In backmount, the tank is fixed. In sidemount, the tank is a lever. And levers cause rotation.
If you clip a cylinder to your chest D-ring and bottom clip, but the tank's center of buoyancy is behind your center of gravity, you will roll onto your back (feet up, face to the sky). If it is too far forward, you will pitch head-down.
The solution is the Leaning "L" position. When viewed from the side, your tank should angle slightly back—the valve higher than the boot. Typically, a 5 to 15-degree tilt.
In the sprawling, chaotic city of Atherton, where skyscrapers clawed at a smoggy sky and the stock market’s heartbeat was the only rhythm anyone respected, there lived a man named Elias Voss. Elias was a master of a forgotten art: Sidemount Engineering.
Sidemount wasn’t about building taller, grander, or louder. It was about attaching a secondary system—a backup, an alternative, a parallel path—to an existing primary structure. In an age obsessed with singular, monolithic solutions, Elias was a quiet heretic. His motto, stitched above his workshop door, read: “The main engine always fails. The sidemount never steers, but it always lands.”
Elias had three principles for success, carved into his workbench:
For thirty years, Elias applied these principles to elevators, bridge supports, and city power grids. His peers laughed. “Why build two when one good one will do?” they’d say. Elias would smile and point to the sky. “Because the sky doesn’t care about your confidence.”
One autumn, a gleaming new tech conglomerate named OmniCore hired Elias. They had built the “Atherton Artery”—a single, magnetic-levitation train line that would carry 80% of the city’s commuters. It was a masterpiece of efficiency: no sidemount, no backup, just pure, streamlined power. The CEO, a woman named Daria Sol, believed redundancy was failure dressed up as caution.
“Your principles are fear-based, Elias,” Daria said, showing him the Artery’s control room. A single, beautiful crystal tube pulsed with light. “If we build it perfectly, we don’t need a second.”
Elias ran his hand over the tube. “The crystal is flawless. But the human who cleans it will drop a wrench. The rat that chews a wire doesn’t know it’s perfect. Principle One: balance before power. You have all power, no balance.”
Daria fired him on the spot.
Six months later, on a frigid December evening, Elias was in his workshop polishing a small, unassuming sidemount module he’d built for the city’s water pumps. The news flickered on a dusty screen. The Atherton Artery had derailed. Sidemount- Principles For Success
Not crashed. Derailed. A single sensor, the size of a fingernail, had failed. The primary crystal tube overheated by 0.4 degrees. The safety systems, all dependent on that same sensor, never knew to engage. The train carrying 3,000 people had switched to a dead spur line at 200 miles per hour. Emergency brakes were fried. The Artery was a monument to perfection, now a tomb in waiting.
Panic erupted. Daria Sol’s voice on every channel: “We have no backup! There is no sidemount!”
Elias looked at his water-pump module. Then he looked at the schematic he’d secretly drawn two years ago—a sidemount guidance rail for the Artery. He’d never shown it to Daria. But he’d kept it. Principle Two: independent motion.
He grabbed his toolkit and drove to the disaster site. Police had sealed it off. Elias didn’t argue. He walked to the edge of the dead spur line, where an old, decommissioned freight track ran parallel to the Artery’s main line. It was rusted, ignored. But it was there.
For the next fourteen hours, Elias worked alone in the freezing dark. He attached his sidemount module to the stranded train’s undercarriage—a secondary guidance claw, a separate battery pack, and a set of emergency wheels designed to drop onto the old freight track. It was ugly. It was desperate. It was balanced.
At 6:00 AM, with the train’s primary life support failing and rescue helicopters unable to land, Elias climbed to the driver’s cabin. The driver was a young woman named Mira, terrified.
“What is that thing you bolted to my train?” she whispered.
“A second chance,” Elias said. “Listen. Your primary controls are dead. Don’t touch them. I’m going to engage the sidemount. You will feel a jerk. Do not fight it. Let the sidemount steer.”
Mira nodded. Elias pulled a mechanical lever. For three heartbeats, nothing happened. Then—a deep, grinding thunk. The train lurched sideways. People screamed. But the sidemount’s wheels had found the freight track. The guidance claw, running on its own independent battery, began pulling the train—slowly, gently—away from the dead spur.
The silent handoff.
