A grooved defect of 0.43mm depth x 7mm width x 370mm length = 1/3 circle caused on crank shaft of 2700kW main diesel engine was found during CMS inspection of special survey dock. At first permanent repair by machining the crank pin to remove 1.0mm depth all around with fitting oversized crank pin metal have been discussed. However it is expected for 3 months at least to make up oversize crank pin metal. So, the vessel was sailed out after removing notches from the defect carefully with confirming safety condition by stress calculation with fatigue strength evaluation of the crank shaft contained the defect and checking lubricating flow condition. This time, its summary is shown in this paper.

This paper discusses a wireless power transfer system equipped with multiple coils for underwater vehicles.The system discussed in this paper includes dual-receiving coils mounted on underwater vehicles that can receive electric power at the same time,making it possible to expect an increase in transmission power and improved redundancy of the system.This paper examines receiving voltage,transmission power and power transmission efficiency when the coils are misaligned.The results of a test which used a 1.5-kW experimental system confirmed that the use of dual-receiving coils leads to a power transmission capacity with stable receiving voltage under a wide range of misalignment conditions compared with the case where a single receiver is utilized.

  In this study, cycle calculations were performed to investigate the characteristics of cycle thermal efficiency and turbine output in a power generation system using waste heat from a marine engine with HFO-1234yf as a working fluid.

  In the case that changes occurred in warm water temperature difference, turbine power output with regards to temperature difference of warm water denoted upwardly convex and took the maximum value at around 24 and 29 degrees of temperature difference. By way of comparison, calculations were carried out under equal conditions using HFC245fa, ammonia and isopentane as working fluids. In regard to turbine power output, HFO-1234yf, HFC-245fa and isopentane indicated almost the same value. On the other hand, ammonia showed higher value than HFO-1234yf, HFC-245fa and isopentane. When cold water temperature difference was changed, both thermal efficiency and turbine power output showed a decreasing tendency. The results showed that HFO-1234yf can replace HFC-245fa as a working fluid.