page_title: Surface-supplied diving
section_title: Corselet
hierarchical_section_title: Surface-supplied diving / Breathing apparatus / Free flow helmet / Standard diving helmet (Copper hat) / Corselet
caption_attribution_description: Slovenščina: Gradbišče hidroelektrarne Ožbalt, potapljača English: Divers Leon Nalaslovski (right) and Anton Hajdinjak at the Ožbalt hydroelectric power plant construction site.
context_page_description: Surface-supplied diving is diving using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel, sometimes indirectly via a diving bell. This is different from scuba diving, where the diver's breathing equipment is completely self-contained and there is no link to the surface. The primary advantages of conventional surface supplied diving are lower risk of drowning and considerably larger breathing gas supply than scuba, allowing longer working periods and safer decompression. Disadvantages are the absolute limitation on diver mobility imposed by the length of the umbilical, encumbrance by the umbilical, and high logistical and equipment costs compared with scuba. The disadvantages restrict use of this mode of diving to applications where the diver operates within a small area, which is common in commercial diving work.
context_section_description: The corselet, also known as a breastplate, is an oval or rectangular collar-piece resting on the shoulders, chest and back, to support the helmet and seal it to the suit, usually made from copper and brass, but occasionally steel. The helmet is usually connected to the suit by placing the holes around the rubberised collar of the suit over bolts along the rim of the corselet, and then clamping the brass straps known as brailes against the collar with wing nuts to press the rubber against the metal of the corselet rim to make a  water-tight seal. An alternative method was to bolt the bonnet to the corselet over a rubber collar bonded to the top of the suit.
  Most bonnets are joined to the corselet by 1/8th turn interrupted thread. The helmet neck thread is placed onto the neck of the corselet facing the divers left front, where the threads do not engage, and then rotated forward, engaging the thread and seating on a leather gasket to make a watertight seal. The helmet usually has a safety lock which prevents the bonnet from rotating back and separating underwater. Other styles of connection are also used, with the joint secured by clamps or bolts (usually three). Some helmets were made with the bonnet and corselet in one piece and secured to the suit in other ways.
caption: Corselet showing interrupted thread for helmet connection and brailes clamping it to the suit. 12-bolt in background, 6-bolt in foreground.
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