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M. Uswah Pawara
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INDONESIA
Indonesian Journal of Maritime Technology or abbreviated (ISMATECH)
Published by Institut Teknologi Kalimantan
ISSN : -     EISSN : 3025518X     DOI : https://doi.org/10.35718/ismatech.v1i1
Core Subject : Engineering,
Civil Engineering, Building, Construction & Architecture Control & Systems Engineering Industrial & Manufacturing Engineering Mechanical Engineering Transportation
Focus and Scope Research titles encompassed by this journal include, but are not limited to: Naval Architecture: covering ship strength, Ship Hydrodynamics, Ship Construction, Ship Production Management, Wooden and FRP Ship Materials, Ship Design Innovation, Ship Vibration and Noise, Welding Technology, Fatigue, Sea Transportation, Computational Fluid Dynamic Modeling. Marine Engineering: encompassing Engine Performance, Renewable Fuels, Dual fuel system, Ship electricity, Ship Resistance, Ship piping systems, Ship reliability). Ocean engineering: Marine and Offshore Structures, Coastal Structures and Management, Port Structures and Management, Subsea Umbilicals, Risers and Flowlines (SURF), Ocean Renewable Energy, Marine Instrumentation, Marine Pollution. Mechanical engineering: addressing Tribology, Energy Studies, Engines and Turbines, Heat Transfer, Fluid Mechanics, Lubrication and Wear, Materials Science, Mechatronics, Refrigeration and air conditioning, Pressure analysis, Structural and mechanical design, Renewable energy, Structural mechanics, Thermodynamics, Materials processing, Vibration).
Arjuna Subject : Teknik (semua kategori) - Teknik Kelautan
Articles 62 Documents
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Development of Practical Wind-Assisted Ship Propulsion (WASP) Calculation for Fuel Consumption and Emission Reduction Isna Aulia Marifa; Dian Purnama Sari; Wiwin Sulistyawati
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8481967

Abstract

Integration of Wind-Assisted Ship Propulsion (WASP) serves as a strategic solution for the maritime industry to achieve Net Zero Emission by 2050. This research evaluated the interaction between sail design and route optimization for a 265 GT fishing vessel operating around Benoa, Bali to maximize fuel savings and emission reductions. Three hard sail profiles, arc-shaped, NACA 0012, and NACA 0015, were analyzed at operational speeds of 7 and 10 knots. An improved weather-routing framework based on the A* (A-star) algorithm* was developed, integrating weather forecasts, ship specifications, and force matrices to determine optimal navigational paths. Simulations conducted on routes around Benoa, Bali, demonstrated that the combination of aerodynamic wing sails and intelligent routing improved efficiency by 1.24% to 12.59%. The results confirmed that the synergy between WASP technology and precise pathfinding significantly reduced carbon footprints while enhancing the economic viability of shipping operations. These findings provide a scalable framework for sustainable maritime practices and for achieving global decarbonization targets.
Energy Efficiency Analysis of Main Cooling Pump System on Bulk Carrier Using VSD Fajri Ashfi Rayhan; Rashieka Alma
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8481980

Abstract

Improving energy efficiency in marine auxiliary systems has become increasingly important due to rising fuel consumption, stricter environmental regulations, and global green shipping initiatives. Conventional seawater cooling pumps on bulk carrier vessels generally operate at constant speed regardless of cooling demand, resulting in excessive energy consumption under partial-load conditions. Previous studies mainly focused on general Variable Speed Drive (VSD) applications, while limited research investigated the integrated performance of seawater cooling systems in bulk carriers, particularly the relationship between pump energy consumption, heat transfer performance, and operational efficiency. This study was conducted to evaluate the energy efficiency of the main cooling pump system on a bulk carrier vessel through the implementation of a Variable Speed Drive (VSD). The analysis was conducted using a thermodynamic simulation approach under steady-state conditions by applying pump affinity laws, heat transfer equations, and operational data from a MAN B&W S42MC marine diesel engine under various engine loads and seawater temperatures. The results show that VSD implementation reduced pump power consumption from approximately 26 kW to 2–10 kW under partial-load conditions, corresponding to improved pump efficiency, with a maximum efficiency of approximately 82% achieved near the Best Efficiency Point (BEP). The cooling system also maintained stable freshwater outlet temperatures around 36°C, indicating effective heat transfer performance, thermal stability, and improved cooling system energy efficiency. These findings confirm that VSD operation is highly effective under partial-load conditions and supports ship energy management systems to reduce fuel consumption and support sustainable green shipping practices.
Computational Fluid Dynamics Analysis of Breakwater Configurations for Enhanced Coastal Resilience in North Java Alif Nur Rochmad; Muhamad Rakif panguale; Muhamad Saiful Rahman Hamka; Septaviola Dini Utami
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8481960

