Design of Havfarm 1

Abstract

Very Large Floating Structures are an important part of urban floating development and offshore food production. To increase the production of salmon in Norway the offshore fish farm Havfarm 1 is built. The Vessel is 385 m long and has capacity for 10,000 ton salmon. To accommodate the fish nets the structure has an open bottom, which limits the torsional stiffness of the structure. This increases the natural periods to be of the same order of magnitude as typical wave periods in moderate sea states, introducing the need to capture the dynamics with coinciding natural periods and excitation periods. A new method is developed allowing for accurate estimation of fatigue utilization around the natural periods by including the effects of hydroelasticity. Furthermore, the use of well-known structural details from the oil and gas industry is incorporated in the steel-design. Together, this led to a robust steel-design that was verified and approved by DNV-GL and built for operation in Norway in 2020. The design of Havfarm 1 shows that structural dynamics around the natural period can be captured and practically used in the structural analysis. The building of Havfarm 1 provides a benchmark and opportunity for the development of other VLFS.