For two miles, the train crawled along the rusted freight line. It was slower than a bicycle. But it was moving. And at the end of that line was a emergency station—unused for decades, but intact. Elias had checked the blueprints years ago. In backmount, the tank is fixed
The train coasted to a stop. The doors opened. Three thousand people stepped onto a cold, dusty platform, shivering, crying, but alive.
Daria Sol arrived an hour later, her face ashen. She found Elias drinking cold coffee from a thermos, sitting on the freight track.
“You saved them,” she said. “How?”
Elias tapped the sidemount module. “Principles for success. Balance before power. Independent motion. The silent handoff. Your primary failed because it had no partner. Success isn’t about never falling. It’s about having something that catches you when you do.”
Daria was silent for a long time. Then she knelt and read the three principles, still stitched on Elias’s dusty jacket.
The next year, every major system in Atherton was redesigned. Not to be perfect. To be paired. Sidemounts appeared on elevators, power grids, and even the mayor’s car. The city never had another catastrophe.
And Elias Voss, the forgotten engineer, became the man who taught a city that the secret to success is not a single, soaring engine. It is the quiet, ugly, faithful sidemount that asks for nothing—until everything depends on it.
"Sidemount: Principles For Success" outlines a methodology focusing on streamlining, stability, and redundancy to master sidemount diving, promoting a minimalist approach to gear configuration. The system emphasizes precise equipment setup—specifically harness and cylinder positioning—along with maintaining perfect horizontal trim for improved comfort and safety in both recreational and technical diving. For further reading, see the Facebook group discussion on Sidemount: Principles for Success Sidemount: Principles For Success (eBook) Feb 5, 2569 BE —
The guide " Sidemount: Principles For Success " by Andy Davis is an authoritative manual focused on achieving optimal configuration, trim, and efficiency in sidemount diving. The following guide outlines the core principles and practical steps derived from this methodology to ensure success with your sidemount setup. 1. Harness & Hardware Configuration
A successful sidemount experience begins with a perfectly fitted harness that acts as a stable foundation for all other skills.
Plate Positioning: The shoulder plate should sit just below the C7 vertebrae (the prominent bone at the base of your neck). The lumbar plate must be positioned very low, over the S2 vertebrae at the flat area just above the buttocks. In the sprawling, chaotic city of Atherton, where
Bungee Systems: The guide emphasizes using loop bungees as the most effective method for maintaining upper cylinder hold. Correct length is critical; when stretched from the rear to the chest, they should comfortably reach the nipples and meet at the sternum under high tension.
D-Ring Placement: Shoulder D-rings should be located immediately below the collarbones to keep connections accessible and above clutter. Waist D-rings are positioned based on the height of your torso to ensure cylinders sit parallel to your body. 2. Mastering "Dynamic Trim"
Achieving a horizontal, streamlined profile (trim) is a hallmark of success in sidemount.
Cylinder Alignment: The biggest mistake is "slinging" cylinders like stage bottles rather than mounting them flush against the sides. For aluminum cylinders, which become more buoyant as they empty, you must iteratively adjust the cylinder clip position to prevent them from floating upwards or rotating inward.
Weight Distribution: Weight should be spread across the harness rather than just on the back to maintain center of gravity.
Stability Foundations: Stability comes from a combination of correct weighting, lung volume use, and perfectly trimmed cylinders. A successful diver can hold their position in the water without using hands or fins. 3. Essential Operational Skills
Once the equipment is dialed in, success depends on standardized procedures and muscle memory. Sidemount diving guide for success - Facebook
In the early 2000s, if you walked onto a dive boat with two tanks strapped to your sides instead of your back, you were considered an outlier—a cave diver who simply hadn't learned how to socialize with "normal" recreational divers. Today, sidemount diving has exploded beyond the sump and the cavern. It dominates technical wrecks, penetrates pristine coral reefs, and is rapidly becoming the configuration of choice for solo divers, photographers, and even warm-water vacationers.
But here is the hard truth: Sidemount is not a short cut; it is a discipline.
Many divers try sidemount once, feel like a barnacle-covered anchor, and declare it "unstable." Others succeed brilliantly, gliding through restrictions with the grace of a fighter jet. The difference between struggle and success is not talent or money. It is adherence to a few immutable principles.
This article deconstructs the sidemount configuration into seven core principles. Whether you are rigging your first set of AL80s or trimming out steel LP85s for a 6-hour cave dive, these laws apply.