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Category: Questions
Questions asked about technical and rebreather aspects of diving
Gas Planning for Deep Wrecks in Malta: Deco Gases, Trimix, and CCR Considerations
Introduction – Gas Planning Is the Real Technical Skill
Malta has some of the world’s most accessible deep wrecks: HMS Stubborn (~55 m), Southwold bow & stern (68–73 m), Schnellboot, ORP Kujawiak, and several 90–100+ m sites for expedition-level CCR diving.
The difference between a safe dive and a stressful one is almost always gas planning
This guide breaks down high-level gas planning principles for deep Malta wrecks — not a full maths class, but a practical framework you can apply immediately.
1. Why Gas Planning Is Different in Malta
Malta’s deeper wrecks create a unique environment:
✔ Consistent depth ranges
Most major wrecks sit at clean, flat depth bands (55 m, 70 m, 90–110 m).
This makes gas planning predictable — if you know the profile.✔ Blue-water ascents
Many wrecks require DSMB ascents with mid-water deco.
Gas planning must allow for imperfect line work or current.✔ Long runtimes
A “short” 70 m dive can still involve 45–70 minutes of deco.
OC gas adds up fast.✔ Perfect for CCR
Deep, square profiles are exactly where CCR shines — but bailout planning must be realistic.
2. Trimix Basics for Malta – Simple Rules That Work
Trimix gas planning isn’t about chasing perfect numbers. It’s about:
- Function
- Safety
- Cognitive clarity
- Logistics
A simple way to think about deep wreck mixes in Malta:
For 45–55 m wrecks (Stubborn / Polynesien deeper routes)
Typical back gas:
Trimix 21/35 or 18/45Why:
- Good END
- Low narcosis
- Moderate helium cost
For 60–70+ m wrecks (Southwold, Schnellboot)
Typical back gas:
Trimix 15/55 or 12/60Why:
- Keeps END sensible (25–30 m range)
- Enough helium to avoid dense gas issues
- More stable physiology during long bottom times
For 90–100+ m dives (Kujawiak / deeper project dives)
Typical back gas:
Trimix 10/70, 8/80 or expedition mixes depending on PO₂ ceilingWhy:
- Very low nitrogen
- Very low gas density
- Narcosis management becomes critical
These aren’t rules — they’re starting points.
Exact mixes depend on:- Workload
- Diver experience
- Unit (OC vs CCR)
- Thermocline
- Dive objective
3. Choosing Deco Gases – Keep It Simple, Keep It Useful
New technical divers often over-complicate deco gas choices.
For typical Malta profiles, these cover 90% of use cases:
✔ Nitrox 50 (50% O₂)
Used from ~21 m
Excellent “workhorse” gas for 45–60 m dives.✔ 80% O₂ or 100% O₂
Used from 6 m
Pure O₂ is great when conditions allow stable holds.✔ Trimix Deco (rarely needed)
For extremely deep or cold dives.
Most Malta divers won’t need it until 90+ m projects.For OC:
- 1 deco gas → Tec40
- 2 deco gases → Tec45 / Tec50 / Trimix
- More only for extreme runtimes
For CCR:
Deco gases are bailout gases first, deco gases second.
4. OC vs CCR Gas Planning – The Real Differences
Most recreational or early-tec divers think CCR is “just more bottom time”.
The real difference is deeper:Open Circuit Trimix – Gas Planning Realities
1. High gas consumption at depth
A 70 m dive on OC burns through:
- Back gas rapidly
- Deco gas rapidly
- And doubles or triples costs
2. Heavy bailout dependence
Your entire plan must assume OC bailout as your exit strategy.
3. Deco gas logistics matter more
If you lose one deco gas, what’s your plan?
OC divers need redundancy at multiple levels.4. Depth/time trade-offs
Want more time?
Prepare for more helium cost and more deco.CCR – Gas Planning Realities
CCR fundamentally changes the profile:
1. One-third to one-tenth the gas cost
Your helium lasts many dives, even at 70–90 m.
2. Deco becomes more efficient
Constant optimal PO₂ reduces decompression.
3. Predominant risk = bailout planning
Your loop gives efficiency.
Your bailout plan gives safety.4. Bottom time flexibility
You can extend the dive safely — but tasks & thermal load still matter.
5. CCR Bailout Planning – The Critical Skill
Many new CCR divers fail at the realistic part of bailout planning:
They plan bailout for calm, perfect conditions – not real ones.
A good CCR bailout plan assumes:
- Stress SAC, not CCR SAC
- Delay before ascent
- Potential current
- Possible deeper start point
- Gas switch issues
- Team separation
- DSMB ascent, not a shot line
For a typical 70 m Malta wreck, bailout might include:
- Deep bailout (e.g., 15/55 or 12/60)
- Nitrox 50
- Oxygen
- BOV access
- Clear switch protocols
6. Example Planning Differences – 70 m Wreck Dive
Not a dive plan — just a comparison.
Open Circuit Example (Southwold Stern, 73 m)
Bottom gas: Trimix 12/60
Deco gases: 50% and 100%
Bottom time: 20–25 min
Total gas carried: 3–4 cylinders
Typical deco: 60–90 min
Primary concern: Gas volume and gas densityCCR Example (Prism2, same wreck)
Diluent: Trimix (e.g., 10/70 or similar)
Setpoints: 1.2–1.3 at depth / 1.4–1.5 ascending
Bottom time: Often 30–40+ min
Bailout: 1–3 cylinders depending on training & team
Deco: Shorter, more controlled
Primary concern: Bailout management & loop disciplineBoth are valid.
