Development of Simple Holding Device with Net Chain Applying to Wave-dissipating Blocks, Floats and Sinking Objects of Various Shapes

Abstract

A device for transferring wave-dissipating blocks was developed using net chains to allow for automation and labor saving. The device spreads net chains over a block and then tightens the net chains using a wire rope connected to a crane to lift the block. A model device was used to conduct a transfer experiment under several visibility conditions. A practical device was produced, and transfer work was done. The results showed that by adjusting work conditions, the working time efficiency under good visibility situations is 3 min./piece and that for poor visibility situations is about 4-6 min./piece. The cost for transferring a block is about 1/3 of the conventional manual method. This device can be used for blocks buried in sand and things of various shape.