Kentledge (fr. ''ballast''), or kentledge weights, are slabs or blocks of concrete or iron (usually

pig iron Pig iron, also known as crude iron, is an intermediate product of the iron industry in the production of steel which is obtained by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with sil ...

, sometimes with a cast-in handle for assist moving). They are used within ships or boats as permanent, high-density

ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship, ...

. They may also be used as

counterweight A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less wea ...

s in cranes such as

tower crane A crane is a type of machine, generally equipped with a hoist rope, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy objects and transport ...

s or

swing bridge A swing bridge (or swing span bridge) is a movable bridge that has as its primary structural support a vertical locating pin and support ring, usually at or near to its center of gravity, about which the swing span (turning span) can then p ...

s as is found in the

Victoria Swing Bridge The Victoria Swing Bridge is a swing bridge in Leith, Edinburgh. History The dock upstream from the bridge was begun in 1833, but financial troubles meant it was only finished between 1869 and 1875, and is nearly rectangular with a quayage of ...

. On construction sites, prior to the erection of a building,

static load testing Static load testing is an ''in situ'' type of load testing used in geotechnical investigation to determine the bearing capacity of deep foundations prior to the construction of a building. It differs from the statnamic load test and dynamic load te ...

may use a large number of kentledge stacked onto a platform. This platform is used to drive

piles Hemorrhoids (or haemorrhoids), also known as piles, are vascular structures in the anal canal. In their normal state, they are cushions that help with stool control. They become a disease when swollen or inflamed; the unqualified term ''hemo ...

into the ground beneath to test the integrity of the foundation.https://www.dot.ny.gov/divisions/engineering/technical-services/technical-services-repository/GCP-18b.pdf

References

{{Geotechnical engineering Mechanisms (engineering) Watercraft components