International Journal of Marine Engineering Innovation and Research

Determination of Potential Zones for Website-Based Small Pelagic Fish in Banten Bay Waters

Ayang Armelita Rosalia — 2025-12-05

The waters of Banten Bay have abundant resources of small pelagic fish. Anchovies, mackerel, Shortfin scad, goldstripe sardinella, selar fish, mullet, and lemuru are small types of pelagic fish that can be found all year round in the waters of Banten Bay. Based on its abundant potential, however, its utilization is still inefficient because most local fishermen still use traditional fishing methods, which result in low catches and incomes. The purpose of this study is to develop a website-based system to determine the Fishing Potential Zone (FPZ) in the waters of Banten Bay by utilizing sea surface temperature (SST) and chlorophyll-a data from Aqua MODIS satellite imagery in 2023. Data processing is carried out with SeaDAS and ArcGIS software to determine FPZ points that are implemented in the form of a website, namely FishZone Mapper. The FishZone Mapper website is designed to provide information that can be easily accessed by fishermen, researchers, and other stakeholders to improve fishing efficiency. The results showed that there was a significant difference in the number of FPZ points in the western and eastern seasons, which affected fishing strategies.

Analysis Study of the Water Quality of Siombak Lake Medan North Sumatera

Rahmadhani Fitri — 2025-12-05

Siombak Lake was formed due to land excavation for the construction of the Belawan - Medan - Tanjung Morawa (BELMERA) toll road, which spans 34 km. Frequent tidal flooding in this lake threatens tourism activities and surrounding settlements, leading to changes in the lake's water environment quality. The water quality of Siombak Lake, as part of water spatial planning, is the subject of this study. Regulation of the Minister of Environment No. 115 of 2003 established the Storet method for this study. The results show that the water in Siombak Lake is brackish and experiences daily tidal fluctuations. The Belawan River, which flows into the Malacca Strait, influences the tides of Siombak Lake. Siombak Lake is an open water body affected by tides. It is saline and has high oxygen levels. The high phosphate levels indicate that these waters are already polluted.

Analysis of Berthing Safety using Maneuvering Simulation and Berthing Aid System

I Putu Sindhu Asmara — 2025-12-05

Collisions of ships to cranes in container terminals are attracting attention from the maritime safety community. This paper provides a berthing safety analysis using the berthing aid and automatic identification systems. First, a berthing aid system is developed to measure berthing safety, as speed and angle indicate. The berthing aid system installed in a berth consists of two laser sensors to measure ships' distances, speed, and heading during the berthing maneuver. Second, a berthing maneuver simulation is conducted to determine tugboat elements, consisting of the number and capacity of tugboats, using a time series of thrust power and direction. The elements are simulated to achieve the berthing safety indicated by the time series of speed over the ground, course over the ground, and the ship's heading angle relative to the berth. The monitoring of ship trajectory using an automatic identification system in the port area and berthing safety parameters along the end stage of the berthing maneuver using the berthing aid system has been implemented in this research. The measurement proved that the berthing maneuvers comply with the requirements.

Risk Analysis of Supply Chain in the Construction of Power Plant Barge Using Failure Mode and Effect Analysis (FMEA) Method

Timbul Guntoro — 2025-12-05

Power Plant Barge is a Barge / Barge that functions as a Power Plant with the ability to produce 60 MW of electricity production and has the mobility to be moved from one place to another with a towing system using a Tugboat. The purpose of this research is to analyze supply chain risks in the procurement process that affect the delay in ship construction. This research is to complement previous research that has analyzed the Production process. From the research results, the number of risk events can be identified. A questionnaire was prepared to determine the risk weight using the Failure Mode and Effect Analysis (FMEA) method. There are how many risk events with a high Risk Priority Number (RPN) that affect the delay in barge construction. The results showed an assessment score in the form of a Risk Priority Number (RPN) consisting of activities: The calculation of the estimated material list is revised due to the minimum order with a score of 235.98, The length of the engineering evaluation process (Evatek) with a score of 275.99, Shipping Documents are often sent late by importers with a score of 262.00 and material status is still Eigen Loosing with a score of 169.13. Develop a mitigation strategy to prevent the risk from recurring. There are 8 mitigation steps that can be taken based on the results of discussions with expert practitioners in the shipping industry as described in Table 4.17 regarding developing mitigation strategies such as seeking data from manufacturers regarding minimum orders for steel plates and profiles, coordination with suppliers regarding manufacturing data during Engineering evaluation, Shipping and Customs processes and receipt of materials must be faster, so that potential delays to the shipbuilding process can be avoided.

