The old copper Karlskrona diving helmet was not built in Sweden, most of them are originally german diving helmets which were converted by the swedish navy at their base in Karlskrona. Different versions exist: the older ones were Ludwig von Bremen ( later Hanseatische Apparatebau Gesellschaft vorm. L.v. Bremen ) 3 bolt helmets which were converted with 12 bolt breastplates. Later also standard Siebe Gorman helmets were equipped with ‘Zetterstrom’ exhaust valves and Hagenuk top windows. The most common ‘Karlskrona’ helmet is the M42 helmet which was built ( in 1942 ) by using HAGENUK bonnets from 3 bolt helmets to be rebuilt into 12 bolt helmets. Karlskrona helmets have only been supplied to the Swedish navy and have never been sold to the public which makes them extremely rare. The helmets are still used for training at the Navy Diving School in Karlskrona.

Photographs above: an early german ‘Ludwig von Bremen’ 3 bolt helmet converted to a 12 bolt helmet at the Karlskrona navy workshops.

Photographs above: a Siebe, Gorman & Co Ltd 12 bolt helmet modified with a ‘Zetterstrom’ exhaustvalve, a different telephone connector and a Hagenuk top window at the Karlskrona navy workshops.

The photograph above shows a drawing which explains how to convert the Karlskrona Model ÖVK-42 helmet with a Siebe Gorman & Co Ltd divers telephone. The drawing is dated 1963.