The main transport channel of the global economy is represented by shipping. Engineers and hull designers are more preoccupied in ensuring fleet safety, the proper operation of the ships, and, more recently, compliance with International Maritime Organization (IMO) regulatory incentives. Considerable efforts have been devoted to in-depth understanding of the hydrodynamics mechanism and prediction of ship behavior in waves. Prediction of seakeeping performances with a certain degree of accuracy is a demanding task for naval architects and researchers. In this paper, a fully numerical approach of the seakeeping performance of a KRISO (Korea Research Institute of Ships and Ocean Engineering, Daejeon, South Korea) container ship (KCS) container vessel is presented. Several hydrodynamic methods have been employed in order to obtain accurate results of ship hydrodynamic response in regular waves. First, an in-house code DYN (Dynamic Ship Analysis, “Dunarea de Jos” University of Galati, Romania), based on linear strip theory (ST) was used. Then, a 3D fully nonlinear time-domain Boundary Element Method (BEM) was implemented, using the commercial code SHIPFLOW (FLOWTECH International AB, Gothenburg, Sweden). Finally, the commercial software NUMECA (NUMECA International, Brussels, Belgium) was used in order to solve the incompressible unsteady Reynolds-averaged Navier–Stokes equation (RANSE) flow at ship motions in head waves. The results obtained using these methods are represented and discussed, in order to establish a methodology for estimating the ship response in regular waves with accurate results and the sensitivity of hydrodynamical models.

The inland waterway cargo transport has extended over the decades, bringing up specific technical issues. From the hydrodynamics point of view, for the inland ships one of the most challenging issue is the effect of shallow water on the ship resistance. In the present study, there are developed numerical analyses for the viscous flow around a barge hull in the case of the shallow water fluid domain. The barge hull has prismatic shapes, in the cargo holds areas, with vertical sides, and geometric non-linear shapes more significant at the fore part. The hull shape CAD model is developed by Rhinoceros software. The numerical analyses are performed by CFD RANS-VOF method, with free surface and shallow-water, using the NUMECA / FineMarine software, having free sinkage and trim conditions. The shallow-water flow induces significant hydrodynamic non-linearities in compare to the deep-water flows. Several ship speeds and water depths are considered. We have focused on the identification of the ship's induced waves system and the resulting barge resistance. The conclusions of this study are stressing out the significant influence of the shallow-water conditions on the barge resistance, making possible to draw up practical technical information's for the barge hull design.

This study is focused on floating docks strength analysis by 3D finite element models, full extended over the dock length. The equilibrium position of the dock in the design equivalent quasi-static waves environment is obtained by own code, based on a non-linear iterative procedure. For the surrounding water and ballast tank water loads we have developed user procedures and functions implemented in the finite element programs. Also the still water conditions are analysed. The numerical study is developed for a small size floating dock, designed for multiple shipyards operation, with 60 m length and two constructive versions, having continuous and non-continuous side ballast tanks. As main operation cases of the small size floating dock are considered: light without docking ship, full ballast at maximum upper deck limit, three docking ship tests, with ship mass uniform, sagging and hogging type distributions, according to the shipbuilding classification societies rules. As assessment criteria, the 3D model yielding stress limit for global and local strength, buckling factor and maximum vertical deflection are considered. Also the freeboard criterion is considered. The results of the study are delivering the operation limits, in terms of design wave height, in order to ensure the strength safety rules requirements.

This paper presents the numerical and experimental analysis of the seakeeping performances of a survey vessel operating in the Caspian Sea. For the numerical analysis we have developed our own code, based on a linear hydro-dynamic strip theory formulation. The irregular waves are modelled by short-term power density spectra JONSWAP, for the spectral parameters significant wave height and peak period corresponding to the Caspian Sea scattering diagram. The experimental study is developed at the towing tank from Naval Architecture Faculty of Galati, using a semi-captive scaled model 1:16 of the survey vessel, made of fibre glass and wood, being recorded the heave, pitch, roll motions and wave elongation. The experimental tests are carried out for two speeds and several significant heading cases: head, follow and beam regular waves. This study delivers the prediction of the survey vessel seakeeping capabilities and the validation of the numerical response amplitude operators by experiment.

This study is developed for the strength analysis of a large floating dock, with length over all of 209.2 m, obtained from a conversion of an off-shore barge. The docking operations are evaluated by global and local strength criteria. The first operation scenario includes an entire translation process of a ship from the quay to the floating dock railway system, in a river shipyard location, including the main intermediate steps. A second set of operation scenarios include several trial docking cases, at full capacity, considering also the initial state without docking ship that is specific for transit condition between ports. The structural numerical analysis is developed on a very large 3D-FEM model, one sided, full extended over the length, involving an own iterative algorithm for the dock and head design wave equilibrium parameters computation and user functions for the quasi-static head wave pressure application on the external dock shell. The large floating dock has operations in sheltered and unsheltered environments and can be relocated on river and costal waterways, under specific wave's conditions, according to the shipbuilding classification societies design rules. The numerical results are making possible to evaluate the several operations of the large floating dock by strength criteria.

This paper is focused on an advanced method for ship structures fatigue assessment. The ships classification societies standard rules for fatigue analysis are based on simplified procedures, with wave induced loads obtained by linear oscillation analysis (low frequency, around 0.1 Hz), or equivalent statistical wave loads. In the case of large elastic ship structures, with hull length over 150 m, the global wave induced vibration response (high frequency, around 1 Hz) becomes significant. The developed integrated method for large ships fatigue assessment includes three interlinked analyses, as follows: the hot-spot stresses evaluation by 3D finite element models, wave induced loads by short term linear and non-linear hydroelastic dynamic analysis, ship service life and fatigue assessment by damage cumulative ratio method. As testing ship, it is considered a double hull LPG Liquefied Petroleum Gas carrier, with total length 239 m, for a set of structural details with stress hot-spots. Based on the non-linear hydroelastic wave loads, the integrated method of fatigue assessment becomes more accurate, predicting for the amidships structure 14 years of ship service life, instead of over 20 years according to the rules standard approach, so that the confidence on ship structure fatigue evaluation can be increased in the design process.