A comparative evaluation of hydrodynamic loads for a series of river chemical tankers converted into river – sea series

Abstract

One of the main problems to be taken into account is the availability of a reliable amount of information during the preliminary design stages. The present paper is focused on the analysis of the results obtained for several versions developed based on the initial version of a river chemical tanker, using a so-called jumboisation which is a technique in shipbuilding, consisting of enlarging a ship by adding an entire section to it. Moreover, the breadth of the prototype ship was also modified in order to evaluate the effects of all these modifications on the performances of the different variants, i.e., hydrostatics, ship hydrodynamic resistances, motorization solutions (main engine selection), EEDI (Energy Efficiency Design Index), etc. Originally, all the investigations have been carried out having as prototype a river chemical tanker of about 4600 dwt, obtaining 7 additional versions. The previous results allow us to develop a synthetic and coherent procedure which can provide a simplified manner to foresee which are the implications and impact of owner’s new requirements on the proposed performances of the new ship. Starting from the obtained results, the present paper is concentrated on the influences when the original ship is converted to a river-sea one, the main expected results being focused on the variation of the maximum values of the bending moments and shear forces acting on the ship girder. The extended calculations of ship resistance lead to higher values of the hydrodynamic forces and then, new main engines have to be selected having significant higher EEDI values. Consequently, the influences due to the modifications can be quantified and the impact as compared to the river ship case becomes possible. The evaluations have been carried out based on appropriate software, provided by Bureau Veritas.