Effective Combination of Energy Saving Devices

In recent years, ship owners have come to seek a more fuel-efficient ship operation at lower cost. In addition, since the start of the EEDI regulations, the shipyard has begun to focus on the further development of high performance ships. In such a background, many ship designers and manufacturers developed a variety of products such as the propeller cap with fin, rudder bulb and duct. On the other hand, when the ship is installed with several energy saving devices, the reduction amounts of the fuel consumption from synergistic effects are sometimes unclear at the design stage. These issues are highly complicated because designs of those energy saving devices are different and moreover the detail profiles of energy saving devices are confidential. Therefore, it is very difficult to evaluate the total performance at the design stage. However, Nakashima propeller CO., LTD produces not only the high performance propeller, it is also feasible to design of energy saving devices such as ECO-Cap which is a propeller cap with fins (Okada, et al. 2013), Ultimate Rudder Bulb (Okada, et al. 2015) and Neighbor Duct (Katayama, et al. 2017). In this paper, the authors conducted the model tests for three kinds of energy saving devices by using the model ship of 82kBC. Furthermore, the different combinations were carried out in model tests and CFD analysis. This paper summarizes the synergistic effect of energy saving devices on the basis of the model test and CFD results.