Essgee Aqualung MK11 Siebe Gorman #1299
The Siebe Gorman Essgee Aqualung Mk II: A Pioneering Regulator in Diving History
The Siebe Gorman Essgee Aqualung Mk II is a legendary piece of diving equipment that highlights the ingenuity of mid-20th-century engineering. Produced in 1956 by Siebe Gorman & Co. Ltd., a British company with roots dating back to the early 19th century, the Mk II marked a significant step forward in the evolution of scuba diving technology. Building upon the success of its predecessor, the Essgee Aqualung Mk I, the Mk II incorporated innovative design elements that improved performance and usability. Consequently, it earned a place among the most notable regulators of its era.
Historical Background: Siebe Gorman’s Legacy
Siebe Gorman & Co. Ltd. has a storied history in the development of diving equipment. Augustus Siebe founded the company in 1819 and revolutionized underwater exploration with the invention of the closed diving helmet. This device allowed divers to work safely underwater for extended periods. By the mid-20th century, the company had expanded into scuba equipment. They leveraged a licensing agreement with the French company La Spirotechnique, which allowed Siebe Gorman to manufacture regulators based on the iconic CG45. Designed by Jacques-Yves Cousteau and Émile Gagnan, the CG45 was the world’s first commercially successful scuba regulator.
The Evolution from Mk I to Mk II
The Essgee Aqualung Mk I, introduced in 1955, was essentially a reproduction of the CG45. Siebe Gorman adapted it to imperial measurements and made minor design changes. While functional and reliable, it did not introduce groundbreaking innovations. Recognizing the need for a more advanced regulator, Siebe Gorman quickly developed the Mk II, which debuted just a year later in 1956.
The Mk II introduced significant improvements over the Mk I. It addressed several limitations and incorporated features that enhanced its performance. These changes aimed to reduce breathing resistance, improve mechanical efficiency, and make the regulator more user-friendly for divers.
Key Features of the Essgee Aqualung Mk II
- Dual Lever Mechanism: The Mk II’s addition of a second lever to the second-stage mechanism was among its most notable innovations. This design increased the mechanical advantage, making the regulator more sensitive to the diver’s breathing efforts. As a result, it significantly reduced breathing resistance, allowing for a smoother and more natural breathing experience underwater.
- Revised Yoke Block Positioning: In the Mk I, the yoke block was centrally positioned on the regulator body. For the Mk II, it was moved to the side. This change, necessitated by the new lever system, also reversed the orientation of the breathing flow in the hoses. Consequently, the exhaust horn, originally located on the right side in the Mk I, was moved to the left side in the Mk II. This adjustment improved the regulator’s overall ergonomics and performance.
- Distinctive Branding: The Mk II featured a large oval nameplate prominently displaying the inscription: “ESSGEE AQUALUNG MKII – SIEBE, GORMAN & Co. LTD – CHESSINGTON, SURREY.” The term “Essgee” was a phonetic representation of the initials “S” and “G” from Siebe Gorman. This branding gave the regulator a unique identity that distinguished it from its competitors.
- High-Pressure Port for Gauges: A forward-thinking feature of the Essgee Aqualung Mk II was the inclusion of a high-pressure port. This feature allowed divers to connect a pressure gauge, which was relatively rare at the time. It demonstrated Siebe Gorman’s commitment to enhancing safety and functionality.
Design and Construction
The Mk II was constructed using durable materials, ensuring reliability even in challenging underwater conditions. The regulator’s twin-hose design was characteristic of the era, with one hose for inhalation and the other for exhalation. This configuration minimized bubbles near the diver’s face, a critical consideration for activities such as underwater photography and military operations.
The regulator’s components were meticulously crafted, reflecting Siebe Gorman’s commitment to quality. Adding the second lever in the second stage was a particularly impressive engineering achievement, as it required precise calibration to function effectively without compromising reliability.
Performance and Reception
The Essgee Aqualung Mk II received widespread praise from the diving community for its improved breathing performance and innovative features. Divers appreciated the regulator’s sensitivity and ease of use, which made it suitable for both recreational and professional applications. Additionally, the inclusion of a high-pressure port was especially praised, as it allowed divers to monitor their air supply more effectively.
While the Mk II was a significant improvement over the Mk I, single-stage regulators such as the Mistral eventually overshadowed it. These offered simpler designs and similar performance. Nevertheless, the Mk II remains a historically significant regulator that showcased the potential of two-stage systems.
Collectibility and Legacy
Today, the Siebe Gorman Essgee Aqualung Mk II is a rare and sought-after collector’s item among vintage scuba enthusiasts. Its historical significance, innovative design, and connection to the pioneering era of scuba diving make it a prized addition to any collection. Collectors value the Mk II not only for its technical achievements but also for its role in advancing underwater exploration.
Restoring and preserving a Mk II requires careful attention to detail because replacement parts can be difficult to find. Many enthusiasts enjoy the challenge of refurbishing these vintage regulators, bringing them back to their original condition and occasionally using them for recreational dives.
The Broader Impact of the Mk II
The Essgee Aqualung Mk II represents more than just a piece of equipment; it symbolizes a pivotal moment in the history of diving. Its development reflects the rapid advancements in technology during the mid-20th century and the growing popularity of scuba diving as a recreational and professional activity. By addressing the limitations of earlier designs and incorporating forward-thinking features, Siebe Gorman helped pave the way for the modern regulators we use today.
The Mk II also highlights the importance of collaboration and innovation in the diving industry. Siebe Gorman’s partnership with La Spirotechnique allowed the company to leverage existing technology while adding its unique contributions. This approach demonstrated the value of cross-cultural and interdisciplinary collaboration.
Conclusion
The Siebe Gorman Essgee Aqualung Mk II is a landmark in the history of scuba diving equipment. Its innovative design, improved performance, and historical significance make it a fascinating subject for diving enthusiasts and historians alike. As a rare collector’s item, the Mk II continues to inspire admiration and respect, reminding us of the ingenuity and determination that characterized the early days of underwater exploration.
For those interested in the history of diving, the Mk II serves as a compelling example of how technology can evolve to meet the needs of adventurous spirits seeking to explore the depths of the ocean. Its legacy endures, not only in the collections of vintage scuba enthusiasts but also in the hearts of those who appreciate the rich history of diving.
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