Mechanical Characteristics of Glass Fibre Vessels

Ali Azhar — 2025-12-05

Glass fibre vessels in Indonesia, which has thousands of islands, are increasingly used due to their relative low price, light weight, corrosion resistance, and low maintenance costs. However, the aggressive marine environment such as exposure to salt water, ultra violet light, temperature changes, and repeated mechanical loads, affect the service life of this material. Determining the mechanical characteristics of glass fibre vessels is important to prevent structural damage that compromises safety and operations. The purpose of this research is to identify and analyse the condition of shipyards, fibreglass vessels that have been in operation, and examine the mechanical characteristics of glass fibre vessels. The research methods used are literature studies and field surveys to shipyards, glass fibre ships, and testing mechanical characteristics with tensile tests and bending tests. The results obtained from this study are the identification of the condition of the glass fibre shipyard, the condition of the operating glass fibre ship, and the mechanical characteristics of glass fibre ships mostly do not meet the standards of the Indonesian Classification Bureau. Recommendations to improve the quality of production are the location, method, labour, design and materials such as ship resin and laminate layers used during the production process have met and obtained certification set by the Indonesian Classification Bureau.

Risk Assessment of FCAW-GS Welding on TKY Joints in Offshore Wind Farm Jacket

Iwan Tri Prasetyo — 2025-12-05

Offshore wind farms are vital in supporting the global energy transition, requiring high structural integrity, particularly in welded T-K-Y joints of jacket foundations. These joints must endure harsh marine environments and dynamic loads, making weld quality a critical factor. This research aims to identify, analyze, and mitigate the risks associated with Flux Cored Arc Welding – Gas Shielded (FCAW-GS) on T-K-Y joints in offshore wind farm jacket construction using the Failure Mode and Effect Analysis (FMEA) method. The study used expert surveys to assess risk factors based on Severity (S), Occurrence (O), and Detection (D), which were quantified into Risk Priority Numbers (RPN). A 5x5 risk matrix was employed for visualization, and mitigation strategies were developed based on the highest RPN values. The most significant risks identified were: inadequate preheating in T-joints (RPN 158.33), poor inter-pass cleanliness in K-joints (RPN 308.00), and similar cleanliness issues in Y-joints (RPN 264.44). After implementing risk mitigation measures such as welder training and strict inter-pass cleaning procedures, the weld rejection rate was reduced to only 1.2% out of 998 joints. The application of FMEA proved effective in prioritizing and controlling welding risks. This structured risk management approach—aligned with ISO 31000:2018—contributed to improved weld quality and reliability in offshore wind farm construction.

Overview Biodiesel-hydrogen as a combined fuel resource in dual fuel diesel engine

Ahmad Khoirur Roziqi — 2025-12-05

Rising concerns about energy consumption and the environmental impact of fossil fuels are driving the search for alternative, cleaner energy sources. Extensive research has been conducted to explore alternative fuels as a means of optimizing energy requirements. This review provides a comprehensive analysis of how alternative fuels affect the combustion process in compression ignition (CI) engines, focusing on various combinations of diesel fuel with biodiesel, hydrogen, ammonia, LPG, and CNG. These fuels were combined to determine the most effective option. In the case of biodiesel-hydrogen mixtures, a 13-22% decrease in brake thermal efficiency (BTE) was observed. Conversely, using natural gas as an alternative fuel in dual-fuel engines resulted in a substantial increase in brake specific fuel consumption (BSFC), reaching up to 250 g/kWh.

Assessment of Engine Performance and Emissions Using Palm Oil–Banana Peel Biodiesel Blend in CI Engines

Suardi — 2025-12-05

The global need for renewable energy has encouraged the use of biodiesel from organic waste as an alternative to hydro-carbon fuels. This study focuses on evaluating the performance of a CI diesel engine using a fuel blend made from palm oil and banana peel oil. The objective is to determine the optimal blend in terms of fuel properties, engine performance, and exhaust emissions. The biodiesel is produced using the transesterification method for palm oil and a heating extraction process for banana peel oil. Engine tests are carried out on a Yanmar TF85-ME single-cylinder diesel engine using three fuel types: B0 (Dex-lite), BBO-30 (30% banana peel oil and biodiesel), and BBO-50 (50% blend). Fuel characterization showed that BBO-50 had the highest viscosity (4.23 cSt) and density (925 kg/m³), while BBO-30 had the highest calorific value (45.1 MJ/kg). Performance testing revealed that BBO-30 achieved the highest torque (7.26 Nm), lowest SFC (367.4 g/kWh), and highest thermal efficiency (22.4%). Emission tests showed that BBO-50 produced the lowest CO and NOx emissions, while BBO-30 had the highest CO₂ emis-sion, indicating more complete combustion. Based on these results, BBO-30 is recommended for optimal engine efficiency, while BBO-50 is more suitable for lower emissions.

