International Journal of Marine Engineering Innovation and Research
International Journal of Marine Engineering Innovation and Research A Sinta-2 accredited open access journal advancing original research and innovation in marine engineering, committed to fast peer-reviewed publishing for academia and industry worldwide. Submit Your Manuscript About the Journal Promoting the innovative marine engineering research and knowledge through open-access, peer-reviewed global collaboration. P-ISSN: 2541-5972 | E-ISSN: 2548-1479 Focus and Scope The International Journal of Marine Engineering Innovation and Research (IJMEIR) is a peer-reviewed, open-access journal dedicated to disseminating original research, innovations, and practical contributions in marine engineering. We welcome high-quality papers from both academia and industry covering all aspects of marine science, technology, and related fields. IJMEIR publishes quarterly issues and offers a fast publication process with broad international visibility and high citation impact. Our commitment is to provide a free platform for researchers worldwide to publish, read, and share valuable knowledge. Our scope includes marine engineering, marine technology, marine sciences, environmental engineering, and associated interdisciplinary areas. We invite you to contribute and advance marine innovation with us. Detailed Scope
Department of Marine Engineering, Institut Teknologi Sepuluh Nopember
Investment Analysis of a Lake Water Treatment System into Drinking Water and Design of the Lake Water Management Supply Chain at MAN IC Paser, East Kalimantan
The availability of safe and sustainable drinking water is a vital necessity for boarding educational institutions. Madrasah Aliyah Negeri Insan Cendekia (MAN IC) Paser faces limitations in the quantity and continuity of clean water supply from external providers, while at the same time possessing a potential surface water source in the form of a lake with a large storage volume. However, the quality of the lake water does not yet meet drinking water standards, as indicated by high turbidity levels and potential microbiological contamination. This study aims to analysis of investment of the design a lake water treatment system into drinking water that complies with the Indonesian Ministry of Health Regulation No. 492 of 2010, as well as to design an efficient and sustainable water management supply chain and ecosystem. The research methods include raw water quality analysis, jar test experiments using several types of coagulants, the design of a water treatment plant (WTP) employing a conventional treatment system, and supply chain analysis based on a systems thinking approach. The results show that a complete water treatment system consisting of presedimentation, coagulation–flocculation, sedimentation, filtration, and disinfection is able to reduce turbidity to meet drinking water quality standards. In addition, the integrated supply chain design supports the operational sustainability of drinking water provision within the MAN IC Paser environment. This study is expected to serve as a model for drinking water self-sufficiency based on local resources in educational institutions.
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Engine Combustion Performance and Emission of a Dual-Fuel NH3-B100 in Yanmar TF-85
This study investigates the combustion characteristics, engine performance, and emission behavior of an ammonia–biodiesel (NH₃–B100) dual-fuel compression-ignition engine based on a Yanmar TF-85 diesel platform using a combined experimental and numerical approach. Three-dimensional (3D) in-cylinder combustion simulations were performed using ANSYS Forte, while overall engine performance was evaluated through a one-way 3D-1D coupling framework integrated with MATLAB. Baseline single-fuel B100 operation was first validated against experimental measurements, yielding prediction errors below [6%] for engine power, confirming the reliability of the simulation model. After validation, ammonia was introduced through intake manifold injection to establish dual-fuel operation. The results indicate that ammonia substitution delays combustion phasing and reduces the peak heat release rate by approximately [22%], leading to decreases in indicated mean effective pressure and brake power of [30%] and an increase in specific fuel consumption of [30%]. In terms of emissions, carbon-related species were reduced, with CO₂ and CO decreasing by up to [60%] and [50%], respectively, whereas NOₓ emissions increased by [20%], and measurable NH₃ slip was observed under high ammonia energy fractions. Overall, the proposed 3D–1D modeling framework provides an accurate and computationally efficient tool for evaluating ammonia–biodiesel dual-fuel strategies and supports the development of low-carbon marine diesel engines.
Risk Assessment Model of Ship Accidents Using Fault Tree Analysis (FTA) Based on Incident Categories and Fatality Factors
Maritime transportation plays a vital role in supporting economic activities and regional connectivity in archipelagic countries such as Indonesia yet ship accidents remain a persistent safety concern particularly when they result in loss of life. This study aims to develop a severity oriented risk assessment model for ship accidents by integrating accident categories and fatality factors using Fault Tree Analysis. The study focuses on identifying dominant causal pathways and critical contributing factors that lead to fatal ship accidents rather than merely examining accident frequency. The research adopts a quantitative analytical design using secondary data obtained from 50 officially documented ship accident cases involving fatalities in Indonesian waters between 2017 and 2022. The dataset includes detailed information on accident categories vessel characteristics and causes of death with a total of 295 recorded fatalities. Fault Tree Analysis is applied to structure the causal relationships between basic events intermediate accident categories and the top event defined as a fatal ship accident. Qualitative analysis is conducted to identify dominant failure pathways and minimal cut sets while quantitative analysis estimates the probability contribution of each basic event based on historical fatality data. The results indicate that sinking and fire accidents are the most critical intermediate events accounting for more than three quarters of total fatalities. At the basic event level human related factors dominate fatal outcomes particularly insufficient access to life saving appliances and ineffective emergency response which together contribute more than half of all fatalities. Technical factors such as fire system failure and toxic gas exposure represent the second most significant contributors while environmental and external factors mainly act as amplifiers that reduce survivability after an accident occurs. The integrated qualitative and quantitative analysis reveals that fatal ship accidents are largely driven by dominant high impact basic events rather than complex combinations of multiple low probability failures. This study contributes to maritime safety research by providing an empirically grounded Fault Tree Analysis model that explicitly links accident categories with fatality mechanisms. The findings offer practical implications for risk based maritime safety management by prioritizing human centered interventions emergency preparedness and fire safety systems. The proposed model provides a robust analytical foundation for policy formulation targeted risk mitigation and future development of life safety oriented maritime risk assessment frameworks.
