Editing Diving weighting system (section)

==Types of weight==
All or part of the weighting system may be carried in such a way that it can be quickly and easily jettisoned by the diver to increase buoyancy, the rest is usually attached more securely.

===Ditchable weights===
[[Freediving|Breathhold]] and [[Scuba diving|scuba divers]] generally carry some or all of their weights in a way that can be quickly and easily removed while under water. Removal of these weights should ensure that the diver can surface and remain positively buoyant at the surface. The technique for shedding weights in an emergency is a basic skill of scuba diving, which is trained at entry level. Research performed in 1976 analyzing diving accidents noted that in majority of diving accidents, divers failed to release their weight belts.<ref name=RRR6232 /> Later evaluations in 2003 and 2004 both showed that failure to ditch the weight remained a problem.<ref name=RRR7763 /><ref name="R1538" />

====Weight belt====
Weight belts are the most common weighting system currently in use for [[recreational diving]].<ref name="ygraine" /> Weight belts are often made of tough [[nylon]] webbing, but other materials such as [[rubber]] can be used. Weight belts for scuba and breathhold diving are generally fitted with a quick release buckle to allow the dumping of weight rapidly in an emergency.<ref name="BSAC manual" />

A belt made of rubber with traditional pin buckle is called a ''Marseillaise belt''.<ref name="decathlon" /><ref name="spearfishingworld" /> These belts are popular with [[Freediving|freedivers]] as the rubber contracts on descent as the [[diving suit]] and [[lungs]] are compressed, keeping the belt tight throughout the dive.<ref name="renepotvin" />

The most common design of weight used with a belt consists of rectangular [[lead]] blocks with rounded edges and corners and two slots in them threaded onto the belt. These blocks can be coated in [[plastic]], which further increases corrosion resistance. Coated weights are often marketed as being less abrasive to [[wetsuits]]. The weights may be constrained from sliding along the webbing by the use of metal or plastic [[Glossary of underwater diving terminology#belt slider|belt sliders]]. This style of weight is generally about {{convert|1 to 4|lb|kg}}. Larger "hip weights" are usually curved for a better fit, and tend to be {{convert|6 to 8|lb|kg}}. 

Another popular style has a single slot through which the belt can be threaded. These are sometimes locked in position by squeezing the weight to grip the webbing, but this makes them difficult to remove when less weight is needed.

There are also weight designs which may be added to the belt by clipping on when needed.
Some weightbelts contain pouches to contain lead weights or round [[lead shot]]: this system allows the diver to add or remove weight more easily than with weights threaded onto the belt. The use of shot can also be more comfortable, as the shot conforms to the diver's body. Weight belts using shot are called '''shot belts'''. Each shot pellet should be coated{{clarify|date=February 2016}}<!--coated with what? Copper and nickel plated shot is available but any scratch through the plating would set up a galvanic cell and accelerate corrosion --> to prevent corrosion by sea water, as use of uncoated shotgun shot for sea diving would result in the lead eventually corroding into powdery [[Lead(II) chloride|lead chloride]]
<gallery>
File:Taucherblei.JPG|Solid belt weight and pouches holding lead shot for scuba diving
File:Aa scuba shotbelt.jpg|shot belt, and lead-shot-filled anklet, and foot rulers for scale
File:Aa weightsandbelts.jpg|scuba diving weights and weightbelts
File:Scuba diving weight.jpg|3 kilogram scuba diving hip weight, curved for better fit
File:Plumbum weight, 3kg (diving).jpg|3 kilogram compact scuba diving weight
File:Dive weights - 500g Bright Weights P8160081.jpg|Dive weights - 500g Bright Weights - small lead weights with plastic coating
</gallery>

====BCD integrated weights====
<!-- target for redirect [[Integrated dive weights]], [[Integrated weight system]], [[Integreated weights]] -->
These are stored in pockets built into the [[Buoyancy compensator (diving)|buoyancy control device]]. Often a [[velcro]] flap or plastic clip holds the weights in place. The weights may also be contained in zippered or velcroed pouches that slot into special pockets in the BCD.  The weight pouches often have handles, which must be pulled to drop the weights in an emergency or to remove the weights when exiting the water. Some designs also have smaller "trim pouches" located higher in the BCD, which may help the diver maintain neutral attitude in the water. Trim pouches typically can not be ditched quickly, and are designed to hold only 1-2 pounds (0.5–1&nbsp;kg) each. Many integrated systems cannot carry as much weight as a separate weight belt: a typical capacity is 6&nbsp;kg per pocket, with two pockets available.<ref>[http://www.mares.com/lab_detail.php?id=73&region=ALL Mares – stand for diving<!-- Bot generated title -->] {{webarchive |url=https://web.archive.org/web/20080415175444/http://www.mares.com/lab_detail.php?id=73&region=ALL |date=April 15, 2008 }}</ref> This may not be sufficient to counteract the buoyancy of dry suits with thick undergarments used in cold water.

Some BCD harness systems include a crotch strap to prevent the BCD from sliding up the wearer when inflated, or down when inverted, due to the weights.

====Weight harness====
A weight harness usually consists of a belt around the waist holding pouches for the weights, with shoulder straps for extra support and security. Often a velcro flap holds the weights in place. They have handles, which must be pulled to drop the weights in an emergency  or to remove the weights when exiting the water. A weight harness allows the weights to be comfortably carried lower on the body than a weight belt, which must be high enough to be supported by the hips. This is an advantage for divers who have no discernible waist, or whose waist is too high to trim correctly if a weight belt is worn. These advantages may also be available on some styles of integrated BC weights. A weight harness may also incorporate a crotch strap or straps to prevent weight shift if the diver is in a steep head down posture.

