Overview

 

Our world class rebreather training in North Carolina will give you all of the skills, knowledge, and experience you need to safely plan and execute complex rebreather dives to sought after dive sites around the world. Diving on a rebreather is an advanced method of SCUBA that utilizes a closed or semi closed system to capture and reuse spent gas. This allows divers to enjoy longer bottom time, and reduce the amount of gas that they consume while diving. While this wonderful bottom time machine comes with benefits that will blow your mind, it also comes with a few challenges for potential rebreather divers to consider.

 

Principles of Rebreather Diving

 

1.) Basic Operation

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• Closed Circuit: Closed circuit rebreathers (CCR) retain exhaled gas and push it through a filtering process to remove carbon dioxide (CO2). As the diver is metabolizing oxygen the machine replaces it by adding small doses of pure oxygen to the mix. Depending on the model, oxygen addition can be done either electronically and controlled by the computer while monitored by the diver, or manually by the diver.

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• Semi Closed Circuit: Semi-closed circuit rebreathers (SCR) use a pre-mixed, oxygen rich gas is added to the breathing loop constantly at a rate that corresponds with the divers breathing rate. With every breath cycle the diver is metabolizing some of the oxygen, and at a predetermined limit of oxygen content the machine will vent the gas while replacing it all the time with fresh breathing gas.​

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2.) Gas Composition:

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• Rebreathers work by blending pure oxygen, and a diluent gas. The diluent is typically air, but can be substituted for different blends depending on the needs of the diver and the demands of the particular dive being undertaken. 

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• The diver is in control of the partial pressure of oxygen in the gas that they breathe during a dive. When diving on a manual rebreather, the diver is the only system responsible for observing and maintaining the partial pressure of oxygen, but even when using an electronic rebreather, they are responsible for monitoring the partial pressure and maintaining it in case of equipment failure.

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3.) Benefits of recycling exhaled gas:

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• Reduced gas consumption is achieved through gas recycling by capturing and reusing oxygen left in exhaled gas. This leads to the diver needing to enjoy much longer dive times, while carrying a much smaller supply of breathing gas.

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• The absence of gas being exhausted reduces the noise to silence, which leads to a much more serene diving experience, and allows the diver to become one with the environment that they are exploring. Divers report much more intimate observations with marine life as they are no longer spooking them with the abrupt noise caused by exhausting spent gas into the water.

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• Divers also experience much shorter decompression times by controlling the partial pressure of oxygen throughout the entire dive. While open circuit tech divers must account for changing partial pressures of oxygen and nitrogen ​throughout the dive and increase their decompression time based on that change, closed circuit divers control and monitor gas blends in real time. The advantage is that the closed circuit diver can maintain high oxygen blends, or more accurately lower nitrogen blends throughout the entire dive which reduces the nitrogen absorption that leads to DCS.  

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• Open circuit divers often experience extreme fatigue after a diving day, which leads to those long boat naps and gear washing dread that we have all come to expect as divers. However CCR divers report feeling much more alert and less groggy after diving on a rebreather. This is due to the lower nitrogen absorption in the body caused by monitoring and maintaining a higher setpoint of oxygen throughout the dive.

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Benefits of Rebreather Diving

 

1. Extended Dive Time:

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• Rebreathers make it possible for divers to stay underwater much longer compared to open circuit diving.

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    2.) Decreased Gas Expense: 

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• Divers can carry and use much less gas on a dive by reusing oxygen and minimizing nitrogen use.

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• With gas prices increasing, especially more advanced oxygen rich blends and helium blends, this is a much more appealing option for divers who want to dive very frequently.

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1. Reduced Impact to Environment: 

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• CCR divers are not releasing bubbles into the water, which leads to a much more quiet experience that is not only enjoyed by the diver, but also the marine life. 

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• More and more explorers, scientists, and underwater wildlife enthusiasts are turning to CCR for its ability to bring divers in close proximity to wildlife and to see the them in a more natural and undisturbed state.

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   3.) Increased Flexibility: 

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• Divers can explore a wider range of environments, especially deeper and more complex dives.

