Further investigation into the hydrodynamic performance of the AXE Bow Concept

In an earlier paper the first two authors presented the results, which they obtained from a desk study on the influence of a rather pronounced bow shape modification on the seakeeping behavior of a fast patrol boat. This bow shape modification (the so called AXE bow) became possible after applying the Enlarged Ship Concept on a 26 meter length over all patrol boat and was first introduced by the first two authors in 1995. In this paper the results of extensive towing tank measurements with the AXE Bow model and the same model with a conventional bow are presented and compared. These model tests have been carried out in the Delft Shiphydromechanics Laboratory. Tests have been carried out in calm water to measure the calm water resistance, the sinkage and the trim of the designs. In addition ship motion measurements have been carried out, primarily in head waves conditions, which were aimed at a validation of the computational results as presented in the previous paper, which were obtained from calculations with the nonlinear code “FASTSHIP”. In addition a number of numerical simulations have been carried out with these two designs in moderate to high stern quartering sea states using the nonlinear code “FREDYN” of MARIN. Aim of these calculations was to compare both designs with respect to their motions in following waves (not available during the tests) and on their possible sensitivity for the broaching phenomenon and/or heavy rolling in those conditions. The results of these tests and calculations and the comparisons between the two designs are presented and discussed in this report.