The IMO adopted a revision of MARPOL Annex VI to apply the Energy Efficiency Design Index (EEDI) to newly built ships in July 2011. The target EEDI will be tightened incrementally until 2025. The Energy Efficiency Existing Ship Index (EEXI) was also introduced to existing vessels in June 2021. Ship hull roughness is one of the most important factors that affect ship resistance and efficiency. In this study, portable 3D hull roughness measurement equipment was developed. A method to estimate friction resistance added by hull roughness was devised by using a cylinder test, which can reproduce the speed of a ship in service. The projected area of the “cones” above the non-effective thickness δs to stream direction per unit area which is called the cone projected area (CPA), was calculated using the roughness parameter Rc (i.e.,the average height of roughness components) and the wavelength parameter RSm (i.e., the average length of roughness components). A strong positive correlation was confirmed between the friction increase rate FIR (%) and CPA. Using this relationship, a friction resistance increase caused by “wavy roughness” or roughness of a paint film on a hull in service can be easily estimated from Rc, RSm and δs.
The authors initially investigated an engine system with an LPG reformer and its response to load fluctuations, but failed to fully examine how to optimize marine equipment aboard an LPG carrier and relevant safety requirements. Therefore, we started designing an LPG transport vessel with an LPG reformer in partnership with a shipyard, a tank manufacturer, and a ship owner. Through this process, we clarified various requirements for the designing and equipment of this LPG carrier and ways to resolve technical challenges. In this paper, we will give an outline of LPG reforming technology and introduce specific engineering associated with the installation of this technology. After completion, the LPG carrier equipped with the LPG reformer was awarded the Marine Engineering of the Year 2020.
Exhaust gas from ships becomes a problem as a causative substance of air pollution. Scrubber water is used for EGR that is an exhaust gas purifying device to absorb harmful matter. However, it cannot be reused since its alkalinity decreases after absorbing SOx. Therefore, an electrolytic device with Mg electrodes connected in series was developed. In this report, the current as a function of the applied voltage and the voltage between electrodes were measured. We also investigated the effect of the electrolytic device connected in series by comparing its alkalinity and energy efficiency with those of a device connected in parallel. It was shown that the output voltage from a power supply was divided between electrodes. The energy efficiency of the former device was equivalent to that of the latter. In the case of a 6.5 MW engine, the voltage and current of the later device were estimated as 7.9 V and 468 A, respectively. On the other hand, those of the former were 79 V and 46.8 A.
The work of an operator on board a ship is changing from technical tasks to those more clerical and administratively demanding. This transformation is well underway because of developments in automation. The automation is bringing more sensors into the system; this leads to an increasing number of alarms stored in the engine control console. Reducing the number of crew and officers as a result of the automation to increase efficiency makes the operator workload increase, especially in troubleshooting conditions. Improvement in an alarm system for the engine control console is a proposal to reduce the operator workload and support their decision-making process. To understand current conditions in alarm systems, three years of alarm data from our training ship’s engine control console was recovered and analyzed. We conclude that the alarm rate, the number of alarms per interval time, is low and acceptable in light of alarm management guidelines. We also found a large number of false alarms associated with sensor trouble. The exposure to such a number of false alarms leads to operator distrust of the alarm system, known as a cry-wolf syndrome. Improvement in the alarm system will bring a reasonable response rate of troubleshooting to the alarms.
During the past years, in response to the gradually stringent regulations, the undertaken steps in the shipping industry spurred the technological improvement in ship and engine designs. Thus, new engines accept a wide variety of fuels, and electronic systems provide flexible control and online tuning. At the same time, simultaneous assessment of performance and condition monitoring is becoming increasingly important. In this respect, digitalization and the accompanying evolution of smart sensors and data acquisition systems give the possibility of applying complex analytics and machine learning algorithms to the compelling need of engine performance monitoring and failure identification. The present paper proposes a solution to the problem of condition monitoring using a method of statistical analysis of multidimensional information acquired from the sensors. The factor analysis method is used to derive a performance index showing engine state deviation from the normal condition. At the same time, principal factor loadings are used as features characterizing the contribution of every measured and analyzed parameter to the variance of the performance index. The benchmark of the developed method is illustrated using the simulation model of a diesel engine with incorporated models of failure states. The latter was developed and validated from the data measured on the test engine.