Abstract

The North Java shoreline, much like coastlines elsewhere in the world, continues to suffer the cumulative effects of coastal erosion and storm surge, and breakwaters remain the principal line of defense against this incoming wave energy. A substantial number of these structures, however, are still sized and shaped using generic rules of thumb instead of being calibrated to site-specific wave conditions and seabed characteristics, and the body of published work that tests breakwater configurations against actual North Java conditions is still limited. The present study closes part of that gap by applying a Computational Fluid Dynamics (CFD) simulation framework to examine how breakwater geometry, porosity, and layout govern hydrodynamic behavior under representative wave loading. The free surface and the wave-structure interaction were resolved using the Volume of Fluid (VOF) approach, paired with a turbulence closure model appropriate for free-surface flow. Over the course of the simulated runs, the configurations under investigation brought wave height down from 1.25 m to roughly 0.45 m by t = 20 s. The seaward face experienced its largest dynamic pressure, 38.7 kPa, at t = 10 s, a moment that also coincided with the highest overtopping velocity of 3.42 m/s, even as flow inside the sheltered zone fell to only 0.22 m/s, a rate low enough to let sediment settle out. A subsequent sensitivity analysis showed that raising porosity by 10% together with a gentler slope gradient lowered the peak structural pressure by as much as 15%, yielding design guidance with practical relevance for North Java and comparable coastal settings
Comparative Analysis of Turbulence Models for Gawn Series Propeller using CFD Method Adhyve Priambodo Bhaskara; I Ketut Suastika; Mahendra Indiaryanto; Taufiq Arif Setyanto; Amalia Ika Wulandari; Dimas Fajar Prasetyo
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8481984

Abstract

The rapid advancement of computational technology has positioned Computational Fluid Dynamics (CFD) as an effective tool for predicting marine propeller hydrodynamic performance. This study applies a CFD-based numerical method using Reynolds-Averaged Navier–Stokes (RANS) equations to evaluate and compare the accuracy of three turbulence models, namely k–ε, k–ω, and k–ω SST for a Gawn Series marine propeller. CFD simulations were conducted by varying the advance coefficient (J). Verification of the results for each turbulence model was carried out through Grid Independence Study and Grid Convergence Index analysis. The CFD simulation results were then compared with experimental test data using the Root Mean Square Error (RMSE) method, with KT, 10KQ, and efficiency as evaluation parameters. The results demonstrate that the k–ω SST model provides the most consistent and accurate predictions across the entire operating range, with RMSE values of 1.24% for KT, 1.98% for 10KQ, and 1.88% for efficiency. Pressure‑contour visualization from the k–ω SST model shows the smoothest pressure distribution on the blade surface, while pathline visualization reveals the clearest, most consistent, and well‑balanced vortex structures downstream of the propeller, thereby providing a robust and reliable basis for selecting the most suitable turbulence model to improve the accuracy of CFD based marine propeller performance prediction.
Energy Efficiency and Battery Load Sharing Analysis of 26-m Electric Supply Boat Using MATLAB Atikah Rafiah; Surya Hariyanto
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8481994

Abstract

Load division between parallel battery units in dual-bus battery-electric vessels directly governs current imbalance and battery degradation, yet design-stage quantification remains limited. This study evaluates three battery sharing strategies for a 26-m electric supply boat with a 1,242 kWh LFP system under dual-bus DC architecture across five operating conditions using MATLAB with Coulomb counting and the Rint model. Power demand peaked at 644.31 kW at Transit 12 knots, where propulsion consumed 93.1% of the total energy budget. The optimal strategy achieved 0.0% load imbalance in four of five conditions against a static maximum of 8.2%, reducing the Joule loss index by 0.06% to 485,596 A2. The SOC-adaptive strategy worsened imbalance at Transit 12 knots from 1.5% to 7.8%, confirming that gradient-based shifting is structurally unsuitable for dual-bus battery-only vessels. Terminal voltage analysis identified the DC bus threshold as the binding operational constraint during full-load transit rather than the BMS protection limit, a finding with direct implications for load shedding procedure design in comparable all-electric workboats.
Resistance Analysis for the Application of Flowbow on DTMB 5415 Ship Arga Setya Andreardani; I Ketut Suastika; Baharuddin Ali; Taufiq Arif Setyanto; Mahendra Indiaryanto; Amalia Ika Wulandari; Anson Novendra Pradana
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8481997

