TDI CCR Advanced Mixed Gas Diver Course Overview

The highest level of Closed Circuit Rebreather (CCR) training that TDI offers, the Advanced Mixed Gas Course will teach you how to use the full capabilities of a CCR. With a maximum depth of 100 metres/330 feet, this course opens up a whole new realm of diving including new wrecks, caves and walls to explore in depths you previously could not reach on a rebreather. This intensive course conducted over seven dives will focus on all the elements needed to plan and execute dives to these depths.

Who this course is for?

The certified TDI Mixed Gas CCR Diver (or equivalent) looking to extend their depth limitations

Course prerequisites:

Minimum age 18
Certified TDI CCR Mixed Gas Diluent diver, or equivalent from agencies recognized by TDI
Have verified logs of a minimum of 100 hours as a certified CCR diver over a minimum of 100 dives; a minimum of 50 hours and 50 dives must be on the unit specific CCR. Fifty percent of these dives must be deeper than 30 metres/100 feet. All dives to be deeper than 9 metres/20 feet

What you can expect to learn:

The TDI Diving Rebreathers Student Manual is required for use as a review/recap document. The instructor may use any additional text or materials they feel will represent the topic in an educational manner. The following topics must be covered during the course:

Gas physiology
- Oxygen (O2) toxicity
- Hypoxia
- Nitrogen absorption
- Helium absorption
- HPNS
- Carbon dioxide (CO2) toxicity
- Gas consumption
- Gas mixing
Formula Work
- Oxygen (O2) metabolizing calculations
- Manually controlled closed circuit rebreathers
- Equivalent narcosis depth theory
- Central nervous system (CNS) tracking
- Oxygen tracking units (out)
- Gas management
Dive tables
- Creation of custom dive tables appropriate to dive depths
- Creation of lower percentage oxygen (PO2) diluent to support loop flushing and bailout at depth
Dive computers
- Mix adjustable
- Constant partial pressure of oxygen (PPO2)
- Oxygen (O2) integrated
Dive Planning
- Operational planning
Equipment Maintenance
- Fuel cell management
- Loop configurations
- Additional fitted equipment and modifications

Required skill performance and graduation requirements:

The following open water skills must be completed by the student during open water dives with the following course limits:

No dives deeper than 100 metres/330 feet
No dives shallower than 40 metres/130 feet other than the 1 air diluent configuration dive
Equivalent narcosis depth not to exceed 30 metres/100 feet
Calculate all off-board gas at litres 45.30/1.06 cubic feet per minute usage to cover stress situations
PO2 not to exceed manufacturer recommendation or a working limit of 1.3 bar during the bottom phase of the dive and 1.4 bar during the decompression phase of the dive
Diluent PO2 should not exceed 1.2 at maximum depth
All dives to be completed within appropriate fixed PO2 decompression tables or decompression planning software
All dives to be completed within CNS percentage limits with a recommend maximum of 80 percent of the total PO2 CNS limit
The student is only certified for CCR mixed gas diving on the rebreather being used

Land drills:

Build unit based on manufacturer’s specifications using manufacturer’s manual/build checklist
Demonstrate familiarity with basic and intermediate hand signals
Select and prepare equipment suitable for soft overhead environment with long decompression obligations
Conduct team oriented drills for lift bag deployment and gas switching procedure
Drills for buddy rescue
Properly analyze all gas mixtures to be used
Demonstrate adequate pre-dive planning
- Limits based on system performance
- Limits based on bailout gas requirements
- Limits based on oxygen exposures at chosen PPO2 levels
- Limits based on manually controlled closed circuit rebreathers
- Limits based on nitrogen absorption at planned depth and PPO2 (setpoint) level
- Limits based on helium absorption
- Correct narcotic depth planning and diluent selection to allow cell flushing at target depth (diluent should not exceed a PO2 of 1.2 at maximum planned depth)

Pre-dive drills:

Conduct pre-dive checks using TDI Pre-flight checklist
Use START* before every dive
Stress analysis and mitigation

Some in-water skills:

Show good awareness of buddy and other team members through communications, proximity and team oriented dive practices
Demonstrate buoyancy control; ability to hover at fixed position in water column without moving hands or feet
Properly execute a recovery from a system failure and conclude the dive and decompression on open circuit gases carried
Properly execute a recovery from a system failure and conclude the dive and decompression with the unit in manual mode
Gas shutdowns and loss of gas, correct choice and switching to off board gases
Broken hoses, disaster scenarios
Flooded absorbent canister
Cell errors
SCR drill (minimum of 10 minutes)
Oxygen rebreather mode in depths less than 6 metres / 20 feet
Manually control CCR Unit for one full dive including all decompression stops
Demonstrate competence managing 3 bailout cylinders, including drop and recovery while maintaining position in the water column
Demonstrate proper understanding and implementation of team bailout procedures and conduct a team bailout from a depth greater than 40 metres/130ft
Demonstrate ability as a team to plug in and share off-board gas, including team sharing/swapping of off-board bailouts
On 2 of the dives, demonstrate an ascent with ascent reel and lift bag and perform staged decompression
Proper execution of the dive within all pre-determined dive limits
Ability to manage multiple failures in adverse conditions
Demonstrate of surface support/support divers in dealing with bailout scenarios

What’s in it for you?

Upon successful completion of this course, graduates may engage in technical diving activities utilizing the unit specific CCR to a maximum depth of 100 metres/330 feet utilizing any mixed gas diluent appropriate to the dive plan provided:

The diving activities approximate those of training
The areas of activities approximate those of training
Environmental conditions approximate those of training