A Study on Tsunami Protection Measures of Mooring Vessels to a Wharf by Install More Mooring Tethers (Part 2)

When tsunami attacks a harbor, the vessels moored at the wharf are exposed to a risk. For example, the following damages are assumed; breaking the mooring tether, grounding on a wharf, drifting to land areas and destroying buildings. In the previous report, the motion analysis of mooring vessels in tsunamis and the usefulness of tsunami protection measures by the install more mooring tethers (IMMT) was described using the MPS method. The incident wave angles of tsunami were used the 0 degrees (longitudinal wave) and 90 degrees (Transverse wave). For any incident angles, IMMT was effective. However, in the case of transverse wave of wave height 6.0m or more, it is possible to prevent the break of the mooring tethers, but it was confirmed that the vessels damaged by the grounding on a wharf. In the case of longitudinal wave, IMMT confirmed that it did not affect in some cases. It is influenced by the direction the mooring tether pulls. When the vessel moves, there are mooring tethers that are pulled or slacked. As a result, the mooring force does not act equally on the mooring tethers. Also, as an issue of existing papers, studies on oblique waves were not done. It is important to solve these issues.