CCR simply opens more time and reduces cost.7. Safety Margins – The Most Important Aspect
Gas planning isn’t about minimums.
It’s about margins.A solid plan includes:
- Accurate SAC
- Realistic stress response
- Failure scenarios
- Lost gas contingency
- Team resources
- Ascent strategy
- DSMB plan
- Thermal/physiological load
This is what separates a deep technical dive from a deep number-chasing dive.
Final Thoughts – Gas Planning Is a Skill, Not an Equation
Technical diving isn’t about chasing the perfect mix.
It’s about making decisions that keep you safe, efficient and focused on the wreck — not your SPG.Whether you choose OC trimix or CCR, the principles remain:
- Plan with honesty
- Leave margin
- Prepare bailout properly
- Avoid task overload
- Don’t rush depth progression
Malta offers the ideal environment to train these skills — predictable depths, real wrecks, and clean progression from 40 m to 100+ m.
My journey so far.
My Journey to Tec CCR 100 in Malta
From Stoney Cove and Dorothea Quarry to 100+ metres on a Hollis Prism2
If you’re reading this, you’re probably an experienced diver thinking about going deeper – into technical diving, rebreathers, or both.
I’m Jason Trott, a Tec & Rebreather Instructor based in Malta, with 500+ hours on the Hollis Prism2 and thousands of logged dives. I didn’t start out on trimix in the Mediterranean – I started as a 12-year-old kid in Egypt, completely hooked after my first Red Sea dives.
This is the story of how I went from junior diver in Egypt, through cold Stoney Cove weekends, to 106 m in Dorothea Quarry, and eventually to achieving PADI Tec CCR 100 in Malta at 27 – very likely one of the youngest to do it.
I’m writing it from my perspective so you can see what a realistic path into technical and CCR diving actually looks like, with all the plateaus, cold water, and quarry hours included.
Early Days: Getting Hooked in Egypt (2007)
I made my first dives in the Red Sea in Egypt in 2007, at age 12. Warm water, good viz, colourful reefs – the usual story – but for me it clicked hard. I went back to the UK completely addicted.
Back home, I did what a lot of keen young divers do: pushed right up against the age limits.
- Trained up through the junior levels as quickly as I could.
- Reached Junior Master Scuba Diver while still too young to do half of what I wanted.
- Spent a lot of time waiting for birthdays so I could sign the next bit of paperwork.
By 18, the second the age restriction allowed it, I was:
- Divemaster
- Tec 40
- On a clear path toward deeper, longer, more complex dives.
Stoney Cove, UK – My Real Training Ground
Most of my real development didn’t happen on holiday; it happened at Stoney Cove in the UK.
If you’ve dived there, you know it’s not glamorous – cold water, limited viz, and a lot of repetition – but it’s an excellent environment for building discipline.
At Stoney Cove I:
- Cemented my core skills: buoyancy, trim, gas management, valve drills.
- Worked my way through Tec 40 and Tec 50.
- Got comfortable being cold, wet, and doing the same skills over and over until they were boring – which is exactly the point.
Looking back, those weekends in a quarry did more for my technical diving foundations than any single warm-water trip. If you’re reading this from the UK thinking “I only have quarries” – that’s not a limitation, it’s a training asset.
Dorothea Quarry – First 100 m+ Dives (Max 106 m)
From Stoney Cove, the natural progression for deeper training in the UK is places like Dorothea Quarry in North Wales.
Dorothea has a reputation: deep, cold, overhead rock walls, and plenty of ways to get things wrong if you’re not prepared. It was an obvious step once my training and experience allowed it.
I’ve dived and explored Dorothea to a maximum depth of 106 m.
Those dives were significant for me because they weren’t just about “touching 100 m”:
- They forced serious gas planning and bailout strategy.
- They tested team discipline under real narcosis and deco stress.
- They showed me very clearly where I wanted more redundancy and efficiency – which is where rebreathers started to make more and more sense.
At that point I knew my long-term objective: HMS Britannic at around 120 m. To do that safely and repeatably, CCR wasn’t optional – it was the logical next step.
Why I Moved Into Rebreathers
The push towards rebreather diving was simple:
- I wanted to spend more time on deep wrecks without carrying a ridiculous amount of open-circuit gas.
- I wanted better gas efficiency and a more controlled decompression environment.
- I had specific goals – like Britannic – that realistically require CCR if you want proper time on the wreck.
Open circuit taught me discipline and respect for depth. But for the kind of 120 m-class dives I was interested in, CCR offered:
- Constant best mix at depth.
- Huge reduction in open-circuit gas logistics.
- The ability to treat deep wreck projects as repeated, sustainable dives, not once-in-a-lifetime stunts.
Moving to the Hollis Prism2 (2020)
In 2020 I made the move onto the Hollis Prism2.
I didn’t just want to dive the unit; I knew early on that I wanted to teach on it, so I approached it as a long-term platform, not a toy.
Since then I’ve:
- Logged 500+ hours on the Hollis Prism2.
- Progressed through training all the way to PADI Tec CCR 100.
- Qualified as a PADI Tec Instructor and PADI Rebreather Instructor on the unit.
- Built a lot of those hours specifically on wreck and technical profiles, not just shallow bimbling.
The Prism2 has become the backbone of my diving life, from UK quarries to Red Sea walls to deep wrecks in Malta.
