Influence of propeller shaft angles on the speed performance of composite fishing boats

Abstract The propeller shaft inclination angle is one of the critical parameters influencing the speed of a fishing boat. This study assesses how the propeller shaft inclination angle impacts the speed of composite fishing boats through experimental and numerical analyses. The model used for testing is a scaled-down version of a 24.0 m × 6.5 m × 3.5 m fishing boat, constructed at a 1:12 scale using composite materials (polyester resin and fiberglass). The model allows for the propeller shaft angle adjustment from 0° to 15°. The model was tested at the design speed of 2.9 knots to measure the vessel’s speed corresponding to various inclination angles. Additional tests were conducted at lower (2.31 knots) and higher (3.46 knots) speeds to validate the results. The model was also simulated using computational fluid dynamics (CFD) software to compare and assess the reliability of the experimental results. Subsequently, the CFD software was employed to simulate the actual vessel and evaluate its performance. The results of the experiments and simulations demonstrate significant variations in vessel speed as the inclination angle increases from 0° to 15°. The maximum speed was achieved when the propeller shaft inclination angle ranged between 6° and 7° (reaching 3.05 knots). The vessel speed decreased substantially when the inclination angle increased from 9° to 15°. The speed variation patterns for the 2.31 knot and 2.9 knot cases were similar, whereas the 3.46 knot case exhibited notable differences. The optimal propeller shaft inclination angle range for achieving high speeds for the studied vessel lies between 3° and 8°.