Ship collisions are marine accidents that may have catastrophic outcome. Commonly, an orthogonal collision with a fully laden oil tanker at its amidships area is considered. Much less attention is given to collisions affecting struck ship fore and aft part, the effect of struck ship speed, collisions with other floating objects etc. In most of these cases the effect of surrounded water becomes pronounced. Present work aims to investigate the consequences of applying two different realistic ship collision modelling techniques involving fluid-structure interaction (FSI) analysis in LS-Dyna: arbitrary Lagrangian–Eulerian (ALE) technique and rigid body MCOL coupling, using LPG ship and a ferry collision scenario as a study case. First, calibration of ALE parameters was made and then ship collision simulation is performed by ALE technique. In parallel, struck ship hydrodynamic parameters were calculated and collision simulation is performed again using MCOL/LS-Dyna coupling. Then, results are compared and discussed.

The aim of this paper is to present a methodology for the assessment of the structural reliability of an oil tanker damaged in a hypothetical collision accident in the Adriatic Sea. Monte Carlo simulation is employed to generate random damage scenarios. Assumption of the damage size is based on the numerical simulation of the ship–ship collision. Residual ultimate strength and still-water bending moment distribution are determined based on the size and location of the damage. Structural reliability analysis is employed to determine the safety index with respect to the ultimate hull-girder failure. Histograms of safety indices are thus obtained, representing new measures for the performance assessment of the damaged ship. If extended to more severe design wave environments and collision scenarios, the presented methodology may be used for general reliability-based comparison of different alternative designs of marine structures with respect to the accidental failure modes or for improvement of ship structural design rules.

The consequence of the near realistic modelling of collision damage shape on the post-accidental ultimate hull girder strength of double-hull oil tanker is investigated. For known striking ship’s geometry of the bulbous bow, damaged elements are removed from the finite element model of the midship section of the struck ship. Progressive finite element collapse analysis is then performed to determine residual strength index (RSI) of damaged ship. The analysis is performed for set of 50 collision scenarios, obtained from the historical ship collision database. In addition, probabilistic analysis of RSI is performed by approximating damage shape as ‘rectangular box’, based on IMO and GOLADS project. Structural reliability analysis is then employed to assess the consequences of various modelling assumptions used in RSI computations. Results of the analysis show that near realistic modelling of damage shape results in much lower failure probability of damaged ship compared to the ‘rectangular box’ models.

Ship collisions are rare events that may have a significant impact on the safety of people, ships, and other marine structures, as well as on the environment. Because of this, they are extensively studied but events that just precede collision are often overlooked. To rationally assess collision risks and consequences, a ship’s trajectory, and consequently the velocity and collision angle, should be known. One way to achieve this is through accurate modelling of ship manoeuvrability in collision analysis using non-linear FEM (NFEM). The Abkowitz manoeuvring model is implemented in the LS-Dyna software code and is therefore coupled with FEM calculations. Hydrodynamic forces are calculated in each time step of the LS-Dyna calculation and added to the FE model continuously through calculation. The accuracy of the calculations depends on the choice of and values of hydrodynamic derivatives from the Abkowitz model. Abkowitz’s model derives hydrodynamic forces in the Taylor expansion series to provide hydrodynamic derivatives. The application of the procedure is sensitive on higher-order Taylor series members. This article reviews different sets of hydrodynamic derivatives available for the KVLCC2 ship. Each of them is incorporated into the LS-Dyna NFEM solver by a user-made Fortran subroutine, with standard Zigzag and turning manoeuvres simulated and results compared with the experimental tests. As a result, the optimal selection of hydrodynamic derivatives is determined, laying a foundation for assessing the risk of ship collision due to different ship manoeuvres prior to the collision itself.

Synthetic fibre mooring lines are used as an alternative to traditional steel wire ropes due to their higher strength to weight ratio. Benefits are also found in relative ease of handling, and therefore the marine industry has largely accepted this type of mooring line. By rules and regulations, the design of mooring lines should be based on a coupled dynamic analysis of a particular mooring system and moored vessel. This approach incorporates damping and inertial forces (i.e., hydrodynamic reactions) acting directly on the mooring lines due to their motion through the seawater. On the basis of the outer diameter of the synthetic fibre rope, the Morison equation gives estimations of the mooring line hydrodynamic reactions. In comparison to the traditional steel wire ropes, the synthetic mooring lines usually have relatively larger elongations and consequently larger reductions of the outer diameter. Furthermore, the lower diameter certainly leads to reduced values of damping and added mass (of mooring lines) that should be considered in the coupled model. Therefore, the aim of this study was to develop a new numerical model that includes diameter changes and axial deformations when estimating the hydrodynamic reactions. The development of the model is carried out with a nonlinear finite element method for mooring lines with the assumption of large three-dimensional motions. The obtained results show the effectiveness of the newly developed model as a more accurate approach in calculation of hydrodynamic reactions.

Reducing CO₂ emissions from ships in unprofitable coastline transport using electricity and hydrogen has potential for island development to improve transport and protect biodiversity and nature. New technologies are a challenge for shipping companies and their introduction should be accompanied by a system of state aid for alternative energy sources. The energy requirements of an electric ferry for a route of up to 6 km were considered, as well as the amount of hydrogen needed to generate the electricity required to charge the ferry batteries to enable a state aid scheme. For a daily ferry operation, a specific fuel consumption of 60.6 g/kWh of liquid hydrogen is required in the system fuel cell with a total of 342.69 kg of hydrogen. Compared to marine diesel, the use of electric ferries leads to a reduction of CO₂ emissions by up to 90%, including significantly lower NOx, Sox, and particulate matter (PM) emissions, and operating costs by up to 80%.