Red Sea and Malta – Warm Water, Real Dives
While a lot of my foundational skills were built in cold UK water, I’ve returned to the Red Sea multiple times and spent extensive time in Malta.
Red Sea
In Egypt and the wider Red Sea I’ve:
- Logged numerous recreational and technical dives on reefs and wrecks.
- Used the clear water to focus on refining trim, buoyancy and situational awareness without fighting cold and low viz.
- Enjoyed that contrast between holiday diving and the more serious project-style dives elsewhere.
Malta
Malta is where everything came together for me.
Malta offers:
- Shallow wrecks and training sites from around 5–20 m.
- Classic tec wrecks in the 40–60 m range.
- Serious deep wrecks out towards 100+ m.
It’s one of the few places where you can realistically build a progression from your first tech steps to genuine expedition-style CCR dives, all from the same base.
That’s why I’m now based in Malta and focusing my Tec and CCR training here.
Working With Different Dive Centres and Teams
I’ve been lucky to work with and around a number of different operations over the years. That mix has given me a wide view of how different teams approach technical and CCR diving.
I’ve worked with:
- DiverCity
- Platinum Divers
- Rec2Tec Diving
- Blue Ocean Diving
- Waterworld Malta
Each centre has its own approach and culture, and spending time with different teams has helped me:
- See multiple ways to solve the same problems.
- Learn from other instructors’ successes and mistakes.
- Refine my own teaching style and standards.
In the next season, I’ll be diving with Divewise / Techwise Malta, continuing to focus on Hollis Prism2 CCR training and technical wreck diving around the islands.
Achieving PADI Tec CCR 100 in Malta at 27 (June 2022)
A key milestone for me was achieving PADI Tec CCR 100 status in Malta in June 2022, at 27 years old.
Given how new rebreathers still are for a lot of divers, that makes me very likely one of the youngest Tec CCR 100 divers at the time – and quite possibly the youngest at 27. I’m not claiming any official world record, but it’s a detail that gives people an idea of how early and intensely I committed to this path.
Tec CCR 100 isn’t just “another card”:
- It formalises 100 m+ rebreather capability with serious decompression.
- It requires real planning, discipline and bailout preparation, not just skill demos.
- It demands a solid track record of CCR dives, problem-solving and team behaviour before you ever see the assessment dives.
Doing that in Malta, on a Hollis Prism2, using the same wreck environment I now teach in, means my current courses are built on exactly the kind of dives my students eventually want to make.
My Teaching Style: Calm, Methodical, Safety-Driven
All of this history feeds into how I now teach Tec and CCR.
A few key points about how I work:
- I’m calm and methodical – no shouting, no theatrics, just clear expectations and repetition.
- I focus relentlessly on margins – we don’t plan to the limit of what’s theoretically possible; we plan to leave room for the unexpected.
- Bailout is central – gas volume, gas choice, realistic loss-of-loop scenarios, and how you and your buddy actually get out alive, not just on paper.
- Team behaviour is non-negotiable – communication, positioning, role clarity and honest pre-dive checks, especially on CCR.
- My background in IT and Open University teaching means I’m used to breaking complex systems down into logical steps and teaching adults who ask hard questions.
My ideal student is not the thrill-seeker chasing numbers. It’s the experienced diver who wants to go further but understands that progression takes time, discipline and honest self-assessment.
Why This Journey Matters If You Want to Train With Me
When you choose an instructor for technical or rebreather training, you’re not just buying a syllabus – you’re buying into their experience, biases and habits.
Here’s what my path means for you:
- I’ve seen both warm and cold water environments – from Red Sea to Stoney Cove to Malta – and I understand how skills translate between them.
- I’ve done the hard quarry hours, not just the photogenic dives, and I still believe in that kind of foundational training.
- I know what it feels like to be at 100+ metres in a dark, cold quarry and on deep wrecks – and I respect that environment.
- I’ve worked with multiple centres (DiverCity, Platinum Divers, Rec2Tec Diving, Blue Ocean Diving, Waterworld Malta, and soon Divewise/Techwise Malta), so my standards are built from a wide base, not a single “house style”.
- I reached Tec CCR 100 at 27, but I did it with conservative planning, not shortcuts. That same mindset applies to every course I run.
Thinking About Tec or CCR Diving in Malta?
If you’re considering:
- Moving from advanced / rescue level into your first Tec course.
- Taking your open-circuit tech experience onto a Hollis Prism2.
- Building towards 60–100 m wreck dives in Malta in a structured, realistic way.
Then this is exactly the environment I’ve built my training around.
On this site you’ll find:
- Details of my PADI Tec 50 and PADI CCR 40 Hollis Prism2 courses (with CCR 60 coming soon).
- Information on the Malta wrecks we use at different stages of training.
- More articles breaking down bailout planning, course structure, and how to prepare before you arrive.
If you’d like to talk through your experience and goals, use the contact form or message me directly. I’ll tell you honestly whether you’re ready, what you need to work on, and how we can build a safe, realistic training plan that moves you towards the dives you actually want to do – not just another plastic card.
– Jason Trott, Tec & Rebreather Instructor, Malta
Beginner’s Guide to the Hollis Prism2: What New CCR Divers Need to Know
Introduction – Why the Hollis Prism2?
The Hollis Prism2 rebreather has become one of the most respected closed-circuit systems for technical divers looking to progress safely into deeper, longer and more efficient dives. Whether you’re moving beyond Tec40/Tec45 or looking at your first CCR, the Prism2 offers a stable, predictable platform for real technical progression.
