TDI · Poseidon rebreather
TDI Helitrox CCR: Poseidon Se7en (45 m)
Helium in the loop: a clearer head, less gas density, and decompression diving to 45 m.
Air diluent is fine to 40 m, but narcosis and gas density build quickly past 30 m. Helitrox replaces some of the nitrogen in your diluent and bailout with helium. At the same depth your head is clearer and the gas is easier to breathe, which means better decisions and more margin when you need it.
This is the Poseidon's 45 m mixed-gas course, and the most advanced rebreather course I teach. It opens up the deeper wrecks and reefs off Perth on a gas that's right for the depth.
- Minimum age
- 18
- Two ways in
- Upgrade from Air Diluent CCR, or come straight from open circuit
- Duration
- At least 5 days (fewer for upgrades)
- In-water time
- 420 min over 7 or more dives; 240 min for upgrades
- Maximum depth
- 45 m
- Gases
- Diluent and bailout up to 35% helium, at least 20% oxygen; up to 100% oxygen for decompression
Prerequisites
- Minimum age 18.
- Either: TDI Air Diluent CCR Diver (or equivalent), with at least 30 hours over 30 dives on the unit and 6 months of CCR diving.
- Or, straight from open circuit: TDI Advanced Nitrox, Decompression Procedures or Helitrox (or equivalent), 50 logged dives, and at least 5 logged staged decompression dives to 30 m or deeper.
What you'll learn
- Helium: why it's used, what it changes, and what it costs
- Choosing and analysing a Helitrox diluent and bailout gas
- Planning mixed-gas CCR decompression, and its bailout
- Managing gas density, narcosis and oxygen exposure at depth
- Bailing out on Helitrox from depth, with a full decompression schedule
- Training dives carry up to 10 minutes of decompression, with at most two decompression dives a day
What you'll need
- Your Poseidon Se7en or MkVI Discovery, configured for Helitrox diluent. Hire is available, but owning your own is strongly recommended
- Bailout cylinder(s) with Helitrox or a suitable bailout mix, and regulators
- Ascent reel and SMB, cutting tool, exposure protection for long stops
- A helium analyser, or access to one. Ask me
Already a Poseidon Air Diluent diver?
Once you have 30 hours over 30 dives on your unit and 6 months of CCR experience, you can upgrade. That's a skills evaluation dive plus at least 4 open water dives, 2 of them deeper than 35 m, for 240 minutes in the water in total.
Why learn it with me
Helitrox is where I'm happiest teaching. It's the course that turns a capable rebreather diver into one who can plan and run a real 45 m decompression dive.
Course limits and prerequisites follow TDI Standards & Procedures, Part 2 (v0126), section 32. Standards change, so I'll confirm them when you book.
Interested?
Tell me your certifications and roughly how many dives you've logged, and I'll confirm you're ready.