M.A.N. To Build Three Floating Cranes With Voith-Schneider Propulsion
The Saudi Ports Authority recently awarded M.A.N, in Nuremburg, West Germany, as general contractor, an order for three floating cranes with a lifting capacity of 200-tons each.
The pontoons are being constructed by M.A.N.-GHH Dock and Shipbuilding Company. They measure: length 60 meters, breadth 21.7 meters, trial run draft 2.38 meters, with a displacement of about 2,150 tons.
Like the two 200-ton floating cranes Dammam and Jeddah that are already in service, the new cranes are designed to operate without tug assistance. They will be equipped with Voith-Schneider propulsion systems.
The cranes are to be used in the ports of Jeddah, Jubail, and Gizan. Depending on the amount of work to be performed, it is planned to transfer the cranes from port to port without tug assistance. In view of the relatively high free-running speed of about 8 knots, a three-propeller system was selected.
The total input power of each crane is 1,640 kw, distributed over two size 21 G 11/135 propellers, each of 600 kw, and a size 18 G 11/115 VS propeller of 440 kw.
The propellers are driven electrically by three-phase a.c. squirrel- cage motors. To utilize the installed power as ideally as possible for maneuvering and for the compensation of wind forces, the two larger propellers are arranged at the crane-mast end of the pontoon, i.e., near the center of the lateral windage area. These are located in recesses. The third propeller is installed freely in the raised pontoon bottom.