Effect of Gawn Series Propeller Camber Ratio Variations on Fuel Consumption Using Engine Propeller Matching
Propeller blade geometry, particularly the camber ratio, plays a critical role in determining hydrodynamic behavior and fuel consumption in marine propulsion systems. This study investigates the influence of camber ratio variation on the performance of a Gawn Series propeller by applying an Engine–Propeller Matching (EPM) approach. Open-water performance characteristics, including thrust coefficient (KT), torque coefficient (KQ), and open-water efficiency (η₀), were obtained through Computational Fluid Dynamics (CFD) simulations for four camber configurations of 0%, 1%, 1.5%. The numerical model was validated using resistance and open-water test data, yielding deviations below 5% and 3%, respectively, which confirms the reliability of the simulation results. The analysis shows that higher camber ratios generally increase thrust and torque as a result of strengthened pressure gradients and enhanced flow acceleration along the suction side of the blade, with the 1% camber configuration demonstrating the highest efficiency at J = 0.9 (η₀ = 0.596), representing a 3.85% improvement over the baseline. Matching the resulting propeller load curves with the performance envelope of a 2 × 3900 kW engine setup provides insight into optimal operating conditions and specific fuel consumption across the vessel’s working speed range. The 1% camber variant consistently delivers better fuel economy, maintaining safe operating points. Overall, these results underscore the substantive influence of camber modification on propeller hydrodynamics and propulsion efficiency, identifying the 1% camber configuration as the most suitable option for 60-m high-speed vessels based on combined hydrodynamic, fuel, and operational criteria within the EPM framework.
Cooling Media Treatments of the Welding Result of Aluminium 5083 using Gas Tungsten Arc Welding (GTAW) on Material Strengths
Cooling treatment will occur in every welding process. In welding construction of Aluminium raw materials using the Gas Tungsten Arc Welding (GTAW), sometimes carried out in different locations and conditions. The study aims to determine and analyses the treatment effect of variations cooling media using air, fresh water, and sea water on the material strength (tensile strength, bending strength and hardness) welding results of aluminium 5083. This research method is experimental by testing specimens of welding results. Data analysis with independent variables of air, fresh water, and sea water cooling media. The dependent variables are tensile strength, bending strength, intervening variable of hardness and as a control variable, Aluminium 5083 the same size of 300x150x6mm. The test results with air media cooling treatment obtained data, the direct cooling treatment the tensile test value was 193Mpa, the bending test was 61Kgf/mm2, the hardness test 63HRB, the media cooling treatment was flowed at a speed of 2,8m/s, the tensile test value was 178Mpa, the bending test was 49Kgf/mm2, the hardness test 55HRB and the media cooling treatment was flowed at a speed of 4,2m/s, the tensile test value was 157Mpa, the bending test was 55Kgf/mm2, the hardness test 59HRB.
Structural Integrity and Edge Stiffness Evaluation of GFRP Modular Towing Tank: Analytical and Numerical Study
Conventional hydrodynamic testing facilities require substantial capital investment, limiting maritime research accessibility in developing nations. This study addresses the structural integrity and global stiffness challenges in designing a modular Glass Fiber Reinforced Polymer (GFRP) composite towing tank as a cost-effective alternative. A hybrid laminate configuration combining Chopped Strand Mat 450 g/m² and Woven Roving 800 g/m² was analyzed under hydrostatic loading using Classical Laminate Theory (CLT) and Finite Element Method (FEM). Analytical predictions indicated acceptable performance with 26.09 MPa bending stress and 5.95 mm deflection under fully clamped boundary assumptions. However, full-scale FEM simulation revealed critical free-edge effects, producing 41 MPa Von Mises stress and 62 mm deflection at the tank rim exceeding the L/200 serviceability limit despite maintaining a safety factor of 3.65. This study demonstrates that while the 19 mm wall thickness satisfies strength requirements per ASME RTP-1 standards, edge stiffening through horizontal rim reinforcement is essential to control excessive deformation in open-top modular configurations.
