S Samuel - Department of Naval Architecture, Faculty of Engineering, University of Diponegoro, Semarang, ۵۰۲۷۵, Indonesia
Untung Budiarto - Department of Naval Architecture, Faculty of Engineering, University of Diponegoro, Semarang, ۵۰۲۷۵, Indonesia
Akbar Wijaya - Department of Naval Architecture, Faculty of Engineering, University of Diponegoro, Semarang, ۵۰۲۷۵, Indonesia
Serliana Yulianti - Department of Naval Architecture, Faculty of Engineering, University of Diponegoro, Semarang, ۵۰۲۷۵, Indonesia
Kiryanto Kiryanto - Department of Naval Architecture, Faculty of Engineering, University of Diponegoro, Semarang, ۵۰۲۷۵, Indonesia
Muhammad Iqbal - Department of Naval Architecture, Ocean, and Marine Engineer University of Strathclyde, Glasgow, UK.

Drag is one of the main factors in improving fuel efficiency. Various study in regards to improving drag performance of a planing hull amongst them is a stern flap. The main parameters to design stern flap are Trailing-Edge Down (TED), span length or flap width, and chord length. Stern flap works by changing pressure distribution over the ship's bottom and creating a lift force on the stern transom part. This study aims to analyze the behavior of stern flaps in variations of span length and trailing edge down angle towards drag performance of Fridsma hull form. To be able to understand stern flap effectivity. Finite Volume Method (FVM) and RANS (Reynolds-Averaged Navier - Stokes) are used to predict the hull resistance during simulations. Obtained results show that shear drag is very sensitive towards the total drag value, proving that shear drag valued at least ۶۰% of the total drag in each planing hull multi-phase characteristics phase. Stern flap with ۵۸% of hull breadth span length installed in ۰° is considered the most optimal, reducing ۱۰,۲% of total drag, followed by ۱۸% displacement reduction. In conclusion, the stern flap effectively improves the Fridsma hull’s total drag and its components on ۰.۸۹ < FR < ۱.۸۹.

Drag, Stern Flap, Planing hull