The sound field properties for non-cavitating marine propellers are studied using FW-H (Ffowcs William-Hawkings) acoustic analogy and BEM (Boundary Element Method) approach. For the first time, the FW-H formula to calculate acoustic pressure generated by the propeller wake sheet is proposed. The corresponding sound signal can be dominant up to several kilometres. Secondly, non-physical fictitious volume flux is observed when the permeable FW-H approach is used together with BEM. The reason is explained and a virtual source correction method is proposed to solve this problem. Furthermore, analytical analyse show that the second thickness term and the first two loading terms in Farassat 1A formula are important, and the others are negligible. The numerical studies show that the permeable FW-H approach produces underestimation when compared to the direct FW-H method, and the underestimation is severer for larger permeable surface and higher frequency. It is also found that the first loading term in Farassat 1A formula is the dominant source term in the direct FW-H method, while the first thickness term is dominant when the permeable FW-H approach is used.