page_title: Diving bell
section_title: Wet bell
hierarchical_section_title: Diving bell / Mechanics / Wet bell
caption_attribution_description: English: Open diving bell on a stern mounted bracket Dansk: Halv-åben dykkerklokke i hæk monteret slæde
context_page_description: A diving bell is a rigid chamber used to transport divers from the surface to depth and back in open water, usually for the purpose of performing underwater work. The most common types are the open-bottomed wet bell and the closed bell, which can maintain an internal pressure greater than the external ambient. Diving bells are usually suspended by a cable, and lifted and lowered by a winch from a surface support platform. Unlike a submersible, the diving bell is not designed to move under the control of its occupants, nor to operate independently of its launch and recovery system.
  The wet bell is a structure with an airtight chamber which is open to the water at the bottom, that is lowered underwater to operate as a base or a means of transport for a small number of divers. Air is trapped inside the bell by pressure of the water at the interface. These were the first type of diving chamber, and are still in use in modified form.
  The closed bell is a pressure vessel for human occupation, which may be used for bounce diving or saturation diving, with access to the water through a hatch at the bottom. The hatch is sealed before ascent to retain internal pressure.
context_section_description: A wet bell is a platform for lowering and lifting divers to and from the underwater workplace, which has an air filled space, open at the bottom, where the divers can stand or sit with their heads out of the water. The air space is at ambient pressure at all times, so there are no great pressure differences, and the greatest structural loads are usually self weight and the buoyancy of the air space. A fairly heavy ballast is often required to counteract the buoyancy of the airspace, and this is usually set low at the bottom of the bell, which helps with stability. The base of the bell is usually a grating or deck which the divers can stand on, and folding seats may be fitted for the divers' comfort during ascent, as in-water decompression may be long. Other equipment that is carried on the bell include cylinders with the emergency gas supply, and racks or boxes for tools and equipment to be used on the job. There may be a tackle for hoisting and supporting a disabled diver so that their head projects into the air space.
caption: Open diving bell on a stern mounted launch and recovery system
exif: {"Image ImageDescription": "", "Image Make": "SONY", "Image Model": "DSC-L1", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS2 Windows", "Image DateTime": "2007:10:07 21:08:24", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "256", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "838", "Thumbnail JPEGInterchangeFormatLength": "8318", "EXIF ExposureTime": "1/25", "EXIF FNumber": "51/10", "EXIF ExposureProgram": "Portrait Mode", "EXIF ISOSpeedRatings": "100", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2005:10:07 13:25:42", "EXIF DateTimeDigitized": "2005:10:07 13:25:42", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "8", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "3", "EXIF MeteringMode": "Spot", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "153/10", "EXIF SubSecTime": "250", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "469", "EXIF ExifImageLength": "551", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "712", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF SceneCaptureType": "Portrait", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}