Effects of the application of a stern foil on ship resistance: A case study of an Orela crew boat

Abstract

The effects of the application of a stern hydrofoil on ship resistance were studied numerically using computational fluid dynamics (CFD) and were verified using data from model tests. A 40 m planing-hull Orela crew boat, with target top speed of 28 knots (Froude number, Fr = 0.73), was considered. The stern foil (NACA 64(1)212) was installed with the leading edge positioned precisely below the transom with angle of attack of 2 degrees at elevation 0.853 T below the water surface (where T is the boat's draft). At relatively low speed (Fr < 0.45) the application of a stern foil results in an increase in ship resistance (of up to 13.9%), while at relatively high speed (Fr > 0.55) it results in a decrease in ship resistance (of up to 10.0%). As the Froude number increases, the resistance coefficient (CT) first increases, reaches a maximum value, and then decreases. Its maximum value occurs at Fr ≈ 0.5, which is consistent with the prediction of a resistance barrier at approximately this Froude number.