Input and Output of Tuna Fishing Operations Using Longline Vessels Based at Cilacap Ocean Fishing Port
Tuna fishing not only generates significant economic profit, but also has negative environmental impacts due to the intensive use of materials, equipment, and energy. This study aims to identify and measure the input and output components of the tuna fishing process using longline vessels at the Cilacap Oceanic Fisheries Port through a life cycle inventory (LCI) approach. Data collection was carried out through field observations and structured interviews with 30 selected stakeholders, including the analysis of vessel specifications, fishing gear, and supplies. The results of the study show that supplies dominate operational inputs with a total mass of 62,026 kg/year. This indicates a high resource intensity, requiring 29.31 kg of material input to produce 1 kg of tuna. In addition, this activity produces outputs in the form of significant environmental impacts, including Sulfur Oxide (SOx) emissions of 707.62 kg/year due to diesel fuel combustion and solid waste of 33,550 kg/year, predominantly consisting of single-use plastic packaging from leftover supplies. These findings indicate the need for improvements in logistics components from the upstream side and waste management strategies in the fisheries sector.
Risk Assessment and Mitigation Strategy of Hybrid Energy Storage System in 11-m Fully-Electric Seabus
Risk assessment of Energy Storage Systems (ESS) in ships is a fundamental requirement to ensure operational safety in the maritime sector. This study investigates risk analysis and mitigation strategies for a Hybrid Energy Storage System (HESS) applied to a 11-meter fully-electric Seabus, configured with Lithium Iron Phosphate (LFP) and Lithium Titanate Oxide (LTO). The Hazard Identification (HAZID) method is employed to systematically identify potential hazards during operation, covering technical, operational, and environmental aspects. The findings reveal that hazards with the highest risk ranking include explosion and battery fire, both of which pose severe threats to vessel safety and environmental integrity. To address these critical risks, appropriate mitigation strategies are proposed, including advanced battery management systems, physical protection of critical components, and emergency operational procedures tailored to maritime safety standards. This research highlights the importance of integrating HAZID into the design and operation of HESS to enhance reliability and safety
Analysis Posture Work For Reduce Risk of Musculoskeletal Disorders (MSDs) With REBA Method in Wooden Ship Manufacturing Industry
In the current industrial era, work intensity will increase along with consumer demand. As a result, the workload received by workers must be considered, regardless of whether it is a low, medium, or high workload. The focus of this study is on the workload borne by workers who work in the wooden ship manufacturing industry at a company that produces wood as the main material for making wooden ships. Lifting, cutting, and assembling are jobs that are often done in the production section, which require many repetitions and long times. Therefore, it can be concluded that these activities have a very high risk and have a dangerous impact on workers to experience muscle or bone injuries. The Nordic Body Map (NBM) questionnaire was used to conduct an initial measurement of the workload risk received by workers to determine the risk of workload received. The results showed a high value for complaints of Musculoskeletal Disorders (MSDs). Furthermore, further measurements of ergonomic risks were carried out using the Rapid Entire Body Assessment (REBA) method , so that design steps can be taken to improve work posture using the CATIA application to reduce the level of complaints that occur.
CFD Simulation of Engine Room Ventilation Systems: A Case Study of TB Hasnur 08 Tugboat Main Engine
Excessive heat in the engine room of the tugboat TB Hasnur 08 represents a critical operational issue, as it directly affects operator comfort, main engine combustion efficiency, and the overall reliability of onboard machinery systems. This study aims to design, evaluate, and validate an optimal engine room ventilation model using a Computational Fluid Dynamics (CFD) approach. The analysis focuses on identifying heat pocket locations, evaluating various airflow arrangements, and formulating data-driven ventilation design guidelines. The calculation of air supply requirements and heat evacuation is conducted in accordance with ISO 8861:1998, which serves as the primary reference standard. The research methodology consists of an empirical study followed by CFD simulations. The simulations examine variations in air velocity and airflow configuration through the application of exhaust systems, resulting in five ventilation configurations, referred to as Variation 0 to Variation 4. Under existing conditions (Variation 0), the engine room air temperature ranges from 45.05°C to 46.05°C. Variation 1 reduces the temperature to 42.85°C–43.95°C, while Variation 2 achieves 42.85°C–42.95°C. Variation 3 applies air velocity in compliance with ISO 8861, resulting in a further reduction to approximately 41.85°C–42.95°C. Variation 4 utilizes the same air velocity as Variation 3 with an additional exhaust duct at Frame 16/17, producing temperatures of 42.85°C–43.25°C. The results indicate that Variation 3 provides the most effective temperature reduction. Furthermore, CFD analysis demonstrates strong capability in predicting thermal behavior resulting from changes in air velocity, duct dimensions, and ventilation configurations.
