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The ship
Published in Alan E. Branch, Michael Robarts, Branch's Elements of Shipping, 2014
Alan E. Branch, Michael Robarts
Modern tonnage, particularly tankers, container ships and passenger liners, have transverse propulsion units in the bows, and these are termed bow thrusters. A number of vessels have side thrusters situated at the stern of the ship. Both bow and side thrusters are situated on the port and starboard sides. Their purpose is to give greater manoeuvrability in confined waters, e.g. ports, to reduce or eliminate the need for tugs. The rudder which enables the vessel to maintain its course is situated aft. Some ships have an additional rudder in the bows for easier manoeuvrability in port and these are generally found on ferries. A modern development is the Azipull or Azipod propulsion system. Stabilizers are in appearance similar to the fins of a fish, and are fitted to modern passenger liners and container ships to reduce rolling in heavy seas. They are fitted in pairs, and when in use protrude at right angles from the hull, deep below the water line. Their number depends on the size of the vessel. The provision of a bulbous bow can also improve passenger comfort, as it can reduce pitching in heavy seas and has also been provided in tankers, bulk carriers and modern cargo liners to increase speed when in ballast.
Hydrodynamic study of the influence of bow and stern appendages in the performance of the vessel OPV 93
Published in C. Guedes Soares, T.A. Santos, Progress in Maritime Technology and Engineering, 2018
B. Verma, D. Fuentes, L. Leal, F. Zarate
The main objective of the bulbous bow is to reduce bow wave height caused by local pressure disturbance formed in the bow of the vessel during its motion as indicated by Figure 4. As can be seen that the height of the bow wave is substantially reduced, which reduces the hull drag associated with the bow wave, thereby improving the fuel economy and increases ship range.
Numerical analysis of ship collisions accounting for bow and side deformation interaction
Published in C. Guedes Soares, Developments in the Collision and Grounding of Ships and Offshore Structures, 2019
Bin Liu, Gang Wang, Lin Chen, Xianting Liao, C. Guedes Soares
When the striking bow collides with the struck side of relatively larger ship at a right angle, the bulbous bow suffers severe deformation and absorbs considerable energy due to its much smaller relative rigidity. In this situation, it is unreasonable to consider the striking bow as a rigid bow.
A comparison of two ship performance models against full-scale measurements on a cargo ship on the Northern Sea Route
Published in Ships and Offshore Structures, 2021
Zhiyuan Li, Christopher Ryan, Luofeng Huang, Li Ding, Jonas W. Ringsberg, Giles Thomas
A general cargo ship is selected as the case study vessel in this work. The ship particulars and the propulsion system particulars are listed in Tables 3 and 4 respectively. The SPMs mentioned in the previous section are tested following these particulars. The Arctic voyages that will be presented in Section 4 are all simulated using this case study vessel. This vessel is of IA-class according to FSICR, which is roughly equivalent to IMO’s PC6 class. Full-scale measurements of ship performance have been collected on this vessel and measured data from Arctic voyages are assessed with the simulation results, which will be presented in Section 5. It is noteworthy that this vessel has a straight bow instead of a conventional bulbous bow. Arctic full-scale measurements on such a cargo ship of a lower ice-class are reported for this first time in this publication.
An overview of wire arc additive manufacturing (WAAM) in shipbuilding industry
Published in Ships and Offshore Structures, 2021
The last suggested implementation of WAAM in shipbuilding is the manufacturing of bulbous bow. In modern ships, bulbous bows have become an indispensable part of the new generation ships. The design of the bulbous bow is needed during the preliminary design level in order to predict the speed and power. In principle, the bulbous bow generates the wave system that interferes with the wave system generated by the ship. Due to difficulties and high cost during the manufacturing, the designers follow some guidelines namely, avoiding double curvature plates and decreasing the curvature of the free-form curved plates, decomposing them into smaller ones. These limitations reduce the design flexibility of the bulbous bow. Therefore, the production of the bulbous bow as one part by WAAM may offer the use of an optimised geometry.
Hydrodynamic optimisation of a multi-purpose wind offshore supply vessel
Published in Ship Technology Research, 2020
Yanxin Feng, Ould el Moctar, Thomas E. Schellin
The basic curves can be parametrised using the F-splines, which are controlled by many form parameters. The advantage of using F-splines to generate the basic curves is that it can reduce the complexity arising from the parameter input sets, while increasing flexibility and improving shape quality. Here, we fully parameterised the forebody hull form and the bulbous bow of the subject supply vessel for the shape variation, while we left the aftbody hull form unchanged. The parametric model of hull form included global parameters (e.g., ship dimensions) and basic curves to idealise the longitudinal distribution of the geometric parameters (e.g., position, tangent, curvature, and area). Table 2 describes the basic curves of the hull form. Figure 3(a ,b) show the longitudinal curves of the forebody hull and the basic curves of bulbous bow, respectively. Figure 4 shows the original and the initial full forms and Figure 5 their body plans. Recall that we modified only the forbody part of the ship hull to investigate the improvement of the ship's resistance performance.