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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

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2015

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Vol. 9, no. 4

531--535

EN

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.

2

Drag and Torque on Locked Screw Propeller

Tabaczek T., Bugalski T.

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

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2014

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Vol. 8, no. 3

441--447

EN

Few data on drag and torque on locked propeller towed in water are available in literature. Those data refer to propellers of specific geometry (number of blades, blade area, pitch and skew of blades). The estimation of drag and torque of an arbitrary propeller considered in analysis of ship resistance or propulsion is laborious. The authors collected and reviewed test data available in the literature. Based on collected data there were developed the empirical formulae for estimation of hydrodynamic drag and torque acting on locked screw propeller. Supplementary CFD computations were carried out in order to prove the applicability of the formulae to modern moderately skewed screw propellers.

3

Coefficients of Propeller-hull Interaction in Propulsion System of Inland Waterway Vessels with Stern Tunnels

Kulczyk J., Tabaczek T.

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

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2014

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Vol. 8, no. 3

377--384

EN

Propeller-hull interaction coefficients - the wake fraction and the thrust deduction factor - play significant role in design of propulsion system of a ship. In the case of inland waterway vessels the reliable method of predicting these coefficients in early design stage is missing. Based on the outcomes from model tests and from numerical computations the present authors show that it is difficult to determine uniquely the trends in change of wake fraction and thrust deduction factor resulting from the changes of hull form or operating conditions. Nowadays the resistance and propulsion model tests of inland waterway vessels are carried out rarely because of relatively high costs. On the other hand, the degree of development of computational methods enables’ to estimate the reliable values o interaction coefficients. The computations referred to in the present paper were carried out using the authors’ own software HPSDKS and the commercial software Ansys Fluent.

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A Step by Step Approach for Evaluating the Reliability of the Main Engine Lube Oil System for a Ship's Propulsion System

Anantharaman M., Khan F., Garaniya V., Lewarn B.

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

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2014

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Vol. 8, no. 3

367--371

EN

Effective and efficient maintenance is essential to ensure reliability of a ship's main propulsion system, which in turn is interdependent on the reliability of a number of associated sub- systems. A primary step in evaluating the reliability of the ship's propulsion system will be to evaluate the reliability of each of the sub- system. This paper discusses the methodology adopted to quantify reliability of one of the vital sub-system viz. the lubricating oil system, and development of a model, based on Markov analysis thereof. Having developed the model, means to improve reliability of the system should be considered. The cost of the incremental reliability should be measured to evaluate cost benefits. A maintenance plan can then be devised to achieve the higher level of reliability. Similar approach could be considered to evaluate the reliability of all other sub-systems. This will finally lead to development of a model to evaluate and improve the reliability of the main propulsion system.

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Using Reliability Block Diagrams and Fault Tree circuits, to develop a Condition Based Maintenance Model for a Vessel’s Main Propulsion System and Related Subsystems

Anantharaman M.

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

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2013

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Vol. 7, no. 3

409--413

EN

Merchant shipping has undergone a great transformation over the past three decades. The shipping market is highly competitive, which coupled with high crewing and fuel costs, leads to high operational costs. One of the paramount factor involved in vessel operation is the Maintenance cost and there is a dire need to keep this cost to a minimum. Fortunately the earlier policy of repair only maintenance in commercial shipping has been done away with, and was replaced by the policy of preventive maintenance. Planned Maintenance System was introduced by ship management companies in the early 90’s. Planned Maintenance offered benefits over the repair only policy, but has its own demerits. Many a time machinery equipment is opened up for routine maintenance after a specified time interval, irrespective of the need. This could lead to potential failures, which is explained by the fact that preventive maintenance resulted in meddling of a well set piece of machinery equipment, leading to its subsequent failure. This is where Condition based maintenance or CBM steps into prominence. CBM monitors the health of the machinery equipment, analyses the condition and helps you in decision making. The Main Propulsion system forms the heart of a vessel and we need to ensure its reliability, together with the reliability of its associated sub-systems. The entire system can be represented by reliability block diagrams, to show the interdependence of various components comprising the system. This helps in the decision making process of CBM whereby ship’s engineer may decide to stop the running machinery equipment, open and overhaul the same, else postpone the overhaul for a later safe date.