1. What Exactly Is the Hollis Prism2?
The Hollis Prism2 (often written as Prism 2 or P2) is a rear-mounted closed-circuit rebreather (CCR) built for serious technical diving. It’s widely used for:
- Deep wreck diving
- Trimix exploration
- Long-range project dives
- Progressive CCR training
Key features that matter to new divers:
- Back-mounted counterlungs → familiar balance for divers coming from twinsets
- Solid, predictable control system → excellent for newer CCR divers
- Modular design → easy travel, simple servicing, clean layout
- Stable work-of-breathing → important at depth, especially 60–100 m
- Wide training support through PADI, TDI, RAID and instructors worldwide
The Prism2 is not a gimmick or a trendy unit – it’s a workhorse. That’s why so many technical divers choose it as their first CCR.
2. Who Is the Prism2 Ideal For?
While anyone with the right prerequisites can train on it, the Prism2 is especially well suited for:
✔ Technical divers already using twinsets
The balance and trim feel familiar.
✔ Divers planning 50–100 m progression
The unit handles serious depth very well.
✔ Wreck divers
Rear-mounted lungs keep the chest area clear for valve access and stage management.
✔ Divers who value stability and predictability
The Prism2 focuses on reliability, not endless configuration options.
✔ Divers who want a long-term platform
It’s not something you “outgrow”. It scales from CCR40 all the way to CCR100 and expedition profiles.
If your long-term goals include deep wrecks in Malta, 100 m class dives, or eventually projects like Britannic, the Prism2 is a smart choice.
3. How Does Prism2 Training Work? (Clear Overview)
Prism2 training follows a structured, modular path. Most divers progress through the following:
CCR40 – First Step Onto the Unit (30 m)
Learn:
- Loop management
- Basic failures
- Bailout
- Buoyancy & trim with a CCR
- Setpoints, oxygen control, scrubber management
Perfect for divers transitioning from OC Tec40/45.
CCR60 – Moving Into Real Technical Depth (up to ~60 m)
You’ll learn:
- Deep CCR procedures
- Decompression strategy
- Advanced bailout planning
- Team protocols on CCR
This is where CCR “clicks” for most divers.
CCR100 – Full Technical Depth Capability (100 m+)
Serious training for serious dives.
Skills include:
- Hypoxic trimix
- Complex bailout
- Long decompression profiles
- Realistic failure management
- Deep wreck task loading
Jason completed Tec CCR 100 on the Prism2 in Malta at 27, giving you an instructor who has actually taken the unit to those depths.
4. Why Malta Is an Ideal Place to Learn the Prism2
Malta offers one of the best CCR training environments in the world:
Perfect depth progression:
- 5–20 m → drills
- 30 m → CCR40
- 40–60 m → CCR60
- 70–100+ m → CCR100
Stable conditions:
Predictable viz, minimal currents, ideal for multi-day courses.
Real wrecks at every level:
- Le Polynesien (OC/CCR 40–55 m)
- HMS Stubborn (~55 m)
- Southwold bow & stern (68–73 m)
- Deeper 90–110 m wrecks for post-cert progression
CCR divers need repetition without weather disruption – Malta delivers.
5. Common Questions New Divers Ask About the Prism2
“Is the Prism2 safe for beginners?”
Yes. It’s one of the most stable units on the market. Safety depends far more on discipline than what unit you choose.
“How hard is the transition from open circuit?”
Most divers say the first 5–8 hours feel strange.
After 2–3 days, buoyancy begins to feel natural.
By the end of CCR40, you will feel in control.“Is maintenance difficult?”
You will learn:
- Pre-dive checks
- Packing the scrubber
- Cell management
- Loop testing
- Basic O-ring care
The Prism2 is logical and clean, not fiddly.
“Do I need a lot of bailout cylinders?”
Depends on depth.
For CCR40/60, usually one stage + optional pony.
For CCR100 and deeper wrecks, you’ll carry multiple.Bailout planning is a core part of Jason’s training.
“Is CCR cheaper than OC?”
Upfront = more expensive.
Long-term = dramatically cheaper on helium and logistics.Most divers moving to 60–100 m save a fortune.
6. Why I Specialise in the Hollis Prism2
I’ve trained, logged and taught on multiple systems, but the Prism2 is my primary platform because it offers:
- Stability at depth
- Predictability when problem-solving
- Rear-mounted counterlungs ideal for wreck diving
- Clean, logical maintenance
- Strong global support network
- A training pathway that scales to serious expedition diving
I’ve logged 500+ hours on the Prism2 and achieved Tec CCR 100 on this unit here in Malta. My training is built on the exact progression I used myself.
My focus is simple:
Give divers a safe, realistic and enjoyable path into real-world CCR diving — not just a card.
7. Is the Hollis Prism2 Right for You? (Quick Checklist)
You’re a strong candidate if you:
- Are comfortable with twinset/DIR-style skills
- Want to dive below 50–60 m
- Want more bottom time, less helium cost
- Enjoy the discipline of technical diving
- Are interested in deep wreck exploration
- Want one platform for the next decade of diving
If that sounds like your long-term path, the Prism2 is an excellent choice.
7 Common Mistakes New CCR Divers Make (and How to Avoid Them)
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.
Should I Go Trimix or Rebreather First? A Practical Guide for Technical Divers in Malta
Introduction – The Big Fork in the Road
Once you’ve completed PADI Tec40 or Tec45, you’re standing at the same crossroads every technical diver eventually faces:
Do I continue on open circuit and go trimix?