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• By using a rebreather along with the standard open circuit bailout system, divers are afforded many options during emergencies, and can often fix a problem and return to the loop.

 

   4.) Enhanced Safety:

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• With proper training, rebreathers can lower the risk of decompression sickness due to much slower ascent rates and real time gas blending, that gives the perfect mix for the human body at every depth.

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Risks and Challenges:

 

1.) Technical Complexity:

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• Rebreathers demand more training and a thorough understanding of their mechanics and gas management. Training is much more in depth, and demanding, and at the same time much more rewarding

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• Proper operation and maintenance is a must to avoid malfunctions on the machine. Divers must learn the ins and outs of the rebreather so that they can maintain and service them properly.

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2.) Oxygen Toxicity:

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• If not monitored correctly, oxygen levels can spike and lead to seizures and other dangerous conditions. 

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3.) Carbon Dioxide:

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• Improper scrubber packing or diving longer than the rated time allotment on the scrubber can lead to a buildup of carbon dioxide in the loop leading to a condition known as hypercapnia. 

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• Hypercapnia can affect cognitive function, physical performance, and ultimately lead to passing out underwater leading to death. 

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4.) Dive Planning:

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• More complex dive planning is required of rebreather divers to ensure safety, especially when taking on greater depths, requiring complex gas mixes.

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• Redundancy of gear, staying up to date on best practices, and maintaining proficiency all play a part in dive planning alongside gas planning to make sure that the diver has not only enough gas in the CCR, but also a sufficient bailout to come off of the CCR at any point in the dive if a malfunction should occur.

 

Equipment Overview

 

1.) Rebreather Unit:

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• The CCR is made up of a scrubber, oxygen supply, diluent supply, electronic or manual controllers for gas, breathing loop, counterlungs, BCD, backplate, and a harness

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2.) Scrubber Material:

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• Composed of calcium hydroxide, which binds to co2 in exhaled gas to keep it from returning to the diver.

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• Different brands, and granule sizes are available for purchase and should be determined by the rebreather manufacturer and stated in the manual.

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3.) Oxygen Supply: 

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• High pressure tanks of different sizes are available for the unit at the manufacturers direction. 

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• Should be oxygen cleaned and certified to be filled with pure oxygen by a qualified person.

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4.) Dive Computer: 

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• Mandatory for rebreather divers to control partial pressure of oxygen, ascent rates, and bottom times.

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5.) Additional Gear:

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• Standard dive equipment including wetsuits, drysuits, fins, mask, dive knife, surface marker buoy, signaling devices.

 

Training and Certification

 

1.) Courses Available

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• Our entry level CCR course, tech 40, focusses on equipment familiarity, gas management, emergency procedures, and dive planning.

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• The course is both very demanding and rewarding, as students learn to be a master of a very complex machine and operate it with precision to become a technical diver.

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• Student to instructor ratio is kept very small to ensure a thorough learning process for the prospective CCR diver.

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2.) Experience Requirements

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• Certified advanced open water diver

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• Enriched air diver

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• Certified deep diver or show proof of 10 dives to 100 feet 

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• Have a minimum of 30 dives with at least ten of them using enriched air deeper than 60 feet

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• Be at least 18 years old

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• Be a certified rescue diver before training dive 5

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• Have 50 logged dives before certification

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3.) Practical Skills:

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• Emphasis on safety procedures, dealing with emergencies, and managing gas levels.

 

Conclusion

 

Rebreather diving is the gateway to exploration of longer, quieter, and more immersive underwater experiences. While giving divers amazing benefits, it also requires an in-depth understanding of equipment, and procedures. With proper training and application of the technology, rebreather diving can enhance the underwater experience significantly.

 

Further Exploration

 

If you are interested in pursuing a rebreather diving certification in North Carolina, rebreather dive site recommendations, or personal experiences, feel free to reach out via phone or email. We look forward to undertaking this life changing endeavor with you soon!

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Phone: 252-665-1841

email: encounterscuba@gmail.com

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