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Most sports like surfing are highly developed. It is necessary to tease the last percentages out of the competitors and equipment&#8212;in the case of surfing the surfboard-fin-system&#8212;to win competitions or championships. In this computational investigation, a parameter study of the positioning of the two rear fins within a 4-fin configuration with fixed front fins on a surfboard is executed to find appropriate fin positions for specific surf situations. Four different inflow velocities are investigated. The RANS and URANS models combined with the SST <inline-formula> <math display="inline"> <semantics> <mrow> <mi>k</mi> <mo>&#8722;</mo> <mi>&#969;</mi> </mrow> </semantics> </math> </inline-formula> turbulence model, which is available within the computational fluid dynamics (CFD) package STAR-CCM+, are used to simulate the flow field around the fins for angles of attack (AoA) between 0&#176; and 45&#176;. The simulation results show that shifting the rear fins toward the longitudinal axis of the surfboard lowers the maximum lift. Surfboards with 4-fin configurations are slower in nearly the whole range of AoA due to a higher drag force but produce a higher lift force compared to the 3-fin configuration. The lift and drag forces increase significantly with increasing inflow velocity. This study shows a significant influence of the rear fin positioning and the inflow velocity on lift and drag performance characteristics.