====Clip-on weights====
<!-- target for redirect [[Clip-on weight]] -->
[[File:Clip-on diving weight front view DSC04180small.jpg|thumb|upright=0.5|Clip-on trim weight on harness webbing (front view showing D-ring)]][[File:Draeger clip-on diving weight DSC03652.JPG|thumb|upright=0.5|Lead clip-on diving weight by Draeger with bronze spring clip, c. 1980]]
These are weights which attach to the harness directly, but are removable by disengaging the clip mechanism. They can also be used to temporarily increase the weight of a conventional weight belt. Various sizes have been available, ranging from around 0.5 to 5&nbsp;kg or more. The larger models are intended as ditchable primary weights, and are used in the same way as BCD integral weights or weight harness weighs, but clipped to the backplate or sidemount harness webbing, and the smaller versions are also useful at trim weights.

====Backpack weight pouch====
Some [[rebreather]]s (e.g. the [[Siebe Gorman CDBA]]) have a pouch containing lead balls each a bit over an inch diameter. The diver can release them by pulling a cord.

===Fixed weights===
[[Surface-supplied diving|Surface-supplied divers]] often carry their weights securely attached to reduce the risk of accidentally dropping them during a dive and losing control of their buoyancy. These may be carried on a weight belt with a secure buckle, supported by a weight harness, connected directly to the diving safety harness, or suspended from the [[Glossary of underwater diving terminology#corselet|corselet]] of the helmet. Heavily [[Weighted shoes (diving)|weighted footwear]] may also be used to stabilise the diver in an upright position.

In addition to the weight that can be dropped easily ('ditched'), some scuba divers add additional fixed weights to their gear, either to reduce the weight placed on the belt, which can cause lower back pain, or to shift the diver's center of mass to achieve the optimum position in the water.
* '''Tank weights''' are attached to the diving cylinder to shift the center of mass backward and towards the head or feet, depending on placement.
** '''V-weights''' are long, narrow, weights which are carried in the groove between twinned cylinders. They may be carried singly or as a pair. Traditionally wedge sectioned lead castings, but also found in solid cylindrical format and as long narrow webbing weight pockets filled with shot.<ref name="Tecsysteme" /><ref name="DIRzone" />
** '''Tank trim weights''' are smaller weights , usually strapped towards the base of an aluminium cylinder to prevent it from trimming  base-upward in seawater when side- or sling-mounted,  when the gas is used up.
* '''Ankle weights''', which are typically about 1&nbsp;lb./0.5&nbsp;kg of shot, are used to counteract the positive buoyancy of [[diving suit]] leggings, made worse in drysuits by the migration of the internal bubble of air to the feet, and positively buoyant [[Swimfin|fins]]. Some divers prefer negatively buoyant fins. The additional effort needed when finning with ankle weights or heavy fins increases the diver's gas consumption.
* '''[[Backplate and wing|Metal backplates]]''' made from stainless steel, which may be used with [[Backplate and wing|wing style buoyancy compensators]], move the center of mass upward and backward. Some backplates are fitted with an additional weight, often mounted in the central channel, also called a keel weight or a p-weight.<ref name="Tecsysteme" />
* '''[[Diving cylinder|Steel diving cylinders]]''' are preferred over aluminium cylinders by some divers—particularly cold water divers who must wear a suit that increases their overall buoyancy—because of their [[Diving cylinder#Buoyancy characteristics |negative buoyancy]]. Most steel tanks stay negatively buoyant even when empty, aluminium tanks may become positively buoyant as the gas they contain is used. High-pressure (300bar) steel tanks are significantly negative.

<gallery>
Image:Aa shotbelt.jpg|Shot belt for scuba diving
Image:Aa leadshotanklets.jpg|Lead shot anklets for scuba diving
Image:Aa weightsandbelts.jpg|Diving weights and belts, showing two sorts of belt clip
Image:Weight-belt.jpg|A diving weight harness system with integrated weight pockets
File:Baudrier artisanal de chasse sous marine.jpg|Freediving weight harness for spearfishing
File:Clip-on diving weight back view DSC04182small.jpg|Clip-on trim weight on harness webbing (back view showing shock cord gripping webbing)
File:Draeger clip-on diving weight DSC03662.JPG|Draeger clip-on weight showing clip mechanism
File:Diving safety harness with weight pocketsPA268045.jpg|A diver's safety harness with removable weight pockets, used for surface-supplied diving
File:Block clip-on diving weight P6045427.JPG|Clip-on main dive weight using a belt bracket and spring clip retainer
File:Block clip-on diving weight P6045428.JPG|Clip-on main dive weight showing the belt bracket and spring clip retainer
File:Block clip-on diving weight P6045431.JPG|Clip-on monolithic block type main dive weight front view
File:Block clip-on diving weight P6045433.JPG|Clip-on monolithic block type main dive weight showing the hinged grip plate and shock cord retainer
File:Block clip-on diving weight P6045438.JPG|Clip-on monolithic block type main dive weight back view
File:Travel clip-on dive weight P6045453.JPG|Clip-on assembled main dive weight using a hinged grip plate and shock cord retainer. The support framework is designed to be lightweight for travel and can carry a wide range of standard weight types.
File:Dive weights - Tubular and rectangular shot bags and cylindrical tank weights P8160083.jpg|Dive weights - Tubular and rectangular shot bags and cylindrical tank weights
</gallery>