Preliminary design of a search and rescue vessel

Abstract

The challenge for any naval architect when conducting a preliminary design for any type of seafaring vessel is always similar: ensure that the client’s requirements are adhered to and the vessel is designed as efficiently as possible, ensuring the safety of all passengers and coherence with relevant rules and regulations. In the case for ‘Search and Rescue’ (SAR) vessels, the technology used for the design stage has vastly improved, with a better understanding of pertinent theories being achieved. Nowadays, vessel design is performed using one major tool: the design spiral. The first step in the design spiral was to create a conceptual design, by first conducting a thorough market survey and establishing design requirements, culminating in the design statement, showing the main parameters to be used for the conceptual design, such as an overall length of 20.0 m. The hull was generated using commercial software and mass estimates were conducted using an iterative procedure, until the final mass displacement of 41,443 kg was calculated for the vessel. A detailed general arrangement and lines plan were drawn up to provide the client with a clear understanding of the vessel to be designed, finalising the conceptual design. The next step in the design spiral was to analyse various key parameters, including resistance and power, equilibrium and stability, and sea keeping and motion sickness analyses. Using a combination of analytical equations and software, the estimated total resistance at the maximum design speed of 35 kn, considering sea state and appendages, was found to be 68.59 kN, resulting in an installed power of 2940.74 kW. At this stage the choice of engine had to be re-considered, resulting in a slight change in the overall displacement of the vessel. An equilibrium analysis was conducted to ensure proper hydrostatic limits, followed by a stability analysis performed at three realistic loadcases, each analysing various criteria outlined in the rules and regulations together with the self-righting capability of the vessel. Finally, sea keeping and motion sickness analyses were carried out, whereby operational limits for the vessel and passengers and crew were established, considering various sea states, headings and speeds. Concluding with a 3D rendered image of the finalised design together with a 3D printed physical model. All results were aligned with the client expectations, regulatory framework and all the project objectives, thus finalising the preliminary design.