Analysis of the Effectiveness of Agile Supply Chain in Indonesia’s Largest Shipbuilding Industry

Sutjipto — 2025-12-05

The shipbuilding industry is currently facing increasingly complex challenges, particularly related to market demand dynamics, global competition, and production timeliness. The implementation of Agile Supply Chain (ASC) is expected to be a strategic solution to address these challenges because ASC can increase flexibility and response to rapid changes and high demand variability. This study aims to analyze the Supply Chain Management (SCM) process in the largest shipbuilding industry in Indonesia, with a focus on identifying challenges in ASC implementation and examining the role of information technology in supporting this framework. A mixed methods approach is employed to investigate these issues by collecting data through questionnaires, in-depth interviews, direct observation, and analysis of relevant documents. The research findings indicate that ASC implementation, with collaboration and integration technology as the most dominant variables, can significantly improve operational flexibility, accelerate production timelines, reduce reliance on inventory, ensure timely material arrivals, and improve coordination among stakeholders in the supply chain. In addition, the adoption of ASC can result in faster ship construction compared to the initial planning stage. Challenges faced in implementing ASC include the need for investment in technological infrastructure, workforce training, and organizational culture transformation. Training, effective communication, and investment in supply chain digitalization systems are essential to improve the effectiveness of ASC implementation, thereby supporting the competitiveness and efficiency of the Indonesian shipbuilding industry in the future.

Sensitivity Study of Dynamic Response and Seismic Performance of Offshore Tripod Structure Under Variation of Center of Gravity Location

Novan Arif Hidayat — 2025-12-05

An effective weight control is critical for managing gravity loads and the center of gravity (CoG) evolution in offshore platforms. International standards, including ISO 19901-5:2021, require that CoG shift envelopes—defined in 2D (X–Y) and 3D (X–Y–Z) coordinate systems—be considered when assessing pile foundation capacity and global structural behavior. This study examines the sensitivity of the dynamic response and seismic performance of a three-legged fixed offshore structure (tripod) due to variation of CoG location. Tripod known have characteristic as slender structure and long natural period that make it particularly sensitive to gravity loads, lateral forces, and soil variability. A systematic sensitivity analysis was performed using 75 cases, spanning four directional quadrants in both 2D and 3D (upward and downward) associated with 0%, 10%, and 20% of topside operating mass increment. Dynamic and in-place analyses incorporating pile-soil interaction (PSI) were conducted using SACS software. Seismic performance was evaluated through response spectrum–based equivalent static methods. The results show variation of CoG location influenced the dynamic response and structural performance. The response determined significantly amplify if the CoG variation associated with mass increment, particularly under in-place conditions that exhibited greater sensitivity than seismic condition. The study also proposes a CoG shift envelope that maintains acceptable structural performance and recommends its adoption in future design and modification planning. Emphasis is placed on active CoG management and the necessity for future non-linear assessments to capture post-elastic behavior and ensure the robustness of tripod platform design.

Determining Tugboat Initial Speed Limit to Avoid Collision with Jetty at Paciran Port

Esqy Dhiya’ul Fuady — 2025-12-05

Paciran Port experiences growing vessel activity, particularly from limestone barges, highlighting the critical need for safe port operations. Ship berthing inherently carries risks, including potential collisions with the jetty. This study aims to determine the maximum safe initial speed limit for tugboats assisting barge berthing at Paciran Port, to prevent such incidents. We employed a simulation method based on the Maneuvering Modelling Group using MATLAB software. The MMG model considered various environmental factors, including water depth, wind forces, and current effects. The novelty of this paper lies in the integration of the CFD method and MMG to determine hull forces and moments. Hydrodynamic coefficients were obtained from Computational Fluid Dynamics (CFD) analysis and empirical formulas. Berthing speed acceptance criteria were based on PIANC standards. Our simulations, conducted across three environmental conditions and multiple initial speed variations, revealed that an initial speed of 5 knots resulted in "Unfavourable" berthing conditions, increasing collision risk. Conversely, initial speeds below 5 knots consistently allowed for safe berthing, with final speeds remaining below 0.3 m/s, meeting PIANC's Favourable to Moderate criteria. We conclude that the maximum acceptable initial tugboat speed at Paciran Port, to avoid jetty collisions during tugboat-assisted berthing, is below 4 knots.