Or should I move onto a rebreather (CCR) now?Most divers don’t know which path fits their long-term goals. This guide breaks it down based on real experience in Malta’s wreck environment.
Why This Question Matters
Both trimix and CCR are incredible tools – but they serve different purposes.
The right choice depends on:
- Your goals
- Your budget
- How often you plan to dive
- Whether you want to build towards 100 m+ wreck dives
- How much you enjoy equipment and planning
Let’s break it down into the realities, not the marketing.
Option 1 – Go Trimix First (Open Circuit)
What It Is
Trimix training continues your OC journey into deeper and safer profiles by replacing nitrogen with helium.
Typical depth ranges:
- Tec50 Trimix: ~50–60 m
- Full Trimix: 70–100 m+
Why Choose Trimix First
1. You build problem-solving discipline
Open-circuit trimix forces you to:
- Track multiple gases
- Plan bailout precisely
- Handle failures with increasing decompression
- Maintain rock-solid buoyancy under narcosis reduction
It builds strong mental discipline for later CCR work.
2. Zero new life-support systems to learn
You stay with what you know:
- Twinset
- Stages
- Gas switches
- Existing protocols
This removes cognitive load compared to jumping straight into a rebreather.
3. Ideal if you dive only a few big trips a year
Trimix is straightforward for:
- Malta holidays
- Red Sea trips
- Occasional deep wreck missions
You don’t lose currency like you might on CCR if you take long breaks.
4. Cheaper upfront
No unit purchase, no electronics. Just:
- Twinset + regs
- Two stage cylinders
- Trimix training
Much lower barrier to entry.
Limitations of Trimix
- Gas costs add up, especially 60–90 m
- You’re carrying a lot of cylinders
- Short bottom times compared to CCR
- Logistics are heavy for multiple deep dives in a week
Trimix is amazing, but at some point you hit its practical ceiling.
Option 2 – Go Rebreather (CCR) First
What It Is
A rebreather recycles your gas, optimises PO₂ and dramatically improves efficiency.
You’re specifically training on the Hollis Prism 2 CCR.
Why Choose CCR First
1. Much longer bottom times
On a 70–90 m wreck, you can spend:
- Twice as long (and often more)
- With manageable deco
- Without mountains of OC gas
This is the biggest reason divers move to CCR early.
2. Huge gas savings
You’re not burning trimix every minute – you’re recycling it.
This makes deep diving far more affordable long-term.3. Reduced narcosis
Running a consistent high PO₂ means you stay sharper at depth.
Less low-viz “fog”, better awareness.4. Real progression to expedition-level diving
If you ultimately want to dive:
- HMS Southwold (70–73 m)
- HMS Stubborn (~55 m)
- Schnellboot (~65+ m)
- ORP Kujawiak / HMS Oakley (~100 m class)
- Or eventually Brittanic (120 m)
…CCR is the platform.
5. Modern training is safer and more structured
The Prism 2 is one of the most stable, predictable units for new CCR divers.
Training focuses on:
- Loop failures
- Bailout
- Realistic problem-solving
- Team behaviour
Not on “unit tricks” or shortcuts.
Limitations of CCR
- Higher upfront cost
- Electronics require discipline
- You must stay current
- More time spent maintaining the unit
- Bailout needs to be taken seriously
CCR requires a mindset shift – but for many divers it becomes their main tool for life.
Trimix vs CCR – Which Path Fits Your Goals?
Here is the straightforward comparison:
If your goals are 40–55 m wrecks, a few trips per year → Trimix first
You’ll benefit from:
- Simple logistics
- Strong OC skill refinement
- Lower initial investment
Perfect if you’re still exploring the idea of tech.
If your goals are 60–100 m wrecks → CCR first
You’ll benefit from:
- Longer bottom times
- Lower helium costs
- Greater capability and stability
- A platform you can grow with for years
If you know you want deep wreck experience, go CCR early.
If you’re not sure yet → Do Tec40/Tec45, then decide
Tec40 + Tec45 give you:
- Full foundations
- True deco experience
- Team protocols
- Gas switch discipline
You’ll know after Tec45 whether OC trimix or CCR excites you more.
What I Recommend as an Instructor (Realistically)
After 500+ hours on the Hollis Prism 2 and thousands of OC dives:
Best progression for most divers aiming beyond 60 m:
- Twinset + Intro to Tec
- Tec40 + Tec45
- Move to CCR (Prism 2)
- CCR 40 → CCR 60 → CCR 100
- Optional: OC trimix as a cross-training tool
This gives you:
- Strong OC discipline
- Early CCR experience
- A safe path to serious wreck diving
- The ability to do long deep dives properly
This is the pathway I used myself.
Training in Malta – Why It Works for Both Paths
Malta delivers perfect environments for both:
Trimix training
- 45–60 m wrecks from shore
- Clear drills on the Cirkewwa platforms
- Smooth transitions from Tec45 to Tec50
CCR training
- Controlled shallows for loop work
- Deep walls and wrecks for 60–100 m progression
- Stable conditions for multi-day courses
- Minimal currents, predictable weather
Few places in the world offer such clean progression.
Final Decision Guide – Quick Answers
Go Trimix First If…
- You want to improve OC skills
- You dive occasionally
- You prefer a lower upfront cost
- You want to take it slow and steady
Go CCR First If…
- You want 60–100 m wreck capability
- You want longer bottom times
- You’re tired of helium bills
- You want a long-term deep diving platform
Unsure? Start with Tec40/45.
