International Shipbuilding Progress - Volume 66, issue 2

Authors: Choi, Bongjun | Wellens, Peter R. | Huijsmans, Rene H.M.

Article Type: Research Article

Abstract: The linear relationship between the pressure and the relative wave elevation on the hull surface is a prominent factor to be reconsidered in relation to the uncertainty of the added resistance. An evaluation method is proposed to access the nonlinear relationship between the hull pressure and the relative wave elevation, which has a decisive influence on the added resistance evaluation. This method is used to experimentally investigate the effect of bow-wave breaking of the fast displacement ship in waves. The results show that the nonlinearity between relative wave elevation and hull surface pressure due to the plunging breaking of a …bow wave is intuitively detected using the proposed analytical tool. The effect of bow-wave breaking is deduced by comparing the integral of the local pressure. This study provides important insight into the nonlinear relationship between relative wave elevation and added resistance. In addition, the findings provide a better understanding of the process of plunging breaking of bow waves. The procedure of plunging type of bow-wave breaking is defined in three stages considering the relationship between pressure and wave height: bow-wave developing stage, pile-up and breaking stage, and bow-wave absent stage. Show more

Keywords: Bow-wave, breaking, added resistance, nonlinearity, fast ship

DOI: 10.3233/ISP-180242

Citation: International Shipbuilding Progress, vol. 66, no. 2, pp. 111-143, 2019

Authors: Mauro, Francesco | Nabergoj, Radoslav

Article Type: Research Article

Abstract: During the design process of an offshore vessel, the DP system is not representing one of the primary constraints for the general arrangement of the vessel. Usually the location of the thruster devices is driven by the internal spaces available, i.e. the thrusters position is not optimised to reach the maximum capability. This is also true for a conversion of an existing vessel. Nowadays almost all offshore vessels require the installation of a DP system on board, means that it could be worthy to study more in detail the arrangement of the thrusters in such a way to maximise the …capability of the vessel to keep position with a determined amount of power installed on board. In the present work a procedure aimed to find an optimal thruster location on the hull during early design stage will be presented. Using a quasi-static approach for DP capability evaluation, an optimisation procedure based on genetic algorithm has been developed, considering the constraints given by the vessel geometry. The discussion is supported by a test case on a reference vessel, were the original layout is compared with two possible optimised configurations. Show more

Keywords: Dynamic positioning, thrusters positions, optimisation, offshore vessels

DOI: 10.3233/ISP-180248

Citation: International Shipbuilding Progress, vol. 66, no. 2, pp. 145-162, 2019

Authors: Bertagna, Serena | Laurini, Erik | Marinò, Alberto | Nasso, Carlo | Pricl, Sabrina | Bucci, Vittorio

Article Type: Research Article

Abstract: Metallic alloys play the leading role in marine engine construction. Yet, under the compelling goal of reducing cost and weights, this industrial sector is in constant need of new, high-performance materials for the production of marine engine non-structural components. In this respect, nano-engineered thermoplastic polymers are ideal alternatives, allowing for additional benefits (e.g., simplified maintenance and inspection operations). The use of these materials in marine engine design requires computer multiscale simulations to tailor-fit their molecular structure in order to achieve the expected performances required by specific, advanced functions. Importantly, replacing metal alloys with plastic-based materials also contributes to environmental sustainability, …in terms of both component production process and recyclability. The introduction of non-structural plastic components in marine engines constitutes a major innovation in the field; thus, a specific rule framework must be still defined. Under this perspective, starting from the analysis of the rule framework currently used for metallic alloys, in this paper a certification procedure is proposed and applied to a case study: a four-stroke marine engine plastic cylinder head cover for which the mechanical properties of the new material have been predicted and verified trough multiscale simulations carried out on the relevant model. Show more

Keywords: Marine engines, material design, reinforced polymers, composites, plastic components

DOI: 10.3233/ISP-180253

Citation: International Shipbuilding Progress, vol. 66, no. 2, pp. 163-180, 2019

Authors: Boveri, Alessandro | Di Mare, Giovanni Alberto | Rattazzi, Diego | Gualeni, Paola | Magistri, Loredana | Silvestro, Federico

Article Type: Research Article

Abstract: The International Maritime Organization has developed regulations intended to increase the ship’s efficiency both in design phase, through the introduction of an Energy Efficiency Design Index (EEDI), either in management phase, adopting the Ship Energy Efficiency Management Plan (SEEMP). Several approaches and technologies adopted in land-based engineering in the field of energy efficiency can also be advantageous for marine applications. This is the case of the Distributed Energy Resources (DER) solution applied in land-based microgrids, which increases both the system’s efficiency and reliability. In this work, a distributed energy system will be considered for a 140000+ GRT cruise ship, installed …for a superior performance in terms of safety and energy efficiency. Number, typology, size and integration on board of the generation units will be defined in relation with aspects of zonal independence, electrical load, weights, volumes, fuel tanks, supply systems, auxiliaries, with the minimum possible impact on commercially valuable space and a special focus on the fuel cells technology. The critical issues in relation with the present safety rules and the whole ship design process will be addressed as a fundamental aspect. Show more

Keywords: Cruise ship, innovative energy generation, shipboard power systems, distributed energy resources, LNG, fuel cells, microgas turbines

DOI: 10.3233/ISP-180259

Citation: International Shipbuilding Progress, vol. 66, no. 2, pp. 181-199, 2019