Exploring the Horizon

The Mares Horizon Semi-Closed Rebreather

In the realm of underwater exploration, technology has continuously pushed the boundaries of what is possible. One such innovation that has revolutionized diving is the semi-closed rebreather. Among the myriad of rebreathers available in the market, the Mares Horizon Semi-Closed Rebreather stands out as a pioneering solution. This rebreather is a game-changer, offering divers a unique and efficient way to explore the depths while minimizing gas consumption and maximizing safety.

In this comprehensive blog post, we will delve deep into the world of semi-closed rebreathers, with a particular focus on the Mares Horizon SCR. We will explore its working principles, advantages, drawbacks, and how it is transforming the world of diving. So, fasten your seatbelts, or rather, your dive belts, and let's embark on an underwater journey with the Mares Horizon Semi-Closed Rebreather.

Understanding Rebreathers
Before we dive into the specifics of the Mares Horizon Semi-Closed Rebreather, it is essential to grasp the fundamentals of rebreathers. Rebreathers are a specialized type of scuba equipment that recycle a diver's exhaled breath, removing carbon dioxide and replacing the consumed oxygen. This creates a closed-loop system, unlike open-circuit scuba diving, where exhaled gas is released into the water.

When it comes to SCUBA diving, there are three primary categories: open-circuit, closed-circuit, and semi-closed circuit. The open-circuit system is the most commonly used by recreational divers. However in recent years, semi-closed rebreathers have been gaining popularity due to their significant advantages.

Semi-Closed Rebreathers - The Middle Ground
Semi-closed rebreathers bridge the gap between open and closed-circuit systems. These systems release a portion of the exhaled gas into the water while recycling the majority. One of the key advantages is their extended dive time due to the efficient use of gas.

With a semi-closed rebreather and their efficient use of breathing gas, divers can explore for longer without the need for extensive decompression stops and multiple cylinder configurations (travel gas, bottom gas, deco gas etc). This makes them an excellent choice for recreational divers, technical divers, scientific divers and any other deep-sea explorer.

The Birth of the Mares Horizon SCR
Mares is a reputable name in the world of diving equipment, known for its innovation and commitment to safety. The Mares Horizon Semi-Closed Rebreather was developed utilising REVO technology and with a focus on creating an efficient and reliable system for divers, whether they are seasoned veterans or just starting their underwater journey. It was specifically designed to be a cost effective rebreather solution for the recreational market and has been well received by the global diving community.

The design of the Mares Horizon Semi-Closed Rebreather incorporates cutting-edge technology and materials. It is intended to be user-friendly, simple to set up, ensuring that both experienced divers and novices can use it with ease.

How Does the Mares Horizon Work?
At the core of the Mares Horizon Semi-Closed Rebreather is a complex set of mechanisms designed to optimize gas usage and maintain a safe breathing environment for divers. Here's how it works:

  1. Breathing Loop: The rebreather features a breathing loop that recirculates a diver's exhaled breath. This loop is equipped with sensors to monitor gas levels and adjust them as needed.

  2. Gas Mixing Unit: The rebreather includes a gas mixing unit that adds a precise amount of oxygen to the breathing loop to maintain the desired partial pressure of oxygen (PPO2). This ensures that the diver always has the right mix of gas to breathe.

  3. Overpressure Valve: Safety is a paramount concern in diving, and the Mares Horizon incorporates an overpressure valve to prevent excessive gas buildup in the breathing loop. This mechanism automatically releases gas if the pressure becomes too high.

  4. Exhalation Valve: To avoid excessive carbon dioxide buildup, the rebreather employs two scrubbing cartridges and features an exhalation valve that vents a portion of each exhaled breath into the surrounding water. This CO2-rich gas is then replaced with fresh oxygen from the gas mixing unit.

  5. Dive Computer: A dive computer, an essential part of the system, continuously monitors the diver's depth, time, and gas levels, providing real-time information on decompression status and safety limits.

Advantages of the Mares Horizon
The Mares Horizon Semi-Closed Rebreather offers numerous advantages, making it a top choice for divers. Some of these benefits include:

  1. Extended Dive Times: Semi-closed rebreathers significantly extend dive times compared to open-circuit scuba gear, making them ideal for deep-sea exploration, scientific work and technical diving.

  2. Reduced Gas Consumption: The efficient gas recycling system of the Mares Horizon means divers carry smaller tanks, reducing the physical strain and logistical challenges of diving.

  3. Perfect trim: Once the learning curve of understanding the units buoyancy characteristics have been completed, the diver can enjoy perfect trim as the unit puts the diver into this optimum position.

