BOPs on offshore rigs are mounted below the rig deck. Blowout preventers are used on land wells, offshore rigs, and subsea wells. Marine engineers are also responsible for building and maintaining offshore oil rigs. Simple hydraulic dredging rigs on small barges did the work. A derrick helps pump oil in most offshore rigs. This is also used on some offshore oil and gas rigs. This type of construction is already used for offshore oil rigs. Square-rigged sails are also less prone to broaching when running than Bermuda rigs. Lasers can be rigged with a variety of rigs. The security of more than thirty offshore oil rigs in Malaysian waters are PASKAL's responsibility. Specialized jackup rigs (Turbine Installation Vessels) are used to install foundation and turbine. Tandem skydiving requires equipment with several differences from normal sport skydiving rigs. The first jackup rigs, for shallow waters, was built in 1954. Models were controlled using wires, poles and underwater tracks and rigs. The vessels employed would be classified as dhows with lateen rigs.