You will know exactly which path feels right.
Is Technical Diving for Me? Your Path from AOW to Tec Diver in Malta
Introduction – The Step Beyond 30 Metres
If you’re reading this, you’ve probably felt the limits of recreational diving:
- You’ve hit 30–40 m and wanted more time.
- You want to explore deeper wrecks.
- You’re curious about twinsets, deco gases or even rebreathers.
- You’ve realised that “more depth” isn’t about adrenaline – it’s about more possibilities.
That’s where technical diving begins.
What Is Technical Diving? (Clear, No-Nonsense Definition)
Technical diving is simply planned diving beyond recreational limits, with:
- Mandatory decompression
- Multiple cylinders or a rebreather
- Redundant systems
- More detailed planning
- More responsibility
It’s not about being extreme or “pushing limits”. It’s about gaining the training and equipment to dive longer, deeper and safer on the sites you actually want to explore.
Signs You’re Ready for Technical Diving
Most people don’t wake up one morning ready for Tec. But these are the real signs:
1. You want more time on deeper sites
You’ve hit 30 m and thought: “This can’t be all there is.”
Wrecks like the Hellespont, Le Polynesien, HMS Stubborn and deeper reefs demand technical profiles.2. You enjoy the planning side of diving
Gas planning, decompression, equipment configuration – you enjoy thinking it through.
3. You value mastery and precision
You’re the diver who checks kit twice, stays in trim and wants to improve skills.
4. You like structured progression
Tec isn’t a quick fix. It’s a sequence: twinset → Tec40 → Tec45 → Tec50 → trimix → (maybe CCR).
If that excites you, you’re exactly the right candidate.Prerequisites: What You Need Before Starting Tec40
You don’t need to be elite.
You need:
- PADI Advanced Open Water (or equivalent)
- PADI Rescue Diver (or equivalent)
- 50 logged dives minimum
- Solid buoyancy, trim and situational awareness
If you’re not sure about your skill level, Jason can assess this on a single dive or tune-up session.
Tip: Many divers think they’re not good enough for Tec yet, when in reality they’re already close.
Your Pathway: From AOW to Tec Diver in Malta
Malta is uniquely suited for a clean, structured progression. You can do each step on local sites perfectly matched to the level.
Step 1 – Twinset / Intro to Tec
Learn:
- Twinset setup
- Shutdowns
- Trim & buoyancy
- Basic gas management
This is the foundation of everything.
Step 2 – PADI Tec40 (first real technical level)
Depth: 40 m
Gas: Single deco gas (up to 50%)
Skills:- Decompression stops
- Gas switches
- Longer dive planning
This is the level where it “clicks” – you become a technical diver.
Step 3 – PADI Tec45 (deeper & longer)
Depth: 45 m
Gas: One deco gas (up to 100% O₂)
Skills:- Longer decompression
- Failures & rescue on technical profiles
- More complex planning
- More bailout responsibility
By the end of Tec45, you’re a capable, self-sufficient technical diver.
PADI Tec45 and Tec50 programmes in MaltaStep 4 – Optional: Tec50 / Trimix / Prism 2 CCR
Depending on your goals:
- Stay on open circuit and go deeper with trimix
- OR go rebreather early (many do)
If you have long-term goals like 60–100 m wreck dives, CCR is the smart choice.
Hollis Prism 2 CCR training in Malta
Why Malta Is the Ideal Place to Become a Technical Diver
Malta is a unique training environment because it offers progression in one place:
1. Perfect depth ranges
- 5–20 m (skills training)
- 30–40 m (Tec40-level wrecks)
- 45–60 m (Tec45/Tec50 wrecks)
- 70–100+ m (trimix & CCR projects)
No flights, no big logistics jumps – you can grow step by step.
2. Controlled shore entries for training days
You can do shutdowns, gas switches and deco drills without worrying about boat cost or offshore conditions.
3. Real wrecks at real depths
No swimming over sand – actual historical wrecks with structure and purpose.
4. Predictable conditions
Much more reliable than the UK or northern Europe, especially for sequential training days.
5. One instructor through your whole journey
Instead of switching schools every course, you can build consistency, trust and realistic development with Jason.
What Technical Diving Is Not
Let’s address the myths:
- ❌ It is not about being reckless
- ❌ It is not about depth for bragging rights
- ❌ It is not for people who rush training
- ❌ It does not require you to be super fit or superhuman
Good technical divers are calm, conservative, and methodical.
If that sounds like you, you’ll do well.
What Technical Diving Is
- ✔ Safer and more controlled than recreational deep diving
- ✔ A path to real wreck exploration
- ✔ A skillset that lasts your whole diving life
- ✔ A progression you can take at your own pace
- ✔ A gateway to rebreathers, trimix and expedition-style diving
Costs and Time: A Realistic Overview
Costs vary by equipment and gas, but here’s the simple version:
- Twinset setup: €600–€1200 depending on what you buy
- Tec40: 3–4 days
- Tec45: 3–4 days
- Complete path (twinset → Tec45): 2–4 weeks depending on schedule
- CCR later: The Hollis Prism2 is the logical next step
Why Train With Jason in Malta?
If you choose a Tec instructor, you’re choosing:
- Their experience
- Their biases
- Their safety margins
- Their approach to problem-solving
- Their attitude toward discipline and bailout
Jason brings:
- 500+ hours on the Hollis Prism2
- PADI Tec CCR 100 achieved at 27
- Thousands of dives from UK quarries to 100 m+
- A methodical, calm teaching style
- Focused progression towards wreck diving
- Small groups only (1–2 students max)
You’re not buying a course.