  4. Reduced dehydration: The breathing gas is warm thus reducing the cooling effect on the bodies core temperature compared to the cold breathing gas of traditional scuba. The gas is also moist which greatly reduces dehydration.

  5. Easy breathing: There is zero effort on the inhale compared to the traditional inhalation effort of normal open circuit regulators.

  6. Improved Decompression: With precise control over gas mixtures, the Mares Horizon minimizes the risk of decompression sickness, allowing divers to enjoy safer and more enjoyable underwater experiences.

  7. Stealthy Approach: The reduced bubble production when compared to open-circuit scuba diving makes it an excellent choice for underwater photographers and researchers, as it doesn't disturb marine life.

  8. Environmentally Friendly: Releasing fewer bubbles into the water is not only advantageous for stealth but also benefits the marine ecosystem by minimizing disturbances.

  9. Easy post dive care: Cleaning and sterilising the Horizon after diving is a quick and simple affair.

Drawbacks of the Mares Horizon
While the Mares Horizon Semi-Closed Rebreather offers numerous advantages, it is important to be aware of its drawbacks as well:

  1. Complexity: Learning to use a semi-closed rebreather can be more challenging than open-circuit scuba gear. Proper training is essential for safe operation.

  2. Maintenance: The rebreather requires semi-regular maintenance to ensure all components are functioning correctly. This adds an ongoing cost and effort to its use.

  3. Cost: High-quality semi-closed rebreathers, such as the Mares Horizon, can be expensive. The initial investment is a significant consideration for divers.

  4. Weight and Buoyancy: The added weight of the rebreather and cylinders along with the effect of the units counter lungs can affect buoyancy control, which may take time to master.

Training and Safety
Given the complexities and potential risks associated with semi-closed rebreathers, proper training is crucial. Divers must undergo specific training and certification to operate the Mares Horizon safely. This training covers equipment usage, maintenance, emergency procedures, and dive planning.

Safety is a paramount concern when using any rebreather. Divers must be vigilant in monitoring the system, following safety protocols, and having redundancy in place, such as carrying a backup open-circuit system in case of rebreather failure.

There are currently two training options for interested divers:

  1. The SSI SCR diver program provides divers with the training necessary to independently plan and conduct dives to a maximum depth of 30 meters, using Enriched Air Nitrox, not requiring decompression stops.

  2. The SSI SCR Extended Range program provides divers with the training necessary to independently plan and conduct limited decompression dives, using Enriched Air Nitrox to a maximum depth of 40 meters and specialised diving equipment and procedures, for a maximum accumulated accelerated decompression time of 25 minutes

Real-World Applications
The Mares Horizon Semi-Closed Rebreather is not limited to recreational diving. It has found applications in various fields including:

  1. Scientific Research: Marine biologists and researchers use semi-closed rebreathers to study underwater ecosystems without disturbing the environment.

  2. Commercial Diving: Professional divers who perform tasks like underwater welding and construction benefit from extended dive times and reduced gas consumption.

  3. Technical Diving: The rebreather's precision control of gas mixtures is invaluable for deep technical dives, including cave and wreck exploration.

  4. Military and Law Enforcement: Tactical divers employ semi-closed rebreathers for covert underwater missions, where minimising bubbles and maximising dive times are crucial. It is also a great choice for police divers where extended bottom times can assist with operations.

The Future of Semi-Closed Rebreathers
The Mares Horizon Semi-Closed Rebreather is just one example of the innovation happening in the world of diving technology. As technology continues to advance, we can expect further improvements in rebreather design, making them even more user-friendly, efficient, and safe.

Moreover, the growing popularity of semi-closed rebreathers might lead to more affordable and accessible options for divers of all levels. As the underwater world beckons, semi-closed rebreathers like the Mares Horizon will play an increasingly significant role in our exploration of the deep.

Conclusion: Diving into the Future
In the ever-evolving world of diving, the Mares Horizon Semi-Closed Rebreather is a beacon of innovation. Its unique blend of extended dive times, reduced gas consumption, and precise gas control has made it a game-changer for divers of all levels. However, its complexities and costs make it essential for divers to undergo proper training and ensure safety.

As technology continues to advance, we can anticipate further refinements in semi-closed rebreather design. These innovations will undoubtedly open new doors for divers, allowing them to explore the depths of our planet's oceans like never before. So, whether you're a seasoned diver or someone considering taking the plunge into the world of underwater exploration, the Mares Horizon Semi-Closed Rebreather offers an exciting and promising future for the world of diving.

Aotearoa Dive became New Zealand's very first official Mares Horizon training center in 2022 and offers retail of new units, servicing,  as well as Mares Horizon training programs.

For more information and pricing of the Mares Horizon CLICK HERE
For more information regarding training options CLICK HERE


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