Single-weight cable light Derrick generally uses the joint operation of two rods, each one of the derrick only one of the rope, one of the hanger rod layout. On the outboard, the other is arranged above the hatch.
Between the two suspenders by the hanging rod between the cable (middle stable cable) connected, the derrick is fastened to the side eye ring with the Derrick two side boom, so that the two rods are fixed in the desired position, as shown in Figure 1. In unloading, you can use the Fender hoist winch into the hanging cable, the cargo from the cabin to hoist the hatch after a certain height, then use the outboard Derrick hoist winch into the hanging cable, at the same time loose the hanging cable of the fender, so that the goods hang to the outboard, and then two of the cable at the same time loose, unloading the goods. The order of operation of loading is opposite to unloading.