Design of Dihedral Bows: A New Type of Developable Added Bulbous Bows—Experimental Results

Abstract

This paper presents the design and the experimental results of a new type of developable added bulbous bow that has been designated as a dihedral bow. This type of bow is based on polyhedral bows that are used in small vessels, whose origin is traced to the 1990s. The bow is designed with a set of developable surfaces that are designed following previous methodology on surface design that considers material properties and can contain boundary curves. Two dihedral bow designs and their towing tank tests are presented in this work. A displacement and a semi-displacement hull were tested in two different loading conditions and for different Froude numbers. An important reduction of the effective power (PE) of the ships with the dihedral bow was observed during the experiments. There is a reduction of about 20% for the displacement hull and about 16% for the semi-displacement. The design methodology for the dihedral bows is presented in this paper together with experimental results on power, sink and trim. Dihedral bows are a good option for efficient small ship design, as well as larger ships.

Keywords

• developable surfaces in ship design
• bulbous bow design
• towing tank experiments
• effective power reduction