Jackup Rig: Béda antarrépisi

Hiji '''jack-up rig''' atawa hiji unit anu bisa naék sorangan ''(self-elevating)'' nyaéta jenis anjungan usik anu diwangun tina [[Hull (watercraft)|lambung]] ngambang dilengkepan kalayan sajumlah suku nu bisa usik,is a type o fitted with a number of movable legs, sanggup naékeun lambung di luhureun permukaan sagara. Lambung apung matak unit bisa ngangkut sarta kabéh mesin kapasang ka lokasi anu dipikahayang. Sanggeus di lokasi lambung ditaékkeun nepikeun ka posisi anu diperlukeun di luhur permukaan sagara dirojong ku sukuna anu nicak kana dasar sagara. Suku ti unit éta bisa dirarancang pikeun nembus dasar sagara, bisa dilengkepan bagéan rada ngagedéan atawa mangrupa pondasi. <ref>{{cite book|title=RULES FOR BUILDING AND CLASSING MOBILE OFFSHORE DRILLING UNITS|year=2008|publisher=American Bureau of Shipping|pages=3.1.1 Page 5|url=www.eagle.org}}</ref> Umumna rig Jack-up henteu bisa [[Marine propulsion|maju sorangan]] gumantung kana [[Tugboat|kapal]] atawa [[Heavy lift ship|kapal angkat beurat]] pikeun transportasi.

Jack-up rigs are so named because they are self-elevating—with three or four movable legs that can be extended (“jacked”) above or below the hull. Jack-ups are towed to the site with the hull, which is actually a water-tight barge that floats on the water’s surface, lowered to the water level, and the legs extended above the hull. When the rig reachesréaches the drill site, the crew jacks the legs downward through the water and into the seaséa floor (or onto the seaséa floor with mat supported jack-ups). This anchors the rig and holds the hull well above the waves.

A jackup is a floating barge fitted with long support legs that can be raised or lowered. The jackup is maneuvered (self-propelled or by towing) into location with its legs up and the hull floating on the water. Upon arrival at the work location, the legs are jacked down onto the seafloorséafloor. Then "preloading" takes place, where the weight of the barge and additional ballast water are used to drive the legs securely into the seabottomséabottom so they will not penetrate further while operations are carried out. After preloading, the jacking system is used to raise the entire barge above the water to a predetermined height or "air gap", so that wave, tidal and current loading acts only on the relatively slender legs and not on the barge hull.

Modern jacking systems use a [[rack and pinion]] geargéar arrangement<ref>[http://www.gustomsc.com/attachments/150_GustoMSC%2006.103%20-%20Jacking%20systems%20RP.pdf Rack and Pinion jacking system example]</ref> where the pinion gearsgéars are driven by hydraulic or electric motors and the rack is affixed to the legs.

This type of rig is commonly used in connection with [[Oil platform|oil and/or natural gas drilling]]. There are more jackup rigs in the worldwide offshore rig fleet than other type of mobile offshore [[drilling rig]]. Other types of offshore rigs include [[semi-submersibles]] (which float on pontoon-like structures) and [[drillship|drillships]]s, which are ship-shape vessels with rigs mounted in the centers. These rigs drill through holes in the drillship hulls, known as moon pools.

File:NewCarissa dismantled by KarlissaA and B July 2008 panorama merge.jpg|Jackup barges being used to dismantle a ship that was wrecked at seaséa.

[[CategoryKategori:Oil platforms]]

[[CategoryKategori:Ship types]]