Bailout is the part of CCR diving that gets the least attention on a normal dive and the most attention on the dive that goes wrong. On a closed circuit rebreather, the loop quietly recycles your gas for the entire dive. The bailout cylinders on your back, on your sling, or staged on the team’s frame are sitting there for the moment the loop becomes the wrong place to breathe. The honest answer to “how much bailout do I need” is rarely a single round number. It is a set of decisions that come out of the depth you are diving, how long you are staying, what decompression you owe on the way up, and how the team is set up to support each other.
Silent Diving works with AP Diving Inspiration and Evolution divers across North, Central, and South America, and bailout sizing is one of the most common service-counter conversations we have. What follows is the framework experienced rebreather divers use to make that call, written for divers who already understand the basics of closed circuit and want to plan bailout without guessing.
Why Does Bailout Gas Matter on a Rebreather Dive?
A rebreather is efficient because it reuses the gas you exhale. That same efficiency is why bailout exists. If a sensor cluster argues, a scrubber breaks through, a hose floods, or a controller shows you something you cannot trust, you stop breathing the loop and breathe open circuit instead. Bailout is the gas you carry to do exactly that, on every dive, regardless of how routine the profile looks.
Bailout Is a Plan, Not a Cylinder
Divers sometimes think of bailout as the cylinder clipped to their hip. The cylinder is part of it. The plan is the bigger half. A real bailout plan answers four questions before the diver gets in the water: where could the loss happen, how deep would I be, how much gas does it take to bring me to the surface from there, and what decompression do I owe on the way up. When the answers are written down, the cylinders match the answers.
The broader safety pillars sit alongside this discussion. The piece on sensors, scrubbers, and bailout covers how the three layers of safety work together. This article focuses on the volume question.
The Loop Does Not Always Come Back
One of the assumptions that quietly undercuts bailout planning is the idea that the loop is recoverable. Some loop problems are. Many are not, at least not at depth, in cold water, or in conditions where the diver cannot diagnose calmly. The conservative planning assumption is that once the loop is off, it stays off until the diver is on the surface. Bailout has to be enough for that case.
How Much Bailout Gas Should You Actually Carry?
There are two volumes that matter on a CCR dive: the volume needed to get you off the bottom and onto your decompression plan, and the volume needed to do the rest of the deco on open circuit if the loop never returns. Bailout sizing is the sum of those two volumes, plus reserve.
Start From the Worst Case Loss Point
The starting assumption is that the loss happens at the most expensive point in the profile. For most dives, that is the deepest point or the start of decompression. From there, you need to cover the ascent, every required deco stop, and the surface swim. The reason we plan from the worst case is simple: if the gas covers the worst case, it covers every easier case too.
Use Honest, Stress-Adjusted SAC Rates
Open-circuit SAC rates that are normal for routine dives are usually too optimistic for bailout. A stressed diver who just came off the loop is breathing harder, not lighter. Most experienced CCR instructors plan bailout SAC well above the diver’s relaxed open-circuit SAC. The exact multiplier varies by training agency and personal data, but the principle does not. Use your own measured stressed SAC, not your best dive day on holiday.
Carry Reserve, Not Just Calculated Volume
Bailout is not a “use it all” plan. There needs to be reserve at the surface, so the team has options if a stop ran long, a regulator free-flowed, the surface support is delayed, or a second problem appeared on the way up. Reserve is calculated, not estimated. A sensible reserve gives the diver and the team room to handle the second small thing that goes wrong while the first one is being fixed.
How Do Depth, Runtime, and Decompression Change the Math?
The same diver on the same rebreather needs very different bailout volumes depending on the dive. Bailout sizing is not a single number you carry forever. It is a calculation you redo when the profile changes.
Depth Multiplies Everything
At twice the depth, every breath uses roughly twice the gas. A bailout volume that is comfortable at sixty feet is not comfortable at one hundred and twenty. Divers who add depth without adding bailout are quietly running thinner reserves on every step deeper. The cylinder that worked on a shallow check-out dive will not cover a deep technical profile.
Runtime and Decompression Add Time, Not Just Depth
Long bottom times on rebreathers are part of why divers buy them in the first place. The trade is decompression. A loss at the start of a long decompression obligation is a long open-circuit ascent, sometimes thirty minutes or more on the last set of stops. Bailout has to cover all of it. The post on dive planning, gas, and decompression walks through how bottom time and decompression interact on CCR.
Trimix and Multi-Gas Profiles Need Multiple Bailouts
Single-cylinder bailout is reasonable on shallow recreational CCR profiles. Once decompression involves richer mixes for the shallow stops, bailout becomes a stack: one bottom mix to get out of the deep section, one or more decompression mixes for the stops. The cylinder count grows with the dive, not with the diver’s preference.