Analysis of Causes and Impacts of Tug and Barge Vessel Accidents Using the Analytic Hierarchy Process: A Case Study of XYZ Company
Indonesia’s maritime sector plays a strategic role in national logistics, where tug and barge vessels are widely used to transport bulk commodities due to their cost efficiency and operational flexibility. However, tug and barge operations face a high risk of accidents, particularly in densely trafficked waterways and challenging environmental conditions. This study aims to analyze the causes and impacts of tug and barge vessel accidents at Company XYZ during the period 2015–2024 and to determine priority mitigation measures using the Analytic Hierarchy Process (AHP). The study analyzes 170 recorded accident cases classified into human, technical, environmental, and procedural factors. The results show that human factors are the dominant cause, contributing 55.8% of accidents, followed by technical factors (26.3%), environmental factors (12.2%), and procedural factors (5.7%). The accidents resulted in material losses, operational delays of 3–7 days per incident, and environmental impacts such as fuel spills and onboard fires. The AHP results indicate that human-related factors are the highest priority for mitigation, followed by technical, environmental, and procedural factors, with a consistency ratio of 0.043, indicating acceptable reliability. This study provides a structured decision-making approach to support safety improvement and risk mitigation in tug and barge vessel operations.
Experimental Study on Extinction Curve Fitting Expressions of Ship Roll Damping
Roll damping plays a crucial role in the accurate prediction of ship roll motion. In potential flow theory, viscous roll damping is not inherently accounted for and therefore must be introduced through experimental model test results. Free roll decay tests are commonly conducted to determine roll damping characteristics, including both linear and nonlinear damping (quadratic) components. In experimental practice, roll damping coefficients obtained from roll decay tests are often expressed using different mathematical formulations, such as linear, quadratic, and Bertin’s equations. In this study, free roll decay tests were performed on three ship models, and the resulting roll decay responses were analyzed using the three damping expressions for curve extinctions of measured data. The linear and quadratic roll damping coefficients were extracted for each model and formulation. The results indicate that the selected extinction curve expression and fitting method significantly influence the estimated roll damping coefficients. In addition, the choice of using peak-to-peak or trough-to-trough data in the roll decay analysis was found to affect the obtained damping values. Based on the comparative analysis, it is concluded that averaging the damping coefficients derived from both peak-based and trough-based fitting provides a more representative estimation of roll damping for the tested ship models.
Intelligent Optimization of Fast Boat Hull Form for Resistance Reduction Using CFD and Surrogate-Assisted Algorithms
High-speed fast boats operating at high Froude numbers experience rapidly increasing resistance due to coupled viscous and wave-making effects. This study proposes a surrogate-assisted hull-form optimization framework that combines Reynolds-averaged Navier-Stokes (RANS) CFD (SST k-ω) with Gaussian Process Regression (Kriging) to minimize the total resistance of a fast monohull while maintaining displacement and geometric feasibility. The hull geometry was parameterized using four variables: deadrise angle, prismatic coefficient, longitudinal centre of buoyancy (LCB), and bow entrance angle. A set of candidate designs was evaluated by CFD, a surrogate model was trained and validated (R² = 0.985, prediction error < 2%), and global optimization was carried out using Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). CFD verification of the best design shows a consistent resistance reduction across Fn = 0–0.75, with a maximum reduction of 14.4% at Fn = 0.65 compared to the baseline hull. The optimized hull exhibits reduced bow pressure peaks and delayed flow separation at the transom. The surrogate-assisted strategy reduces the number of CFD evaluations and lowers the overall computational effort by about 78% while preserving prediction accuracy. R^2=0.992.
Improvement of Impinging Jet Casing Design On Savonius Turbine Performance
Savonius turbine is one of the various devices used to convert fluid flow energy into electricity. Due to its low efficiency, many studies have been conducted to increase its performance. In this paper, the effect of impinging jet stream direction to concave side of returning blade has been observed. There are 4 casing designs; base casing design (BCD) from previous work and 3 proposed designs which have impinging jet stream direction perpendicularly with the concave side of returning blade azimuth position of 60° (D-I), 75° (D-II), and 90° (D-III) respectively. The study employed two-dimensional CFD (Compu-tational Fluid Dynamic) transient method using Ansys Fluent with Kω-SST (Shear-Stress Transport) as the turbulence model. The result shows that all casing designs are able to rise up the coefficient of power (Cp) of conventional turbine design. Furthermore, D-III and D-II have better performance than BCD at all tip speed ratios (TSRs) while D-I’s Cp curve shows several intersections. D-III surpasses BCD’s peak performance, At TSR =1, by 8%. By applying D-III casing design, the best caseless turbine efficiency (23%) could be improved up to 43% at the same working condition (TSR=0.8). Additionally, the shorter flow passage could increase the impinging jet stream velocity
Fatigue Life Amphibious Floater based on RAO Slamming Pressure
Floater is one of the most important part of amphibious version plane and conducting study of it becomes one of the featured research to support Indonesia’s transportation. This paper examined general study of amphibious floater slamming load when landing on the water in the various plane landing situation, starting from stern 5°, stern 10°, bow 5°, bow 10°, heel 0°, heel 5° and heel 10°. Carbon Fiber Reinforced Polymer (CFRP) material is used with 20 and 40 mm thickness. Floater consists of three main parts which are base, keel, and frame. Seaplane is designed to withstand 1000 cycle (500 landing and 500 take off cycle) in a year. This paper confirms that with the thickness of 20 and 40 mm, and heel position of 0°, floater can withstand up to 65,535 years. In contrary, using the 20 and 40 mm layer when landing with any combination position, the floater can’t last and only has 0.01 year of fatigue life.
