The name of this rig implies exactly what it does. Jack-ups are towed to their location where rig personnel use heavy machinery to jack the legs down into the water until they are on the ocean floor. When this is competed, the platform containing the work area rises above the water. After the platform his risen about 50 feet out of the water, the rig is ready to begin drilling. Jack-up rigs are limited to a water depth of about 600 feet or less.
Photo by Ron Edwards