Introduction – Learning CCR the Right Way

Switching from open circuit to a rebreather is one of the biggest steps in a diver’s journey. Technology changes, planning changes, mindset changes — and that adjustment period can create predictable mistakes for new CCR divers.

These are real issues I’ve coached divers through, especially those on the Hollis Prism2, but they apply across all units and training agencies.

1. Complacency With Pre-Dive Checks

The mistake:
New CCR divers sometimes rush or skip parts of their checklist once they’ve done a few dives.
“I packed it yesterday, it’ll be fine.”
“We only changed a small thing; let’s just go.”

Why it matters:
A skipped checklist is the root cause behind a huge percentage of CCR accidents.
Cells, sensors, O-rings, scrubber packing — one oversight can snowball.

How to avoid it:

• Use a written checklist every time (physical or digital).
• Slow down. CCR diving rewards patience.
• Treat the BOV/OC bailout test as non-negotiable.
• Pack and test without distractions.

2. Poor Loop Volume Management

The mistake:
New divers either run the loop too full (bubble-like buoyancy) or too empty (work-of-breathing struggle).

Why it matters:
Loop volume affects:

• Buoyancy
• Trim
• Breathing effort
• Workload on ascent/descent
• CO₂ retention risk

How to avoid it:

• Practice “loop neutral” at different depths.
• Use small, deliberate additions — not big breaths.
• Learn the feel of optimal loop tension early.

On the Hollis Prism2, balanced counterlungs make this easier, but only if your trim is solid.

3. Task Loading Too Early

The mistake:
Trying to run cameras, scooters, extra stages or long routes before core CCR skills are instinctive.

Why it matters:
CCR has a cognitive load:

• Monitoring PO₂
• Loop management
• Setpoint handling
• BOV usage
• HUD awareness
• Bailout readiness

Task loading too early leads to missed warnings, slow response times, and poor buoyancy.

How to avoid it:

• First 10–20 hours: keep dives simple.
• Build camera or scooter skills after buoyancy mastery.
• If you feel behind the unit, slow down, simplify, reset.

4. Overreliance on Automation

The mistake:
New divers trust the computer to “handle everything” — especially on electronically controlled units.

Why it matters:
Automation helps, but you are the life support system.

If you don’t understand:

• What your solenoid is doing
• Why your PO₂ is drifting
• How your sensors are behaving
• What manual mode feels like
  …then you’re not ready to handle failures.

How to avoid it:

• Practice manual PO₂ control regularly.
• Dive different setpoints deliberately.
• Switch modes during training (with instructor).
• Watch trend behaviour, not just numbers.

On the Prism2, the manual mode is intuitive — use it often to build confidence.

5. Forgetting That Skills Fade Quickly

The mistake:
Three months off the unit, two missed dives, and suddenly:

• buoyancy is sloppy
• setpoint awareness is poor
• bailout drills feel alien

Why it matters:
CCR skills are high-consequence.
If you don’t dive regularly, you lose muscle memory fast.

How to avoid it:

• Don’t return to the unit “cold”.
• Book a 1–2 dive CCR tune-up when returning after a break.
• Start again in shallow, controlled conditions.
• Re-do bailout, dil flush, loop checks, OC ascents.

6. Being Unprepared for Bailout

The mistake:
New CCR divers underestimate bailout gas, planning and mental readiness.

Typical issues:

• “I’ll never need this much gas.”
• Incorrect gas choice
• Unrealistic SAC assumptions
• Poor bailout ascent strategy

Why it matters:
Bailout is the ultimate rescue — for you.

If you’re not prepared:

• A minor failure becomes a major problem.
• You may not have the gas needed to get out alive.

How to avoid it:

• Train bailout as if it’s guaranteed, not unlikely.
• Use realistic SAC rates (OC stress rates, not calm CCR rates).
• Run bailout drills at least once every few dives.
• Use a BOV or quick OC access if your unit supports it.

On Wreck & 60–100 m CCR training in Malta, bailout realism is central to every dive plan.

7. Neglecting Unit Maintenance & Servicing

The mistake:
New divers sometimes treat CCR maintenance casually:

• “The scrubber is fine; I didn’t dive long.”
• “O-rings look OK.”
• “I’ll service it next season.”

Why it matters:
Neglect leads to:

• Loop leaks
• Floods
• Sensor issues
• Oxygen spikes or drops
• Reduced reliability

How to avoid it:

• Follow strict scrubber rules
• Replace O-rings proactively
• Service valves and cylinders regularly
• Change sensors on schedule
• Keep the unit dry, clean and correctly stored

Bonus: The Mindset That Prevents 95% of CCR Mistakes

A CCR diver needs to be:

• Calm
• Conservative
• Curious
• Methodical
• Honest about their limits

Not a superhero.
Not a number-chaser.
Just someone who takes the time to do things properly.

This mindset is what keeps CCR safe — and enjoyable — for decades.