CCR (rebreather) diving equipment: what do you need for safe diving

Closed-circuit rebreathers (CCRs) have expanded the boundaries of what divers can safely explore — deeper depths, longer runtimes, and environments once considered unreachable. But with this advanced technology comes a new level of responsibility: proper equipment selection and preparation.

“Rebreathers are nothing more than tools to allow you to remain underwater for an extended period.”
— Jeffrey E. Bozanic, Mastering Rebreathers (Second Edition)

Tools, however, are only as reliable as the diver who maintains and configures them. This guide focuses on the supporting equipment that ensures your CCR diving is safe, efficient, and fully under control.

In-Water Equipment: Beyond the Rebreather

BCD / Wing System

Unlike open-circuit setups, a CCR diver must be ready for the unlikely — but potentially critical — flooding of the rebreather unit. A fully flooded loop or scrubber can instantly add up to 10 kilograms of negative buoyancy, which must be compensated for by your buoyancy system.

Unfortunately, most manufacturers underestimate the lift required for CCRs, offering wings that are simply too small. Choose a BCD or wing with generous lift capacity, stable geometry, and a durable bladder to remain positively buoyant even if your unit floods completely.

Dive Computers

The Divesoft Liberty CCR is built with full redundancy — dual controllers, dual displays, and dual power supplies. For most dives, that’s all you need. However, many experienced technical divers still carry a Divesoft Freedom computer as an independent backup, especially on expedition-level dives.

The Freedom provides an additional, fully autonomous depth and decompression reference — because in technical diving, redundancy equals safety.

Gas Analyzers

Even for recreational CCR diving, a gas analyzer is an absolutely essential piece of safety equipment. Every diver must personally analyze the gas mixture in their cylinders and verify the actual oxygen and, when applicable, helium content.

As Jeff Bozanic emphasizes, “You must personally analyze or directly observe the analysis of the breathing gas you will be using.” An unknown or incorrectly analyzed mix can lead to hypoxia, hyperoxia, or serious decompression errors.

Beginning CCR divers should at least own a nitrox analyzer, such as the Divesoft DNA.
However, it is better to invest directly in a combined He/O₂ analyzer, such as the Divesoft He/O₂ Analyzer or the more compact Divesoft SOLO.
Even if you start diving with a plain air diluent, you will very soon progress to deeper CCR dives where trimix analysis becomes essential — requiring accurate measurement of both oxygen and helium content.

Fins: Precision and Buoyancy Balance

Fin choice is more than comfort — it directly impacts your trim and propulsion control.
For CCR and technical diving, shorter, wider fins with stiff blades are ideal. They deliver precise feedback for techniques like the frog kick, modified flutter, or back kick, enabling fine positioning without disturbing silt or fragile environments.

Fin buoyancy matters:

• In cold water with a drysuit, heavy rubber fins offset the positive buoyancy of drysuit boots, maintaining a balanced horizontal trim.

• In warm water and wetsuits, heavy fins cause the legs to sink. Choose lightweight or neutrally buoyant fins for a stable, efficient posture.

A well-trimmed diver conserves gas, reduces workload, and optimizes scrubber efficiency — improving both safety and performance.

Surface Marker Buoy (SMB / DSMB)

Every CCR diver should carry a Delayed Surface Marker Buoy (DSMB) — it’s not optional. Without bubbles to mark your position, a DSMB is your only visible link to the surface.

It serves several key purposes:

1. Emergency ascent signaling: alert surface support in the event of an equipment or gas issue.

2. Marking your ascent line: useful in open water or poor visibility where no fixed line is available.

3. Decompression in currents: provides a stable reference point while maintaining your position in moving water.

Choose a high-visibility DSMB (orange or yellow, minimum 1.5 m) and a reliable reel or spool. Practice deployment frequently, including from depth and while neutrally buoyant.

“Evaluate the conditions before every dive; ensure that they fit your personal capabilities.”
— Jeffrey E. Bozanic, Mastering Rebreathers (Second Edition)

For diving to greater depths, you need a rope that is long enough to be able to release a buoy from the bottom or from the deck of a wreck. This is necessary if you lose your bearings and cannot return to the ascent rope.

The only option then is to rely on a line with a buoy. The Divesoft reel is a perfect and reliable choice that will suffice for all conceivable dives. It has saved the lives of many divers in this way.

Bailout Configuration: Your Last Line of Defense

In CCR diving, your bailout system is your true safety reserve — a fully independent life-support system. It must allow you to ascend safely on open circuit, from the deepest and most demanding point of your dive, with all decompression stops completed.

Sizing and Gas Planning

Always plan bailout gas for the worst-case scenario. That means considering depth, decompression time, current, stress, and elevated SAC rates. Bailout gases are for emergencies only and should never be consumed during normal operation.

Experienced CCR divers maintain several bailout cylinders with different gas mixes — typically deep, intermediate, and decompression gases — and select the right combination for each dive.

For example,
— I personally use a total of six different tanks: an air tank for simple dives to 30 m, Helitrox 30/30 for dives to 40 m or as travel/deco gas, 15/60 and 12/80 for great depths, and finally EAN50 and oxygen as decompression mixtures.

Regulator and Hose Routing

Clean routing and reliability are key:

• Hoses should run along the cylinder for a streamlined, snag-free setup.

• Use a swivel turret first stage or angled ports for flexibility and tidy routing.

• The Divesoft Technical Adapter for Apeks DST provides perfect hose alignment for CCR bailout systems.

Additional Utility Connections

A well-equipped bailout first stage can do more than deliver breathing gas.

• An inflator-style quick-connect hose adds valuable versatility:

• Serves as an independent drysuit inflation source if onboard diluent isn’t accessible.
• Can connect to the Manual Addition Valve (MAV) for manual oxygen addition when needed.

• Add high-flow connectors like Swagelok or Omniswivel to connect on-board and off-board gas in case of loss or for complex dive profiles.

This setup ensures full control over loop oxygen and buoyancy — even when operating on bailout gas.

“Failure to plan for bailout is planning to fail. Redundancy is not optional — it’s what keeps you alive when everything else stops working. ” — Jeffrey E. Bozanic, Mastering Rebreathers (Second Edition)

Service and Spare Parts: What Keeps You Diving

A well-prepared diver’s toolkit is as important as the rebreather itself. Having the right parts and tools on hand can turn potential dive cancellations into minor delays.

Recommended Service Kit

• O-rings and seals (oxygen-compatible)

• Spare oxygen sensors, properly calibrated and stored

• Lubricants: oxygen-safe (e.g., Krytox®)

• Tools: hex keys, spanners, O-ring picks, flow meters, IP gauges

• Hoses and valves for O₂, diluent, and bailout systems

• Disinfectants: iodine-based or Virkon S®

• Spare batteries and cables for HUDs, handsets, and analyzers

“Properly caring for equipment after every dive will extend its usable life, preserve its value, and, most importantly, minimize the chance of failure during a dive.”
— Jeffrey E. Bozanic, Mastering Rebreathers (Second Edition)

Divesoft’s Philosophy: Precision in Every Breath

At Divesoft, we believe that safety begins long before you enter the water. From Liberty CCR systems with full redundancy, to Freedom dive computers and gas analyzers, every product is engineered to support your dive with precision and reliability.

Author: Jakub Šimánek