Siebe Gorman Helmet. #7055

Siebe Gorman Dive Helmet Specifications and Historical Significance

Dimensions and Materials

Height: 460 mm (measured from the base of the corselet to the highest point on the bonnet)
Width: 378 mm (measured between the two widest points of the bonnet and corselet)
Depth: 421 mm (measured from the most forward projection of the bonnet/corselet to the furthest rear projection)

Materials: Copper, brass, glass, lead solder, leather, plastic

Signature Marks:

Manufacturer’s plaque (center front of the corselet): SIEBE GORMAN & Co LTD SUBMARINE ENGINEERS LONDON (PATENT)
Outer rim of the front light (viewing window): -10227
Front brails (left to right): SIEBE GORMAN & Co LTD FRONT FRONT LONDON

Historical Background

Siebe Gorman Ltd stands out as a pioneer in diving and breathing equipment. Founded by Augustus Siebe and his son-in-law, Gorman, this British company focused on advancing commercial diving and marine salvage. Notably, Siebe Gorman promoted itself as ‘Submarine Engineers’ and revolutionized underwater exploration with the creation of the ‘closed’ diving helmet. Unlike previous ‘open’ helmet systems, this helmet was watertight and offered enhanced safety.

Evolution of the 12-Bolt Helmet

Siebe Gorman manufactured the 12-bolt helmet continuously from 1837 to 1975. This helmet is named for the bolts on the breastplate or corselet, which allowed divers to securely attach their rubber and canvas suits, ensuring a watertight seal. Consequently, divers could screw the top of the helmet in place and descend safely.

Many manufacturers around the world, including those in Korea, Japan, China, and Italy, adopted this design. Due to its simplicity and durability, the 12-bolt system became a widely used and reliable piece of diving equipment. Remarkably, it is still in use today.

Siebe Gorman Dive Helmet Collection: Celebrating History and Heroism

Explore our collection of Siebe Gorman dive helmets, each offering a unique story of underwater exploration and heroism. These helmets once belonged to a navy salvage diver who played a significant role in the Montebello nuclear tests of the 20th century.

Atomic Age Milestones

During the early 1950s, the Montebello Islands off the coast of Australia became a key site for British nuclear tests. On October 3, 1952, the UK conducted Operation Hurricane on the HMS Plym in Main Bay, Trimouille Island. This historic event marked the UK’s entry into the exclusive nuclear club with its first atomic weapon test.

Later, in 1956, the Montebello Islands were again the stage for British nuclear tests, codenamed “Mosaic G2”. This test, conducted on Trimouille and Alpha Islands, yielded 60 kilotons, making it the largest nuclear explosion ever in Australia. Moreover, the explosion left a significant fallout that affected areas as far away as Mount Isa, Julia Creek, Longreach, and Rockhampton.

Honoring Diver Heroism

This collection of Siebe Gorman dive helmets serves as a tribute to the bravery of the navy salvage diver who used them. These helmets symbolize the courage of those who faced challenging conditions and contributed to a pivotal chapter in world history.

Stay Tuned: We will soon share captivating photos of this extraordinary collection. Each helmet offers a visual journey into the innovation and history of Siebe Gorman dive helmets.