A Preliminary Research Design and Model Determinants of Ship Accident Risk in Indonesia: The Roles of Competence, Work Stress, Communication, and Supervision through Safety Culture
Indonesia is the world’s largest archipelagic state, where sea transport is the backbone of passenger and cargo mobility, yet ship accidents remain frequent and often highly fatal. This paper proposes and tests a structural model linking four human-factor dimensions—crew competence, work stress, communication effectiveness, and supervision—to perceived ship accident risk in Indonesia, with safety culture as a mediating variable. A quantitative survey is conducted among 300 seafarers operating in three major maritime regions (Batam, Merak, and Bali), and data are analyzed using Structural Equation Modeling (SEM) following recommended rules of thumb for sample size and model evaluation. The study aims to identify the most influential human-factor determinants of perceived accident risk and to provide evidence-based recommendations for strengthening maritime safety culture.
Integrating Green Marine Technology into Maritime Education in Indonesia
Indonesia’s maritime sector faces rising pressure to decarbonize ships and ports while maintaining safety and competitiveness. This paper examines how green marine technologies can be embedded into maritime vocational education so graduates are ready for shipboard and port-side sustainability initiatives (energy efficiency, emissions reduction, waste management, and alternative energy systems). An exploratory mixed-method design was used: semi-structured interviews with nine stakeholders (industry practitioners, maritime educators, and recent graduates) were complemented by a simple stakeholder rating instrument to assess curriculum integration, sustainability awareness, and industry relevance. Thematic analysis identified recurring needs and implementation constraints, while the ratings helped prioritize actions. Findings indicate that sustainability topics are present but unevenly distributed across courses and often lack measurable competency targets. Project-based learning and case studies were perceived as the most effective approaches, especially when supported by simulator/lab facilities and industry co-teaching. The strongest gap lies in translating regulations and green-technology concepts into practical marine-engineering tasks and assessment rubrics. The paper proposes priority actions for curriculum owners: competency mapping to green shipping operations, structured industry feedback loops, and incremental upgrading of learning infrastructure. These steps can strengthen graduate employability and accelerate sustainable practice adoption in the maritime industry.
Evaluation of Boiler Maintenance Using The Failure Mode and Effect Analysis Approach at KM. Tilongkabila
Boilers experience frequent problems, such as scale formation, unstable steam pressure, incomplete combustion, and difficulty starting. Therefore, this study uses a quantitative method with the Failure Mode and Effect Analysis (FMEA) approach, which aims to determine maintenance and prevention to minimize these problems. This method determines the failure priority obtained from the Risk Priority Number (RPN) calculation based on assessment factors such as severity, frequency of occurrence, and the likelihood of failure being detected in each component. The results of these calculations indicate that the steam drum component falls into the highest category, with an RPN of 32. The other 12 components fall into the medium category: the feed water pump, electrode, photocell, nozzle, blower fan, solenoid valve, fuel pump, blowdown valve, main steam valve, scum valve, non-return valve, and gauge glass, with RPN values ranging from 12 to 24. Furthermore, the components in lowest category include the fuel filter, safety valve, and manometer, with RPN values ranging from 8 to 10. Therefore, the recommended improvements based on the FMEA results can be used as evaluation material to ensure the effectiveness of the improvements. Furthermore, regular boiler maintenance and monitoring are required, especially for components such as the steam drum, which requires additional routine maintenance schedules, repeated evaluations related to water treatment, and determining appropriate repairs for any steam drum failures.
Implementation Review of Indonesia’s Measured Fishing Policy (PIT) Supporting Sustainable Tuna Fishery in Banda Aceh
The Indonesian Government has implemented the Measured Fishing Policy (PIT) through Government Regulation No. 11 of 2023 as an effort toward sustainable fisheries management. This policy regulates measured fishing according to fish resource potential within each Fisheries Management Area of the Republic of Indonesia (WPPNRI). The PIT policy has been applied in several regions, including Banda Aceh City, yet faces challenges such as limited port infrastructure, low local fishers’ awareness, and a lack of empirical data on its impacts on fishing productivity and welfare. This study aims to analyze changes in the productivity and income of tuna, skipjack, and frigate tuna fishers before and after PIT implementation in Banda Aceh. A mixed-methods approach was employed, combining production and fishing effort data from the Kutaraja Ocean Fishing Port (PPS Kutaraja) with in-depth interviews with fishers and stakeholders. Results show that tuna production peaked in 2024 at 395.35 tons/year and was lowest in 2021 at 33,99 tons/year. Skipjack production reached 1.502,79 tons/year, while frigate tuna production was highest in 2024 and lowest in 2022 (75.15 tons/year). Income analysis revealed that purse seine fisher’s profits were influenced by vessel, engine, gear investments, and operational and maintenance costs. In conclusion, the PIT policy affects the dynamics of local fishers’ productivity and income, providing an empirical basis for strengthening sustainable fisheries policy at the local level.
