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Uniform symmetric bodies can be observed floating asymmetrically under certain circumstances. Previous explanations of this are mostly abstract and lack experimental verification, making their understanding and application difficult. This article presents in detail alternative insights into the floating equilibria of uniform prisms and parabolic cylinders. The intrinsic characteristics of the equilibrium curves are investigated, and several equilibria different from those in the literature are found. The inflection points in the equilibrium curves are analyzed quantitatively due to their significance for floating states. Furthermore, experiments have been conducted for the square prism which validate the derived equilibrium curve, and provide a practical impression of the asymmetric floating phenomenon of symmetric bodies. These results have the potential to be applied in naval and ocean engineering, such as in the design of vessels and floating offshore structures.

A variety of floating structures at sea play a vital role in the exploitation and utilization of marine resources. The study about interactions between waves and structures is necessary for the impact of the harsh marine environment on the motion and service life of structures. Currently, most studies about the seakeeping of structures are based on simplified regular waves. Because the regular waves do not truly restore the actual wave conditions at sea, the simulation of irregular waves has great practical importance to the study of interactions between waves and structures. Based on the potential flow theory and high-order boundary element method (HOBEM), a Fortran code is developed in this paper and named as SWBI (Solver for Wave–Body Interactions). This program consists of the following two parts: a time–domain numerical model about interactions between waves and 3D structures is based on weakly nonlinear method, and a numerical model about simulation of the nonlinear regular waves, the long-crested irregular waves, and the short-crested irregular waves. This Fortran code is used to simulate the motion of Floating Production Storage and Offloading (FPSO) under three different ocean wave spectra (including ITTC two-parameters spectrum, JONSWAP spectrum and the most likely spectral form of Ochi-Hubble) and found that: To a certain extent, the difference in the motion of FPSO under different wave spectra have a connection with different type of wave, sea conditions and incident angle. The difference in roll of FPSO is quite significant in short-crested irregular waves. The range of FPOS's roll under the JONSWAP spectrum is the largest when the incident angle is 30°, and range of FPOS's roll under the most likely spectral form of Ochi-Hubble is the largest when the incident angle is 90°. [ABSTRACT FROM AUTHOR]