Editing Diving weighting system (section)

{{Short description|Ballast carried to counteract buoyancy}}
{{redirect|Weight belt|the belt used to support the torso during strength training|Weight lifting belt}}
{{use dmy dates|date=April 2023}}
{{Infobox diving equipment
|name         =
|image        = Zavorra.JPG
|alt          = <!-- Wikipedia:Alternative text for images -->
|caption      = Conventional scuba weight-belt with quick-release buckle
|acronym      =
|other_names  = {{ubl|Dive weights|Weight-belt|Integrated weights|Trim weights}}
|uses         = Buoyancy correction and trim adjustment of underwater divers
|inventor     =
|manufacturer =
|model        =
|related      = [[Buoyancy compensation device]]
}}
[[File:diving lifting system - Weight belts.JPG|thumb|right|A bag weight belt and a traditional weight belt]]
A '''diving weighting system''' is ballast weight added to a diver or diving equipment to counteract excess buoyancy. They may be used by divers or on equipment such as diving bells, submersibles or camera housings.

Divers wear '''diver weighting systems''', '''weight belts''' or '''weights''' to counteract the [[buoyancy]] of other [[diving equipment]], such as [[diving suit]]s and aluminium [[diving cylinder]]s, and buoyancy of the diver. The scuba diver must be weighted sufficiently to be slightly negatively buoyant at the end of the dive when most of the breathing gas has been used, and needs to maintain neutral buoyancy at safety or obligatory decompression stops. During the dive, buoyancy is controlled by adjusting the volume of air in the [[buoyancy compensation device]] (BCD) and, if worn, the [[dry suit]], in order to achieve negative, neutral, or positive buoyancy as needed. The amount of weight required is determined by the maximum overall positive buoyancy of the fully equipped but unweighted diver anticipated during the dive, with an empty buoyancy compensator and normally inflated dry suit. This depends on the diver's mass and body composition, buoyancy of other diving gear worn (especially the [[diving suit]]), water [[salinity]], weight of breathing gas consumed, and water temperature. It normally is in the range of {{convert|2|kg|lb}} to {{convert|15|kg|lb}}. The weights can be distributed to trim the diver to suit the purpose of the dive.

Surface-supplied divers may be more heavily weighted to facilitate underwater work, and may be unable to achieve neutral buoyancy, and rely on the diving stage, bell, umbilical, lifeline, shotline or jackstay for returning to the surface.

Freedivers may also use weights to counteract buoyancy of a wetsuit. However, they are more likely to weight for neutral buoyancy at a specific depth, and their weighting must take into account not only the compression of the suit with depth, but also the compression of the air in their lungs, and the consequent loss of buoyancy. As they have no decompression obligation, they do not have to be neutrally buoyant near the surface at the end of a dive.

If the weights have a method of quick release, they can provide a useful rescue mechanism: they can be dropped in an emergency to provide an instant increase in buoyancy which should return the diver to the surface. Dropping weights increases the risk of [[barotrauma]] and [[decompression sickness]] due to the possibility of an uncontrollable ascent to the surface. This risk can only be justified when the emergency is life-threatening or the risk of decompression sickness is small, as is the case in freediving and scuba diving when the dive is well short of the no-decompression limit for the depth. Often divers take great care to ensure the weights are not dropped accidentally, and heavily weighted divers may arrange their weights so subsets of the total weight can be dropped individually, allowing for a somewhat more controlled emergency ascent.

The weights are generally made of [[lead]] because of its high [[density]], reasonably low cost, ease of [[casting]] into suitable shapes, and resistance to [[corrosion]]. The lead can be cast in blocks, cast shapes with slots for straps, or shaped as pellets known as "[[lead shot|shot]]" and carried in bags. There is some concern that lead diving weights may constitute a [[Lead poisoning|toxic hazard]] to users and environment, but little evidence of significant risk.