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All Journal Mekanika: Majalah Ilmiah Mekanika
Aldias Bahatmaka
Department of Mechanical Engineering, Universitas Negeri Semarang, Semarang, Indonesia

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Enhancing Ship Stability: A Comparative Analysis of Single and Double Chine Hull Configurations of Semi-Planning Hull at High Speed Andi Abdullah Ghyferi; Aldias Bahatmaka; Rizqi Fitri Naryanto; Lee Sang Won; Joung Hyung Cho
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 2 (2024): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i2.90734

Abstract

Ship stability could be considered one of the defining aspects of marine transport, as it directly influences the safety and performance of the ship. Past works have found hull geometry critical in the stability issue; however, the impact of various Chinese configurations under different operation scenarios is missing. This paper seeks to address this gap by studying the effects of Chinese single and double geometries on stability, primarily concerning trimming by stern angles in compliance with the High-Speed Craft (HSC) 2000. Annex 8: Monohull Intact Stability Criteria. Stability calculations using Maxsurf software were done concerning angles of the steady heel, the area under the righting levers (GZ) curve, maximum GZ, and initial transverse metacentric height (GMt). The study showed that both Chinese configurations conformed to the prescribed stability standards. Still, the double Chinese configuration showed better results in terms of stability at a 2-degree heel angle, with a GZ value of 1.692 and the highest GMt value in a steady state. Therefore, the research establishes enhanced stability benefits that the users stand to benefit from by adopting double chine configurations relative to single chine styles.
Numerical Analysis of Six Degrees of Freedom Motion Response of Trimaran Semi-Submersible Ship Musdika Bagas Satria Putrananda; Aldias Bahatmaka; Widya Aryadi; Berliana Ayarent Puteri; Christian Imanuel Hutagalung
Mekanika: Majalah Ilmiah Mekanika Vol 24, No 1 (2025): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v24i1.99057

Abstract

This study examines the motion response characteristics of a trimaran semi-submersible vessel, with a focus on its performance in tourism applications where passenger comfort is a primary concern. Using ANSYS AQWA simulation software, this analysis integrates diffraction and radiation theory with potential flow theory to evaluate the six degrees of freedom (surge, sway, heave, roll, pitch, and yaw) under various wave conditions, including different frequencies and directions based on the Joint North Sea Wave Project (JONSWAP) spectrum. Simulations were performed on waves with heading angles ranging from 0° to 180°. The simulation results were validated based on previous studies both experimentally and numerically. The results show that the sway peaks at 8 m/m for heading angles of 90°, while the surge reaches a maximum of 8 m/m at 0° and 180°. The heave motion resonates between 2.2 rad/s with a peak amplitude of 3 m/m at 90°. Pitch motion at heading angles of 0° reaches 40 °/m at 3.5-4 rad/s. Roll motion remained within acceptable limits (9 °/m), and yaw peaked at 13 °/m at 45° and 135°. These findings suggest that, although the trimaran exhibits stable performance in most motion responses, design improvements are necessary to mitigate excessive pitch motion and enhance passenger comfort in tourism applications.
Analytical Review of Numerical Analysis in Hydrodynamic Performance of the Ship: Effect to Hull-Form Modifications Aldias Bahatmaka; Deni Fajar Fitriyana; Samsudin Anis; Achmad Yanuar Maulana; Mamad Tamamadin; Sang Won Lee; Joung Hyoung Cho
Mekanika: Majalah Ilmiah Mekanika Vol 23, No 1 (2024): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v23i1.83635

Abstract

This review paper provides an overview of simulation-based hydrodynamic design optimization for ship hull forms. It also includes a numerical analysis aimed at accomplish early-stage simulation-based design in terms of hydrodynamic performance. A hydrodynamic module, a hull surface modeling module, and an optimization module are the primary components of this numerical analysis. The hydrodynamic module includes both simple design approaches and high-fidelity numeric tools; these integrated tools are used to evaluate hydrodynamic performances at different design stages. The hull surface modeling module offers a variety of techniques for ship hull surface representation and modification. It is also used to automatically create hull forms or change existing hull forms based on hydrodynamic performance and design constraints. The optimization module includes several optimization algorithms and surrogate models used to determine optimal designs in terms of hydrodynamic performance. Numerical findings indicate that the current tool is well suited for hull form design optimization at the early design stage because it can produce effective optimal designs within a short time.
Performance Analysis of the Fast Platform Supply Vessel with a Conventional V-Hull Shape with the Addition of a Chine and a Different Bow Using Computational Fluid Dynamics Method Fedrik Immanuel Rumapea; Aldias Bahatmaka; Banin Hamizan; Pramudya Rahardian; Umar Zaid Rantisi; Dias Fitria Kurniaputri
Mekanika: Majalah Ilmiah Mekanika Vol 25, No 1 (2026): MEKANIKA : Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v25i1.114601

Abstract

Indonesia is the largest country in Southeast Asia, consisting of more than 17,000 islands and a coastline of approximately 81,000 kilometers, with over half of its territory covered by water. To optimize this vast marine potential for public welfare, comprehensive data collection and mapping are essential. The oil and gas sector remains a key contributor to national revenue. For instance, Pertamina Hulu East Kalimantan (PHKT) exceeded its 2023 production target, achieving around 9,900 barrels of oil and 45 million cubic feet of gas per day. To support offshore operations, a Platform Supply Vessel (PSV) prototype named Bramantya was designed. This study analyzes the vessel using Computational Fluid Dynamics (CFD) to determine the optimal hull form for operational performance and fuel efficiency. Three hull variations were examined: a conventional hull, a hull with additional chines, and a wide-bow hull. The simulation was validated against previous experimental studies, showing consistent linear results with an average error of 4.25%. Simulations at Froude numbers 0.2–0.6 show that the wide downward-bowed hull reduces drag by 7.69% compared to the conventional hull, thereby improving fuel efficiency.
Co-Authors Achmad Yanuar Maulana Andi Abdullah Ghyferi Banin Hamizan Berliana Ayarent Puteri Christian Imanuel Hutagalung Deni Fajar Fitriyana Dias Fitria Kurniaputri Fedrik Immanuel Rumapea Joung Hyoung Cho Joung Hyung Cho Lee Sang Won Mamad Tamamadin Musdika Bagas Satria Putrananda Pramudya Rahardian Rizqi Fitri Naryanto Samsudin Anis Sang Won Lee Umar Zaid Rantisi Widya Aryadi