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Simulation study on the Influence of EEDI requirements to shiphandling in heavy weather

Nishizaki C., Okazaki T., Yabuki H., Yoshimura Y.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2019

Vol. 13. no. 4

855--860

In order to reduce the CO2 emission from ships, International Maritime Organization executes the restriction of Energy Efficiency Design Index (EEDI) which limits amount of CO2 when freight of one ton is carried at one mile. Although the realization of higher efficiency of main engine without reduction of engine output is the best solution, it might be impossible. To comply with the EEDI requirements, it is assumed that the ship’s engine power becomes smaller than the existing ship by means of improving the ship propulsive efficiency. However, shiphandling in rough seas is expected to become difficult when the engine power is reduced. In this paper it is shown that the influence of the degraded main engine exerts on the safety of shiphandling in heavy weather based on the simulation study. In these experiments, both the simulation model that decreased engine power corresponding to EEDI requirement and that with the conventional engine power were tested, and masters in active service maneuvered the test ships in the rough seas.

Improving the Efficiency of a High Speed Catamaran Through the Replacement of the Propulsion System

Melo G., Echevarrieta I., Serra J. M.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2015

Vol. 9, no. 4

531--535

The high speed vessels are primarily designed for short distances services as public transport of passengers and vehicles. The range of high speed, according to the Code of high-speed vessels begins at 20 knots, which depends on the cruise speed you desire for your vessel; you will have to use the most appropriate type of propellant. In general, in the past 20 years, they have been building high-speed vessels with speeds above 33 knots, which meant installing water jet propellants coupled to powerful engines and therefore of high consumption of fuel, increasing operating costs and causing increased air pollution. Although the prices of fuel have been reduced to half, due to the sharp fall in oil prices, the consumption of fuel and the air pollution remains high at these speeds and powers used, in addition to that the reduction of the time spent on each trip is not excessive, mainly in short routes that are less than an hour . This article is about adapting a ship of high-speed service, with a maximum speed in tests of 34 knots and to reduce its operating costs (fuel, maintenance, etc.) and make it economically viable; before the transformation, this vessel was operating with a service speed of 22 knots, and with a consumption per mile of 135 litters of MGO. The transformation process has consisted by: – Replacement of the two original water jet with four shaft lines with fix pitch propeller. – Replacement of the two original main engines (2 x 6500 kW = 13000 kW) by four engines (4 x 1380kW = 5.520 kW). – Changing the underwater hull shape to fit the new propellers and maximize its efficiency. – Relocation of auxiliary engines, to achieve the most efficient trim. – Installation of two lateral propellers to improve maneuverability and shorten the total time of journey. After the reform and the return to service of the vessel with a service speed of over 22 knots, it has been verified that the consumption per mile is of 45 litters MGO, representing a reduction of 65% of consumption and even more reduction of emissions as the new engines comply with the latest regulations.