Ship designing is a complex process, as the ship itself is a complex, technical multi-level object which operates in the air/water boundary environment and is exposed to the action of many different external and internal factors resulting from the adopted technical solutions, type of operation, and environmental conditions. A traditional ship design process consists of a series of subsequent multistage iterations, which gradually increase the design identification level. The paper presents problems related to the design of a small untypical vessel with the aid of variant methodology making use of optimisation algorithms. The computer-aided design methodology has been developed which does not need permanent reference to already built real ships and empirical-statistical relations. Possibilities were indicated for integrating together early design stages, and parallel designing of hull shape and parameters.

Dynamic development in practically all fields of science and engineering has not passed over shipbuilding . In last years , engineers got to their use computer software which makes it possible to perform strength and hydrodynamic calculations as well as to visualize design projects in 3 D space [1][2][3][4]. At their disposal they have full spectrum of modern solutions associated with the use of advanced materials and technologies [5][6][7]. More and more attention is also paid to impact onto the natural environment [8,9]

The increase of seakeeping performance is of particular importance for car and passenger ferries, service ships in the gas and oil extraction industry and offshore wind power farm industry, as well as for special purpose ships (including military applications). In the water areas of the Baltic Sea, North Sea, and Mediterranean Sea, which are characterised by a short and steep wave, the hull shape has a substantial impact on the operational capacity and propulsion efficiency of the ship, as well as on comfort and safety of navigation. The article analyses selected aspects of seakeeping for four variants of a selected case study vessel, indicating practical limitations of the strip method. The analysed aspects included hull heaving and pitching, added resistance, Motion Thickness Indicator (MSI), and Subjective Magnitude (SM). Experimental tests were also performed in the towing tank. Their comparison with the numerical results has indicated high inaccuracy of the strip method. What is more, the simplified representation of hull shape used in the strip method makes it impossible to analyse the effect of hull shape changes on the predicted seakeeping characteristics. Especially for the case of head wave, neglecting highly non-linear phenomena, such as slamming or head wave breaking, in strip method-based computer simulations will significantly decrease the reliability of the obtained results. When using the strip method, the seakeeping analysis should be complemented with model tests in a towing tank, or by another more complex numerical analysis, such as CFD for instance.

Recently, there has been a significant development of ecological propulsion systems, which is in line with the general trend of environmentally friendly “green shipping”. The main aim is to build a safe, low-energy passenger ship with a highly efficient, emission-free propulsion system. This can be achieved in a variety of ways. The article presents the main problems encountered by designers and constructors already at the stage of designing the unit. The research conducted made it possible to create a design with an effective shape of the hull, with the prospect of an energy-efficient and safe propulsion system with good manoeuvrability. The scope of the research included towing tank tests, recalculation of the results in full-scale objects and a prediction of the energy demand of the propulsion system. The results obtained were compared to indicate power supply variants depending on the hull shape.

Usually, the concept of sufficient stability of a floating structure is connected with the capacity to keep a small heel angle despite the moment of heeling. The variable responsible for these characteristics is the initial metacentric height, which is the relation between the hydrostatic features of the pontoon and the mass properties of the entire object. This article answers the questions of how heavy the floating system should be, what the minimum acceptable draft is, and whether it is beneficial to use internal fixed ballast. To cover various technologies, a theoretical model of a cuboid float with average density representing different construction materials was analysed. The results indicate that the common practice of using heavy and deep floating systems is not always reasonable. In the case of floating buildings, which, unlike ships, can be exploited only under small heel angles, the shape and width of the submerged part of the object may influence the stability more than the weight or draft.