LAUSR

Abstract Increasing water demand in remote coastal areas in Egypt has shifted attention to the role of floating desalination plants to alleviate water shortages. A novel mobile floating desalination plant is proposed for Ras Ghareb city in Egypt. The compatibility between floater natural periods and the energy excitation range of waves in deployment area can lead to resonance responses. Therefore, understanding the motions behaviour among waves of such floaters at a particular location is important for its safety, performance and operation. The goal of the present study is to investigate the suitability of proposed concept for Egyptian environment conditions by characterising the behaviour of the plant motion responses during its entire deployment conditions. Based on full scale design of the proposed plant, experimental study over a range of wave heights and frequencies was performed in the present study using a 1:100 scale model test. In order to identify the plant natural frequency and damping ratio, free decay and swinging tests were performed for different load conditions. Different wave heights were tested during the experiments in order to investigate the effect of wave height on the heave and pitch responses at plant natural frequencies. The experimental test results were compared with numerical results from frequency domain program HydroD implemented in Sesam DNV GL software package. Results show that heave and pitch motion responses give the closest agreement between the measurements and numerical predictions over the whole range of wave periods except the peak spike. The proposed cylindrical FDP is compared against a conventional ship FPSO concept widely used for offshore freshwater production and it was concluded that new cylindrical FDP shows better motion responses compared to conventional ship FPSO concept in same wave bands in Egypt.