Regulation-Based Safety Redesign of Electric Forklift Charging Panel
The increasing use of electric forklifts in industrial environments requires charging power supply systems that are technically reliable and compliant with updated electrical safety regulations. However, empirical studies evaluating the regulatory compliance and safety risks of electric forklift charging panels—particularly under Indonesia’s Minister of Energy and Mineral Resources Regulation No. 1 of 2023—remain limited, indicating a clear research gap. This study aims to assess the compliance level of an existing electric forklift charging power supply panel and to propose a redesigned panel that meets regulatory and safety requirements. An observational assessment was conducted using a structured compliance checklist derived from ESDM Regulation No. 1 of 2023, covering protection systems, grounding, monitoring instruments, labeling, and operational safeguards. Quantitative compliance scoring and risk-based evaluation were applied to identify technical deficiencies and associated electrical hazards. The results show that the existing panel complies with only 58% of mandatory requirements and presents several high-risk conditions, particularly due to inadequate protection devices, lack of electrical monitoring, and insufficient grounding. A redesigned single-line diagram was subsequently developed and evaluated, achieving 100% compliance with mandatory and recommended criteria. The proposed design significantly reduces electrical safety risks, improves system reliability, and ensures full regulatory compliance, providing a practical reference for the development of safe and reliable industrial electric vehicle charging infrastructure.
Design and Construction Fish Cool Box Using Combined Aluminum and Ethylene Vinyl Acetate (EVA) Materials
Abstract¾ Indonesia is one of the world’s leading producers and exporters of fresh and frozen fish; however, the economic value of its fishery exports remains relatively low due to quality deterioration caused by inadequate post-harvest handling, particularly during onboard storage. Small-scale fishers predominantly use conventional storage media such as styrofoam or fiber-based cool boxes with block ice, which often provide insufficient insulation and poor temperature stability. This study aimed to evaluate the thermal performance and ice utilization efficiency of an innovative laminated cool box constructed using a combination of aluminum plate, aluminum foil, ethylene-vinyl acetate (EVA) sponge, and fiberglass, compared with a conventional fiber-based cool box. An experimental design with two treatments and three replications was applied over a four-month period at the Capture Fisheries Laboratory, Politeknik Negeri Lampung. Cooling performance was assessed through optimal cooling tests, 24-h and 48-h temperature performance evaluations, ice efficiency analysis, and statistical comparison using an independent samples t-test. The results showed that the innovative cool box achieved a lower minimum temperature (−3 °C) and a faster cooling rate (0.50 °C min⁻¹) than the standard cool box (−1 °C; 0.29 °C min⁻¹). During the 48-h test, the innovative cool box maintained temperatures below 4.4 °C for up to 18 h, significantly longer than the standard cool box. Although the ice utilization efficiency of the innovative cool box (26.16%) was lower than that of the standard cool box (30.80%), its overall cooling performance and thermal stability were superior. These findings demonstrate the potential of the innovative cool box to improve fish quality preservation and support higher economic value in fisheries post-harvest handling.
Comparative Thermal Analysis of Turboprop and Turbofan Engines Ideal Brayton Cycle Efficiency and Performance Implications
Comparative thermal analysis of turboprop and turbofan engines in aircraft propulsion systems, with a focus on ideal thermal efficiency based on the Brayton cycle. Thermal efficiency, a dimensionless parameter representing the ratio of heat converted into useful work to the total heat input, is a fundamental indicator of engine performance and energy utilization. Turboprop engines, such as the Garret TPE331-10 powering the CASA C-212 Aviocar, operate as hybrid systems generating both jet thrust and shaft power for propeller rotation. In contrast, turbofan engines, exemplified by the CFM56-3CI, utilize a large bypass fan to achieve higher mass airflow and improved thrust efficiency at subsonic cruise conditions. This study quantitatively evaluates and compares the ideal thermal efficiencies of both engine types using data from previous studies. The analysis reveals that the CFM56-3 turbofan achieves an ideal thermal efficiency of approximately 70.51%, significantly higher than the TPE331-10 turboprop's 48.99%. This 21.52 percentage point difference is primarily attributed to the turbofan's higher compressor pressure ratio, enabling more effective energy conversion within the Brayton cycle. However, the paper also discusses the trade-off between thermal efficiency and propulsive efficiency, noting that turboprops excel at low to medium speeds due to superior propulsive efficiency from their propellers. The findings underscore that while turbofans are better suited for high-speed, long-range flights, turboprops remain optimal for short-haul operations. This comparison provides valuable insights for engineers, designers, and operators in selecting appropriate propulsion technologies and optimizing energy use across various flight missions.