You’re buying a pathway.Ready to Start Your Tec Journey in Malta?
Whether you’re:
- An AOW diver wondering if Tec is for you
- A Rescue diver ready for the next step
- A future CCR diver exploring options
- Or someone dreaming of deep wrecks
…your technical journey can start right here in Malta.
Open Circuit vs Closed Circuit Tech Diving | Hollis Prism 2
Open Circuit Technical vs Closed Circuit Technical – And Why I Teach on the Hollis Prism 2
Technical diving has never been more accessible. Deeper wrecks, longer bottom times, and safer gas planning are now part of many divers’ progression—from Advanced Open Water and Rescue, into Tec, and eventually into rebreathers.
But at some point, every aspiring tec diver hits the same question:
Should I stay on open-circuit technical, or move to closed-circuit (CCR)?
In this guide, I’ll break down the practical differences between open-circuit (OC) technical diving and closed-circuit (CCR) technical diving, and explain why I choose to teach on the Hollis Prism 2 here in Malta.
Quick definitions: what do we mean by OC and CCR?
Open-circuit (OC) is what most divers learn on first:
- You breathe gas from a cylinder.
- Exhaled gas goes straight into the water as bubbles.
- Gas mix is fixed (e.g. air, nitrox 32, trimix 21/35), so your gas and decompression plan is built around a fixed mix.
Closed-circuit rebreathers (CCR) recycle your breathing gas:
- You breathe into a loop; CO₂ is removed by a scrubber.
- Oxygen is added automatically or manually to maintain a set partial pressure of oxygen (PO₂).
- You exhale back into the loop—very few bubbles, very efficient gas use.
The Hollis Prism 2 is a back-mounted, fully-featured eCCR designed specifically for technical and expedition diving. It’s widely used for wreck, cave, and deep trimix diving because of its robustness, redundancy, and stable work-of-breathing at depth.
Why most divers start with open-circuit technical
Almost every technical diver begins on open circuit for good reasons:
1. Familiar kit, clear progression
If you already dive twinsets or sidemount, PADI Tec 40/45/50 and Tec Trimix build straight on that foundation. You’re:
- Using regulators, wings, and cylinders you more or less recognise.
- Learning solid gas planning, decompression theory, and problem solving without adding a complex machine on day one.
For many divers, this is the most sensible progression:
- Master buoyancy, trim, and situational awareness on recreational kit.
- Learn staged decompression and mixed gas on open circuit.
- Then decide if CCR is right for your long-term goals.
2. Simpler mental model when things go wrong
On open circuit, the options are very clear:
- Out of gas? Share gas and ascend.
- Free-flowing regulator? Shut down and switch.
- Lost gas? Switch to backup gas and adjust the plan.
The complexity is in planning and logistics, not in the life-support system itself. For a lot of divers, this makes OC a great environment to build confidence and discipline before they move to rebreathers.
Where open-circuit technical starts to hurt
Open circuit can absolutely take you deep and far—but it has trade-offs.
1. Gas cost and logistics
Deep trimix on open circuit is expensive and heavy work. For deeper dives you may be:
- Filling large volumes of helium-based trimix.
- Carrying two back-mounted cylinders plus multiple deco stages.
- Doing short bottom times because gas is the limiting factor, not your decompression tolerance.
On a place like Malta’s deeper wrecks, a single OC trimix dive can mean:
- High gas bills
- Multiple deco bottles
- Limited repetition during a week-long trip
2. Limited bottom time
Because your breathing rate is constant and gas is vented into the water, every minute at depth has a real cost in gas. Even with big twinsets and multiple stages, you’re often working within tight limits.
If your ideal dives involve:
- Long exploration passes on wrecks
- Multiple deep dives in a week
- Filming or photography where time and stability matter
…then open circuit starts to feel restrictive.
Why technical divers are moving to CCR
Closed circuit rebreathers like the Hollis Prism 2 were designed to solve exactly those problems.
1. Massive increase in gas efficiency
On CCR, you’re only adding oxygen to replace what your body metabolises. Helium and diluent are barely used. The result:
- Much lower gas consumption, especially on deep and long dives.
- Trimix dives that would be prohibitively expensive on OC become realistic.
- Less weight and fewer cylinders to carry to the site.
Over a season of deep diving, the gas savings alone can offset a lot of the cost of CCR training and equipment.
2. Stable PO₂, optimised decompression
Because the unit maintains a constant setpoint, you’re diving with an optimised PO₂ profile throughout the dive:
- More efficient decompression for the same exposure.
- Flexibility to adjust PO₂ for work rate, depth, and deco strategy.
- The ability to extend bottom time without a proportionate penalty.
On wrecks around Malta in the 50–80 m range, this often means:
- Longer time on the wreck at a safer PO₂.
- More flexibility to explore, shoot video, or run multiple passes.
3. Warmer, quieter, more immersive
Many divers underestimate how much this matters:
- Warm, moist breathing gas vs cold, dry open-circuit gas.
- Minimal bubbles, which is huge for photography, marine life, and wreck ambience.
- Less noise and mask flushing, more time focusing on the dive itself.
Once you get used to that experience on a Prism 2, open circuit often feels like a step backwards for certain types of dives.
Why the Hollis Prism 2 specifically?
