Citation: Rahmaji, T.; Prabowo, A.R.; Tuswan, T.; Muttaqie, T.; Muhayat, N.; Baek, S.-J. Design of Fast Patrol Boat for Improving Resistance, Stability, and Seakeeping Performance. Designs 2022, 6, 105. https://doi.org/10.3390/ designs6060105 Academic Editor: José António Correia Received: 5 September 2022 Accepted: 27 October 2022 Published: 1 November 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Article Design of Fast Patrol Boat for Improving Resistance, Stability, and Seakeeping Performance Tri Rahmaji 1 , Aditya Rio Prabowo 1, * , Tuswan Tuswan 2 , Teguh Muttaqie 3 , Nurul Muhayat 1 and Seung-Jun Baek 4 1 Department of Mechanical Engineering, Universitas Sebelas Maret, Surakarta 57126, Indonesia 2 Department of Naval Architecture, Universitas Diponegoro, Semarang 50275, Indonesia 3 Research Center for Hydrodynamics Technology, National Research and Innovation Agency (BRIN), Surabaya 60112, Indonesia 4 Department of Naval Architecture and Marine Systems Engineering, Pukyong National University, Busan 48513, Korea * Correspondence: aditya@ft.uns.ac.id Abstract: Indonesia is the largest archipelagic country and has the potential to become the world’s maritime axis. Two-thirds of Indonesia’s territory is ocean, with a total coastline of 54,716 km. Therefore, Indonesia must have solid systems and tools to overcome the various threats in the maritime sector. One of the technologies that can be developed to protect Indonesia’s naval territory is fast patrol boats. Indonesia requires efficient patrol boats that can optimally monitor the large Indonesian sea area and various potential threats in the maritime sector. Thus, research on the hydrodynamic criteria for the hull design of patrol boats is fundamental. In this study, we aimed to evaluate the design method based on hydrodynamic characteristics to obtain the primary dimensions and shape of the ship’s hull. We designed and analysed 11 ship models in terms of the following criteria: the resistance, stability, and seakeeping performance. The 11 models included five reference models of patrol boats with varying dimensions and block coefficients between 0.42 and 0.53, three ship models with the regression method with the exact dimensions and block coefficients between 0.45 and 0.46, and three ship models with the scale method with the exact measurements and block coefficients between 0.43 and 0.45. According to the analysis results, the regression method had better total hydrodynamic criteria and greater similarity to the reference vessel. With a shorter processing time, the regression method was more efficient than the scaling method and reference ship. Keywords: archipelagic country; patrol boat; design method; hydrodynamic 1. Introduction Indonesia is an archipelagic country with 17,508 islands that are spread over a distance of 5000 km [1]. Two-thirds of Indonesia’s territory is ocean, with a total coastline of 54,716 km. With its strategic location between two continents (the Asian continent and Australian continent) and two oceans (the Indian Ocean and Pacific Ocean), Indonesia has the potential to become the world’s maritime axis [2]. As an archipelagic country that has become the world’s shipping traffic lane, Indonesia is responsible for safety and security in the territorial sea, which is within its jurisdiction [3]. The increasingly dynamic global politics poses a threat to the maritime sector in terms of illegal fishing, illegal trade routes, and global terrorism. Protecting the sea border is a top priority for the Indonesian government. Indonesia must have a strong fleet to monitor and safeguard its territorial sovereignty from various threats. In response to this, the government of Indonesia has created an integrated fleet system with a focus on strengthening submarines, frigates, and patrols boats with minimum essential force (MEF) (2024). Fast patrol boats are part of the fleet that used to monitor Indonesia’s border areas. These ships are relatively small but have a high enough speed that they can increase the time Designs 2022, 6, 105. https://doi.org/10.3390/designs6060105 https://www.mdpi.com/journal/designs