Reaction Time-Based Fatigue Analysis in Construction Workers
Occupational fatigue in construction projects remains a critical safety issue, yet its assessment is commonly based on subjective questionnaires and interviews that may not accurately reflect real-time physiological performance. This study aimed to analyze the relationship between biological factors and work-related factors and the level of work fatigue among construction workers using Digital Reaction Timer measurement as an objective indicator. A cross-sectional study was conducted involving active construction workers, where fatigue was quantified using a digital reaction timer as an objective human performance indicator. Biological factors such as age, gender, sleep duration, and nutritional status, as well as work-related factors including working hours, shift patterns, workload, and work experience, were statistically analyzed against reaction time results. The findings show that reaction time measurement can differentiate fatigue levels and identify significant determinants affecting performance degradation. Several biological and occupational variables were associated with increased reaction time, indicating higher fatigue levels. The results demonstrate that an engineering-based digital measurement approach provides a more objective and quantifiable fatigue assessment compared to traditional self-reported methods, supporting data-driven safety management in high-risk construction environments.
Adaptation Mechanisms and Resilience of Small-Scale Fishermen's Livelihoods to the Impacts of Climate Variability in Central Tapanuli Regency, North Sumatra
Climate variability is increasing the vulnerability of small-scale fishing communities, especially in coastal areas that are highly dependent on fishery resources as their main source of livelihood. This study aims to identify fishermen's adaptation mechanisms, analyze their level of resilience, and determine the factors that influence the resilience of small-scale fishermen in two coastal villages in Central Tapanuli Regency, namely Teluk Roban Village and Pasar Sorkam Village. This study uses a quantitative survey approach with purposive sampling techniques on 70 fishing households consisting of 35 fishermen in Teluk Roban Village and 35 fishermen in Pasar Sorkam Village. The data were analyzed using statistical analysis to identify factors that influence the resilience of fishing households. The results of the study show that the resilience of fishing households in Teluk Roban Village is significantly influenced by education levels, access to financial institutions, livestock ownership, and the size of the fishing fleet. Meanwhile, the resilience of fishing households in Pasar Sorkam Village is more influenced by the age of the head of the family, non-fishing income and access to natural capital such as mangrove forests, rice fields, and mango and coconut trees. Despite differences in livelihoods, the level of resilience of fishing households in both villages does not show significant differences and is generally in the moderate category. These findings indicate that diversification of livelihoods, access to financial resources, and utilization of natural capital are important factors in strengthening the adaptive capacity of fishing households to climate variability.
The Effect of Current, Cr2O3 and MnO2 Active Flux to The Depth of Penetration and Microstructure of A-TIG 5083 Aluminium Welding
Materials with a thickness exceeding 5 mm require at least two layers of TIG welding; however, this challenge can be addressed through A-TIG welding. A-TIG welding utilizes an active flux to increase penetration without requiring changes to welding parameters. This research investigated the effects of current intensity and the use of Cr2O3 and MnO2 active fluxes on depth of penetration, microstructure, and hardness. The study employed A-TIG welding on 5083 aluminum with current variations of 100 A, 130 A, and 160 A. Results indicated that Cr2O3 active flux at a current of 160 A achieved the deepest penetration of 5.7 mm, while MnO2 at 100 A yielded the highest average hardness of 77.96 kgf/mm2. Regarding microstructure, no significant changes were observed in the base metal across both fluxes; however, grain growth in the weld metal was more pronounced than in the Heat Affected Zone (HAZ) and base metal. Ultimately, Cr2O3 provided greater depth of penetration and a more dispersed distribution of Mg2Si precipitates, whereas MnO2 demonstrated a superior effect on hardness compared to Cr2O3.
Predictive Health Monitoring of a Marine Propulsion Plant Using Multi-Output Random Forest Regression
The reliability of naval propulsion systems is closely related to the degradation of critical gas turbine components, particularly the compressor and turbine. This study proposes a machine-learning-based predictive health monitoring framework for a naval propulsion plant using the Naval Propulsion Plant dataset. The framework was developed from 11,934 observations, 14 operational variables, and 2 degradation targets, namely the compressor decay state coefficient and turbine decay state coefficient. A multi-output Random Forest regressor with 500 trees was employed to simultaneously predict both degradation indicators. The methodology included data preprocessing, exploratory data analysis, model development, performance evaluation, feature importance analysis, and health index formulation. The model achieved an MAE of 0.1899, RMSE of 0.2992, and R² of -0.0484 for the compressor decay state coefficient, while the turbine decay state coefficient achieved an MAE of 0.1604, RMSE of 0.2667, and R² of 0.1814. To improve practical interpretability, the predicted degradation outputs were transformed into a health index and classified into GREEN, YELLOW, and RED conditions. The results showed that 2,387 testing observations were classified as GREEN. The novelty of this study lies in integrating multi-output degradation prediction, feature-based interpretability, and health-index-based condition classification within a single predictive maintenance framework for naval propulsion systems.