Cold Water and Long Surface Swims Are Real Costs
A bailout calculation that ignores the swim back to the boat or shore underestimates total demand. Cold water raises gas usage. A long surface swim on open circuit after a problem at depth is part of the dive, and the plan has to include it. Divers who only train in warm water sometimes forget that the same numbers do not survive a winter quarry trip without revision.
How Should a CCR Team Plan and Carry Bailout?
Solo bailout and team bailout are two different planning models. They are not interchangeable, and the math is different in each. The platform you dive matters less than the planning model the team has agreed to.
Solo Bailout Is Simple and Conservative
A solo bailout plan assumes nobody is going to share gas, and the diver is responsible for every breath of the open-circuit ascent. The cylinders carried have to cover everything. Solo bailout is the simplest model to plan and the heaviest to carry. It is also the only honest model to plan when team discipline is unproven.
Team Bailout Is Lighter but Demands Discipline
A team bailout plan splits the obligation. Two CCR divers on the same profile can plan to share bailout if one of them loses the loop. The total gas carried by the team is less than two solo plans. The discipline is what makes it work: matched profiles, pre-planned positioning, clear hand signals, rehearsed gas-sharing technique, and the willingness to actually call the dive when the team breaks. A team plan with no rehearsal is not a team plan.
Same-Profile Discipline Is Non-Negotiable
The team plan only works if the team is actually on the same profile. Divers drifting apart on depth or runtime quietly turn a team plan back into a solo plan, except now nobody has the gas they thought they had. The post on dialing in weight and trim covers part of why staying together is harder on CCR than people expect, and why a sloppy buoyancy day affects bailout planning long before it affects anything else.
Bailout Configuration on AP Diving Inspiration and Evolution
The AP Diving Inspiration and Evolution platforms are designed to be flown with side-mounted or back-mounted bailout configurations. The platform is flexible. The training and the planning are what make a configuration safe, not the platform itself. Cylinder mounting changes trim. Two stage bottles change trim more than one. The dial-in passes after a configuration change are part of the plan, not optional.
Bailout regulators, decompression regulators, and first-stage seats need to be in current service. A bailout cylinder you cannot breathe from is a worse problem than a cylinder you forgot to carry, because it shows up at the moment of loss. Routine service is on AP Diving’s published service schedule for a reason. Silent Diving’s authorized service covers the chassis and electronics for AP Diving Inspiration and Evolution units in the Americas, and the authorized dealer network is the right starting point for configuration questions.
Frequently Asked Questions
How is bailout different from open-circuit reserve gas?
Open-circuit reserve gas on a non-rebreather dive is the cushion at the bottom of your tank. Bailout on a CCR dive is the entire ascent plan if the loop is unavailable. Reserve answers the question “what if I cut it close.” Bailout answers the question “what if the loop never comes back.”
Should I carry bailout on every CCR dive, even shallow ones?
Yes. The depth at which a loop loss becomes survivable without bailout is a depth nobody seriously dives. Even on shallow recreational CCR profiles, a bailout regulator and cylinder is part of the kit, sized to the profile. The cylinder gets smaller on shallow dives. It does not disappear.
Is one big cylinder enough, or do I need multiple smaller ones?
It depends on the dive. One cylinder can work for shallow profiles with short or no decompression. Multi-gas profiles, deeper trimix, and long decompression usually need a bailout stack with the right gas at the right depth. The decision follows the dive plan, not personal preference.
How does cold water change my bailout plan?
Cold water raises gas consumption, raises the chance of a free-flow on a regulator that was not service-current, and makes ascents slower. A bailout plan that was comfortable in tropical water needs to be rechecked before it is used in cold-water profiles. The same is true after a long surface interval in heavy current or surge.
Can my buddy and I share one bailout plan?
Only with a rehearsed team plan, matched profiles, and gas-sharing skills that have been practiced recently. A team plan in a dive brief is not the same as a team plan executed in the water. If the team has not rehearsed the actual gas-sharing, plan as solo and carry the heavier bailout.
What happens to bailout planning if the dive profile changes underwater?
The plan changes. Going deeper, longer, or skipping a stop changes the bailout obligation. Most CCR teams build a small set of “what if we extend” rules into the brief so the bailout plan stays valid even when the profile slides. If a profile change moves outside those rules, the dive ends and the team comes up.
Where does Silent Diving fit into my bailout setup?
Silent Diving is the authorized distributor and service center for AP Diving Inspiration and Evolution units in North, Central, and South America. We help divers source bailout cylinders and accessories, route service for first stages and chassis, and connect with the authorized dealer for region-specific configuration advice. The authorized dealer network is the right starting point for configuration questions, and the service team handles maintenance and authorized work directly.
Bailout sizing is not the most exciting part of a CCR diver’s preparation, but it is the part that decides how the dive ends if the loop fails. If you are putting a new dive plan together, refreshing your configuration, or planning a deeper or longer profile than your last bailout numbers were built for, talk to your dealer or the Silent Diving service team before the trip. The conversation is faster than rebuilding the plan in the water.
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