Rebreather Courses

Rebreathers require special training to be used underwater. Training is the first step in learning the crucial procedures that make rebreather diving enjoyable and mitigate risk to an acceptable level. Most rebreather manufacturers won’t even sell a unit without the diver being committed to a training course. Even then they will send the unit to the instructor to ensure no diving happens outside the course. This applies to people totally new to diving rebreathers and people who are extremely experienced diving rebreathers.

Depending on your experience as a scuba diver, there are different paths you can take to begin your rebreather journey. If you’re already a certified decompression diver you can jump right into decompression dives on the unit. If not, you’re able to get a no-deco certification to build experience as a rebreather diver before dipping your toes into the decompression world.

Agencies have specific terminology for their courses and that can be confusing. Divers often refer to the courses as MOD 1, MOD 2, and MOD 3. These are generic terms referring to the order of training on a CCR. MODule 1 is an introductory CCR course, MODule 2 is a trimix course using normoxic trimix, and MODule 3 is hypoxic trimix. These generic terms help keep everyone on a similar footing so they don’t get lost in the nomenclature of “advanced mixed gas” vs. “full trimix” vs. “hypoxic trimix”. There are a few options for MOD 1 – explained in more detail below.

These descriptions are general and not inclusive of all aspects of training. Please reference course standards for complete information on CCR courses.

This is where it all starts. MOD 1 is the intro certification for rebreather divers. Your path here depends on your current experience as a technical diver. Taken as your first course these courses are ~7 days long.

Air Diluent – You can use air as diluent and do dives to a maximum of 100ft.

Air Diluent Deco – You can use air as diluent and do decompression dives to a maximum of 130ft.

Helitrox Diluent Deco – You can use trimix as diluent and do decompression dives to a maximum of 150ft.

If you have sufficient technical diving experience the helitrox course is my suggestion. This gives you the ability to use trimix as diluent which is preferred in CCR diving past 100ft. Trimix gives you clarity at depth and improves the function of the rebreather. It lowers work of breathing (WOB),  reduces inert gas narcosis and improves scrubber function. Even if you only plan to dive between 100-130ft I suggest the helitrox class for experienced technical divers. Both helitrox and air dil deco require about the same equipment. Bailout cylinders with a gas that’s breathable at depth, one decompression cylinder, and a backup dive computer in CCR mode are essential items for these courses.

If you aren’t a technical diver then your MOD 1 will be Air Dil and after you build sufficient time and experience on the unit you’ll be able to upgrade to deco or helitrox deco with an abbreviated class.

MOD 2 is much less complex than MOD 1. There is only one iteration for MOD 2 programs and that’s noromoxic trimix. Normoxic means that there’s enough oxygen in the diluent to sustain life at the surface. Common normoxic mixes are 18% oxygen and 45% helium or 21% oxygen and 35% helium. Normoxic dives on a CCR are conducted between 150ft and 200ft deep. This course is a decompression course and can require 1-2 deco cylinders as bailout. You must have completed one of the MOD deco courses before enrolling in MOD 2.

The third and final core CCR course is hypoxic trimix. This course goes to a max depth of 330ft and will require 3+ bailout cylinders. Hypoxic divers use percentages of oxygen that cannot sustain life at the surface – less than 18% oxygen. Hypoxic trimix divers need to have significant experience CCR diving before doing dives at this level.

If you’re already certified to dive a rebreather and you get a different model you have to take a class on that specific model to be qualified to dive it. That may seem unnecessary to some, but from a liability and risk standpoint, it’s necessary. Unit-specific training is required by all major agencies and manufacturers. For all the core CCR courses there’s an abbreviated “crossover” course to get qualified to dive your new unit in a short amount of time, typically 3 days. This gives you experience assembling and diving the unit while still respecting your general CCR knowledge and skills.

The Cave CCR program came about to fill in CCR-specific techniques, planning, and configurations in the cave environment. There is an 8-day program for those new to cave diving and an abbreviated 3-day course for people who hold cave certifications already. The 8-day program follows a similar path that open circuit cave divers take and is typically split into two programs with dives for experience in between. The abbreviated program is often called a “crossover” and is designed for people who are CCR certified with experience and are open circuit full cave certified. Since these people are already cave divers they typically need less time to get up to speed on CCR cave diving.

Check out the links below for more information on training and purchasing a unit.