There are several CCRs on the market. I teach on the Hollis Prism 2 because it’s:
Built for serious technical and wreck diving
The Prism 2 is designed as a full technical platform, not a recreational toy:
- Back-mounted counterlungs keep the chest clear for stages and scooters.
- Solid work-of-breathing performance in the depths and positions we use on wrecks.
- A configuration that integrates well with deco/stage bottles, DPVs, and long penetrations.
Proven, supported, and standardised
The Prism 2 has:
- A long track record in cave, wreck, and expedition environments.
- Good manufacturer support and a global user base.
- A clear training pathway from entry-level CCR to trimix and advanced levels.
For students, that means:
- You’re not on an obscure or orphaned unit.
- There’s a clear progression from first CCR dives to serious technical projects.
Excellent platform for Malta’s wreck diving
Malta offers high-visibility, easily accessible wrecks in the 40–100 m range. The Prism 2 fits that environment perfectly:
- Efficient gas use makes multiple deep wreck dives in a week affordable.
- Minimal bubbles respect the wreck environment and marine life.
- Configuration is ideal for wreck penetration techniques you’ll learn as you progress.
So should you stay on open circuit or move to CCR?
Here’s a simple way to think about it.
Open-circuit technical may be better if:
- You’re just starting out with technical concepts: gas planning, redundancy, decompression.
- You want to build experience step-by-step without adding a complex machine yet.
- Your typical dives are:
- 40–50 m range
- Limited decompression
- Shorter, high-focus training dives
In that case, a PADI Tec 40/45/50 or Tec Trimix course on open circuit is an excellent foundation before CCR.
Closed-circuit (Hollis Prism 2) becomes compelling if:
- You know you want to dive deeper, longer, and more often.
- You’re drawn to wreck exploration, filming, or project diving.
- Gas cost and logistics are starting to limit what you can realistically do.
- You’re ready to commit to regular practice, unit maintenance, and ongoing training.
Then a Hollis Prism 2 CCR course isn’t just a toy—it’s an investment in how you’ll dive for the next decade.
Training pathway: combining OC Tec and Hollis Prism 2
A smart progression for many divers looks like this:
- Solid recreational base
- Advanced Open Water (or equivalent)
- Rescue Diver
- 50–100 logged dives with good buoyancy and situational awareness.
- Open-circuit technical training
- PADI Tec 40/45/50 to learn:
- gas planning
- staged decompression
- emergency management
- Optional: Tec Trimix for helium-based deep diving.
- PADI Tec 40/45/50 to learn:
- Transition to CCR on the Hollis Prism 2
- Entry-level CCR course focusing on:
- unit setup and pre-dive checks
- loop management and buoyancy
- dealing with CCR-specific failures.
- Progress to deeper/trimix CCR levels as your experience grows.
- Entry-level CCR course focusing on:
This way, when you climb onto a Hollis Prism 2 in Malta, you’re not also trying to learn basic decompression and team skills from scratch—you can focus on mastering the unit.
Common myths about CCR (and the reality)
“CCR is only for extreme depths.”
Not true. Many divers use the Hollis Prism 2 for 40–60 m wrecks specifically because:
- It reduces gas costs.
- It keeps them warmer and more comfortable.
- It allows longer, more relaxed bottom times.
“Rebreathers are too dangerous.”
Any life-support system is dangerous if used poorly. CCR demands:
- Strict pre-dive checklists.
- Regular maintenance.
- A commitment to ongoing training and practice.
With proper instruction, solid procedures, and conservative planning, CCR can be at least as controlled as open-circuit technical diving—often with more redundant information (multiple PO₂ displays, integrated computers, bailout options).
“I’ll lose my OC skills.”
A good training programme keeps you current on both:
- You’ll still plan bailout and deco as if you might need to go OC at any time.
- Many CCR divers retain a twinset for skills, backup, or specific dives.
On my Hollis Prism 2 courses in Malta, we emphasise maintaining core technical skills alongside CCR-specific procedures.
Why train Hollis Prism 2 CCR in Malta?
Malta is one of the best classrooms for both open-circuit technical and Hollis Prism 2 CCR:
- World-class wrecks in the 30–100 m range.
- Typically clear, warm(ish), blue water with easy boat access.
- A mix of:
- training-friendly sites
- deeper, more advanced wrecks for later in your progression.
For CCR specifically:
- You can get multiple quality dives in a week without burning through obscene amounts of trimix.
- Conditions are consistent enough to focus on your skills and the unit, not just surviving the environment.
Bringing it together: choosing your next step
Open-circuit technical and closed-circuit technical are not rivals—they’re stages in the same journey.
- Open circuit technical gives you the foundation:
gas planning, redundancy, decompression discipline, team skills. - Closed circuit on the Hollis Prism 2 gives you the range:
longer times, deeper wrecks, and more ambitious projects—especially here in Malta.
If your long-term goals involve:
- Regular trips to deep wrecks.
- Serious time underwater on each dive.
- Project-style diving, filming, or exploration.
…then the Hollis Prism 2 is very likely your next logical step.
Ready to talk about your path?
Whether you’re:
- An experienced OC tec diver wondering if CCR is worth it, or
- A motivated recreational diver looking at the full pathway…
I can help you map out a training plan that fits your experience, budget, and goals—from PADI Tec courses on open circuit through to Hollis Prism 2 CCR training and guided wreck dives in Malta.
Get in touch to discuss:
- Which course or level makes sense for you.
- How to plan a Malta tec week around your training.
- Options for guided Hollis Prism 2 CCR wreck dives once you’re certified.