Abstract

Flowbow is an innovation designed by Rasmussen to increase fuel efficiency by reducing wave making resistance of ship. It is claimed that Flowbow can reduce the resistance of displacement and semi-displacement hull type at Froude number (Fr) over 0.25 to 0.28. On a warship, resistance reduction can increase the patrolling endurance by reducing energy used to moving. This research comparing the hull of DTMB 5415 model, which is already using bulbous bow and the modified DTMB 5415 hull with the addition of Flowbow using CFD which is validated by EFD. The results show that the addition of a Flowbow reduces ship resistance at Fr greater than 0.249 and the resistance reduction increases as the ship speed increases. At the highest tested speed (Fr = 0.352), the total resistance reduction reaches 8.57%.
Technical Analysis of the Solar-Assisted Fish Cooling System for Fishing Boat Risal Amin; Gad Gunawan; Kharis Sugiarto; Happy Aprilia; Samsu Dlukha Nurcholik; Devy Setiorini Sa’adiyah
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8482000

Abstract

As an archipelagic country with a coastline of thousands of kilometers and enormous oceans with high diversity, Indonesia has very rich fishing resources from capture fisheries. But this maritime treasure is typically under-exploited, poorly managed and vulnerable to environmentally damaging activities. Indonesia can implement effective and environmentally friendly technical solutions to prevent marine pollution. For instance, the use of Solar Power equipment (SPS) in fishing vessels can meet the energy needs of the refrigeration equipment on board. The objective of this study is to investigate the viability of solar panel installation on fishing vessels and its effects on vessel stability. The results showed that the vessel's roof is fitted with eight solar panels, each with a capacity of 500 Wp, to create 14.92 kWh per day to power five refrigeration units. Stability analysis shows that the addition of rooftop solar panels, cooling boxes, and batteries in the fish hold is in compliance with IMO Standard A.749(18) Chapter 3, ensuring the safety of the system for practical application.
Structural Response and Optimization of a Tugboat Midship Section Under Varied Transverse Frame Spacing Using Finite Element Analysis Amalia Ika Wulandari; Alamsyah Alamsyah; Hariyono; Ryan Raruk; Husein Syahab; Muhammad Anjas Syam; Suardi Suardi; Dimas Fajar Prasetyo
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8482002

Abstract

Transverse framing systems serve as a critical structural backbone for marine vessels, governing localized stiffness and cross-sectional hull strength. This study investigates the structural response of a tugboat’s midship section under various transverse frame spacing configurations using the Finite Element Method (FEM) to optimize lightweight tonnage (LWT) while maintaining seaworthiness. Utilizing structural data from a under-30-meter service tugboat, five distinct frame spacing variations 500 mm (baseline actual design), 550 mm, 575 mm, 600 mm, and 625 mm were modeled using four-node shell elements (SHELL181) within ANSYS software. A constant uniform static deck pressure load of 0.0122 MPa was applied to evaluate localized stress distributions and elastic displacement fields under rigid boundary conditions. Numerical simulations reveal a progressive, linear increase in both equivalent stresses and vertical deflections as the unsupported span of the deck plating expands. The maximum von Mises equivalent stress escalated from 31.4237 MPa at the 500 mm baseline configuration to 34.1552 MPa (550 mm), 35.4687 MPa (575 mm), 36.8590 MPa (600 mm), and peaked at 40.6607 MPa under the widest 625 mm spacing. Concurrently, the total displacement vector sum rose from 0.56047 mm at the baseline to a peak of 0.86030 mm at 625 mm spacing due to the reduction of localized flexural rigidity. Crucially, despite the elevated structural responses, all configurations safely satisfy the strict structural limits enforced by the Indonesian Classification Bureau (BKI 2022) rules, as the maximum peak stress (40.6607 MPa) remains substantially below the nominal upper yield strength of ordinary hull structural steel (ReH = 235 N/mm2). These findings demonstrate that extending the transverse frame spacing up to 625 mm is structurally viable, offering a verified mechanism for weight optimization without compromising structural safety margins.
Influence of Conductor Pipe Diameter on the Global Structural Performance of a Fixed Offshore Wellhead Platform Afriza Akbar Ardiansyah; Luh Putri Adnyani; Jumat Amin; Rahmawati
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8482006

