Machine Support gained valuable experience with the installation of water jets on all four MEKO® A-200 Patrol Corvettes from the South African Navy. These four Wärtsilä propulsion jets are the largest water jets ever built. The first part of this job at Germany's Blohm + Voss yard involved the transportation and building up of a hydraulic heavy lift, necessary for getting all the parts of the water jet in place. This lift can be controlled very accurately in every direction, by moving its four hydraulic legs separately in height or all together in a forward or backward direction.
After the lift was in position a mobile machining tool with a diameter of more than 11ft (3,5m) was set up, which was then used to machine the water jet flange contact area. During this stage the use of laser alignment equipment was vital to ensure the necessary accuracy. Next involved the placement of the gauge for drilling the 40 M76 bolt holes, which are necessary to secure the seat ring and stator bowl. For the exact positioning a laser alignment system was used, which shows precise movements while controlling the hydraulic heavy lift. A smart horizontally placed drill unit makes it possible to make the bolt holes very fast and neat.
Then it became time to put the heavy parts of the water jet in place. The heaviest part from the installation is the stator bowl with reversing bucket. This reversing bucket makes it possible to make emergency stops within two boat lengths from going full speed. Second in weight is the driving shaft, weighing 14.5 t. The hydraulic heavy lift can hold these parts easily, with a maximum load capacity of 20 t. After all parts were secured and tightened the water jet installation was finished.
The services from Machine Support on these 396ft (121m) MEKO® Corvettes did not end with the water jets. After installing the water jets, Machine Support did the alignment, chocking and mounting of the gearboxes, support bearings and gas turbines (20,000kW) on board. After sea test trials the patrol corvettes were delivered to the South African Navy. Now they are used in the way they were build for, going over 27 knots!