Behavior Propagation of Surge Tsunami in Casuarina Equisetifolia Forest
The tsunami disaster in the Indian Ocean on 26 December 2004 had an impact that killed more than 300,000 worldwide and caused catastrophic damage to infrastructure. Indonesia is a tsunami-prone country because it is located between two plates that have great potential for collision, that are the Eurasian plate and the Indo-Australian plate. One of the efforts to mitigate the tsunami disaster is to create protection in the form of natural protection (coastal forests). Tsunamis that move closer to the coast are in the form of surge waves similar to waves resulting from a dam break. The change in depth from the deep sea towards the coast results in an increase wave height, but a decrease in wave velocity. This research was conducted using a physical model simulation approach in the laboratory, using a dam break-based tsunami wave generation method by making a simulation of the flume used measuring 16.80 m x 1.0 m x 0.8 m equipped with a dam break gate. Making a model of a casuarina forest is done by observing and measuring tree dimensions, plant spacing and density. The research results show that there was a decrease in water velocity for the tsunami model d0 = 60 cm for the model without canopy 1 m is 21.09%, 2 m is 29.36%, and 3 m is 36.50%. The decrease surge velocity due to the model with canopy 1 m is 21.71 %, 2 m is 29.67 %, and for 3 m is 40.40 %. For the velocity function to be changed to f V (m, L, n, x). The tree canopy effect is quite effective for high tsunamis but for low tsunami it is not effective, because the tsunami surge will propagate through the tree trunks below canopy.
Impact of Wingsail Integration on Seakeeping Performance and Stability of a Fishing Vessel
Reducing fuel consumption in fishing vessels has become an important issue in improving the efficiency and sustainability of maritime operations, particularly for small and medium-scale fisheries. One potential approach is the integration of wind-assisted propulsion systems such as wingsails. However, the addition of structures above the deck may influence vessel stability and motion responses in waves. This study evaluates the effect of wingsail integration on the seakeeping performance and intact stability of a fishing vessel operating in Benoa, Bali. The reference vessel has principal dimensions of LOA 33.50 m, LPP 29.65 m, breadth 7.95 m, depth 4.06 m, draft 2.90 m, and displacement 415.6 tons. Analysis is conducted using Maxsurf Stability for intact stability assessment and Maxsurf Motion for seakeeping analysis. The seakeeping evaluation considers wave headings of 90°, 135°, and 180° with vessel speeds of 6, 8, and 10 knots, while sea conditions are derived from Beaufort scale conversion. Vessel motions are assessed using RMS, MSI, and MII according to STANAG 4154, while stability is evaluated under departure, fishing ground, and arrival load cases based on IMO Intact Stability Criteria.
Thermo-Environmental Performance Analysis of Cascade Refrigeration System on Cruise Ship Applications
This study analyzes the thermo-environmental performance of cascade refrigeration systems applied to cruise ships to support energy efficiency improvement and emission reduction in accordance with MARPOL Annex VI regulations. Cruise ships have high energy demands, particularly in cooling systems that significantly contribute to overall energy consumption and environmental impact. This research aims to evaluate the effect of operating parameters and refrigerant selection on system performance using exergy efficiency, Ecological Coefficient of Performance (ECOP), and Total Equivalent Warming Impact (TEWI) as evaluation indicators. A thermodynamic model based on mass, energy, and exergy balance equations is applied, with simulations conducted under various operating temperatures and refrigerant combinations. The results indicate that increasing operating temperature from 275 K to 295 K reduces exergy efficiency and ECOP due to increased irreversibility, while TEWI rises significantly as a result of higher energy consumption. Hydrocarbon refrigerants such as R600a/R290 and R152a/R290 show the best performance in terms of both energy efficiency and environmental impact. In contrast, CO₂-based combinations tend to exhibit lower efficiency and higher environmental impact under certain conditions. Overall, selecting appropriate refrigerants and optimizing operating conditions are essential to achieve a balance between system efficiency and environmental sustainability in marine refrigeration systems.
Digital Transformation of Ship Administrative Systems to Enhance Operational Efficiency in Maritime Education Institutions
The management of ship administrative systems in maritime education institutions remains predominantly manual, fragmented, and vulnerable to documentation errors, certification lapses, and operational inefficiencies. As training vessels serve both educational and operational functions, ineffective administrative processes may disrupt academic activities, regulatory compliance, and maintenance scheduling. This study aims to design and evaluate a digital ship administrative management system to enhance operational efficiency and regulatory compliance in maritime education institutions. The research adopts a system development approach consisting of requirement analysis, system architecture design, prototype development, and performance evaluation. The proposed system integrates digital certificate monitoring, automated expiry notifications, document tracking, and a centralized dashboard for real-time administrative status monitoring. System performance is evaluated using operational efficiency indicators, including document processing time, error reduction rate, and administrative readiness level. The results demonstrate that the implementation of the digital administrative system significantly improves document accessibility, reduces processing delays, and enhances compliance monitoring. The centralized dashboard enables proactive decision-making and minimizes the risk of certification expiration. This study contributes to maritime engineering management by providing a practical digital transformation framework tailored for maritime education institutions, supporting the transition toward smart maritime governance and Industry 4.0 practices.