Abstract

The effects of stern flaps in the hydrodynamic performance of a semi-displacement hull were evaluated by systematic testing of scaled models in a towing tank. Chord length, span and flap angle were chosen as the main variable parameters to obtain six different stern flap configurations. The semi-displacement hull in conjunction with each stern flap was tested in order to assess the influence of each flap in resistance and running trim. The bare hull, i.e. without stern flap, was also tested to provide a suitable base for flap performance comparison. Main characteristics of the stern flaps were chosen according to existent recommendations provided in the relevant technical literature. The results showed good agreement with these recommendations; however, it was found that larger values of chord lengths and negative flap angles could possibly have a better performance on this craft.