Abstract

Offshore wellhead platforms are continuously subjected to environmental loads from waves, currents, and wind; therefore, structural assessment is required to ensure safe operation, particularly when design modifications are proposed. This study evaluates the influence of conductor pipe diameter variation on the global structural performance of an existing fixed offshore wellhead platform by comparing the existing 20-inch conductor pipe configuration (CP20) with a modified 30-inch conductor pipe configuration (CP30). The assessment was conducted through in-place analysis using SACS software under 1-year operating and 100-year storm conditions. The structural performance was evaluated based on displacement response, member unity check, joint unity check, and pile axial capacity. The results show that both CP20 and CP30 configurations satisfy the strength requirements, with maximum member unity checks of 0.81 under operating conditions and 0.96 under storm conditions, which are below the allowable limit of 1.00. The joint unity checks also remain far below the allowable limit, with values of 0.177 under operating conditions and 0.172 under storm conditions. The pile axial capacity is also satisfactory, with pile safety factors ranging from 29.41 to 34.04 for CP20 and from 29.41 to 30.21 for CP30, which are significantly higher than the minimum requirement of 1.50. However, several displacement responses exceed the allowable limits. The pilehead displacement under storm conditions reaches 6.49 cm for CP20 and 6.51 cm for CP30, exceeding the allowable limit of 5.08 cm. The vertical deck displacement under storm conditions reaches 7.42 cm for CP20 and 7.44 cm for CP30, exceeding the allowable limit of 4.00 cm. In addition, the horizontal displacement exceeds the allowable limit of 3.10 cm under both operating and storm conditions, with values increasing from 5.9194 cm to 8.4834 cm for CP20 and from 5.9294 cm to 8.5323 cm for CP30. These findings indicate that increasing the conductor diameter from 20 inches to 30 inches has a limited effect on global strength capacity but produces a slight increase in displacement response due to the larger hydrodynamic loading area. Therefore, the CP30 modification can be considered acceptable from a strength-capacity perspective, but further evaluation of serviceability performance.
Effect of Bow and Stern Line Angle Variations on the Resistance of a 35,000 DWT Bulk Carrier Using CFD HerawatyMagdalena Sihombing; Anggra Fiveriati; IGNA Satria Prasetya; Abdul Rohman
Indonesian Journal of Maritime Technology Vol. 4 No. 1 (2026): Volume 4 Issue 1, June 2026
Publisher : Naval Architecture Department, Kalimantan Institut of Technology

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35718/ismatech.v4i1.8482015

Abstract

The shipping industry requires hull designs that can reduce hydrodynamic resistance and support energy-efficient vessel operation, particularly for bulk carriers with large displacement and relatively high-power demand. This study investigates the effect of bow and stern line angle variations on the total resistance of a 35,000 DWT bulk carrier using Computational Fluid Dynamics (CFD). The CFD results were also compared with the Holtrop method and Maxsurf Holtrop estimation to assess the consistency of the total resistance prediction trend. The principal dimensions used in the hull modelling were 178 m length between perpendiculars, 185.12 m waterline length, 29.7 m breadth, 14.8 m depth, 10.3 m draft, and a service speed of 16 knots. Three hull models were analysed: Model A as the initial hull configuration with 15.4° stern line angle and 23° bow line angle, Model B with a 1° increase in both the bow and stern line angles, and Model C with a 1° decrease in both line angles. The results show that, at 16 knots, Model C produced the lowest total resistance of 647.070 kN, compared with Model A at 655.434 kN and Model B at 670.372 kN. Compared with the initial hull configuration, Model C reduced the total resistance by 8.364 kN, equivalent to approximately 1.28%. The comparison among the Holtrop method, CFD simulation, and Maxsurf Holtrop estimation showed a similar increasing trend in total resistance with ship speed, with percentage differences of 7.76% between Holtrop and CFD and 5.28% between Maxsurf Holtrop and CFD at the operational speed. Therefore, among the three tested hull model variations, Model C demonstrated the most favourable resistance performance and may contribute to reducing the effective power requirement of the 35,000 DWT bulk carrier.

Page 6 of 7 | Total Record : 62

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