
Common Stage Rigging Mistakes
Final Thoughts

Modifying the Top Mounted Stage Cylinder Rigging

Some divers couldn’t quite get the hang of securing top mounted stage cylinders to their harnesses. It’s not the easiest skill at first. The benefits of the top mounted stage cylinder rigging were noticed and modifications were made to make it work for bottom mounted stage cylinders. The result was successful.

Comparing Top and Bottom

Bottom mounted stage cylinders had similar issues as the top mounted ones. They just occurred at different times. With top mounted stage cylinders, the bottoms start to rise as gas is breathed from them. With bottom mounted stage cylinders, this rise works well. The issue is that when the stage cylinders are full, the bottoms are negatively buoyant and then hang too low. A method had to be devised to snug the bottoms against the torso while still having enough room to clip the cylinders onto D rings positioned between the sidemount cylinder and the hip.

The Solution

A sliding bungee was created to resolve the issue of the bottom hanging too low. The bungee remains full length during the clipping on and off process. Once secured to the D ring, the bungee is shortened to pull the bottom of the cylinder up against the torso.

Steel vs Aluminum Sidemount Cylinders

When top mounting a stage cylinder, the type of sidemount cylinder you use doesn’t matter. Top mounted stage cylinders push the sidemount cylinder down slightly. Rather than being flush with the front of your torso, they may line up 1 inch/2.5 cm or so below. The clearance is the same. The cylinders are just shifted down slightly.

Bottom mounted stage cylinders have the same affect on aluminum sidemount cylinders, only they push them up slightly. When you see a sidemount diver using aluminum sidemount cylinders and 2 stage cylinders, it might not be possible to tell whether the top or bottom mounting method is being used

Bottom mounted stage cylinders do not have the same affect on steel sidemount cylinders. Steel cylinders maintain enough negative buoyancy that they remain in place. This means the stage cylinder lies a lower.

Common Stage Rigging Mistakes

Stage cylinder riding too low at the bottom
Stage cylinder riding too low at the valve
Bolt snap placement too far from valve
Bungees not proper lengths
Stage cylinder interfering with sidemount cylinders

What if the cylinder doesn’t remain snugged against the torso with this method? Either the worm gear clamp is incorrectly positioned on the stage cylinder or the bungee is too loose.

What if the stage cylinder valve hangs too low? The bungee is either too long or your attachment points on the harness are not in the optimal location.

Final Thoughts

When rigged properly, bottom mounted cylinders can hang snug against the torso and streamlined. Unlike when top mounting, there are some differences when using bottom mounted stage cylinders with steel versus aluminum sidemount cylinders. The big advantage is that they can be used interchangeably.

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How to Choose the Right Sidemount Cylinders
How to Properly Manage Gas in Your Cylinders
How to Choose Proper Hose Lengths
Proper Sidemount Cylinder Rigging: What Matters Most
Proper Sidemount Stage Rigging for Cave Diving
How to Properly Rig Your Top Mounted Stage Cylinder
Common Modifications of the Dive Rite Nomad

For a complete overview of how these elements work together, see The Complete Guide to Sidemount Diving Configuration.