Catch Per Unit Effort (CPUE) Dynamic of Scad (Decapterus spp) related to Water Parameters in the Banda Sea

Fajar Indah Ningsih — 2025-12-05

The lack of data and information concerning the scad fishing grounds in that area restricts the efficiency of fish capture. This research aims to estimate the CPUE of the scad, map the spatial-temporal dynamics of sea surface temperature (SST) and chlorophyll a (Chl-a), and evaluate the SST and Chl-a relationship to scad catch rates in the Banda Sea. The SST and chl-a were obtained from Aqua MODIS satellite imagery over three years (2020-2022), while scad catch data were obtained from the Kendari Fishing Port. Bivariate correlation analysis was used to assess the relationship between SST, Chl-a, and scad catch rates. The results show a fluctuation trend in CPUE (2020-2022), with CPUE values ranging from 53.41 to 354.65kg/trip. The temporal distribution of SST values ranged from 26.91 to 29.42°C, while the Chl-a concentration ranged from 0.20 to 4.8mg/m³. Spatially, it was higher near the shore and lower offshore. A moderate negative correlation (r = -0.464) was observed between Chl-a and CPUE, while SST showed a weak positive correlation (r = 0.101) with the CPUE. This study recommends integrating field data and satellite imagery to accurately estimate the fishing grounds to improve efficiency and sustainable fisheries management in the Banda Sea.

Effect of Biomass Waste and CaO Blend Compositions on the Pelletizing Characteristics of Refuse-Derived Fuel (RDF)

Lusi Ernawati — 2025-12-05

Refuse-Derived Fuel (RDF) is increasingly acknowledged as a sustainable method of managing municipal solid waste while simultaneously producing valuable energy. However, the quality and compactness of RDF as a fuel can vary substantially depending on the materials used to produce it. The incorporation of biomass waste and calcium oxide (CaO) significantly influences the pelletizing behavior of biopellets by altering their physical and thermal properties, which in turn determines their effectiveness and suitability as a fuel source. In this study, representative RDF pellets were prepared by blending four primary components: wood sawdust, organic waste, plastic waste, and a fixed proportion of CaO. The investigation focused on assessing the effects of varying biomass waste-to-organic waste ratios on the physicochemical characteristics, densification behavior, and proximate properties of typical RDF pellets. The experimental design included biomass-to-organic waste ratios of 1:1, 2:1, 3:1, 4:1, 5:1, and 6:1 while the proportions of plastic (20 wt%) and CaO (5 wt%) were held constant. The findings revealed that optimal RDF performance was achieved at biomass-to-organic waste ratios of 1:1 and 6:1, respectively. The resulting RDF pellets exhibited the following properties: ash content of 7.04 ± 8.78%, moisture content of 8.19 ± 8.82%, volatile matter ranging from 65.11 ± 66.19%, fixed carbon content of 13.95 ± 17.32%, calorific values between 4193 ± 4419 kcal·kg^-1, and bulk densities of 0.98 ± 1.18 kg·dm^-3. These results highlight the potential of RDF pellets as a promising alternative fuel source for boiler applications.

Structural Analysis and Design of Superstructure and Roof Systems for the Canteen Building at Kalimantan Institute of Technology

Hijriah — 2025-12-05

Kalimantan Institute of Technology (ITK), established on October 6, 2014, in Balikpapan, East Kalimantan, currently lacks adequate canteen facilities, compelling the academic community to seek meals off-campus. This study aims to design a new canteen facility to be constructed above the campus reservoir, focusing specifically on the structural and roofing systems. The planned canteen is expected to fulfill the food and beverage needs of students, lecturers, and staff, while also serving as a hub for social interaction. Our research methodology incorporates both qualitative and quantitative approaches. The project phases encompass detailed load analysis, structural modeling, internal force analysis, and a thorough plumbing design. Structural design adheres to the relevant Indonesian National Standards (SNI) for reinforced concrete structures and earthquake resistance. The substructure utilizes deep foundations adapted to local soil conditions, while the superstructure comprises reinforced concrete elements and a steel roofing system. Structural analysis results indicate the use of beams B1 (500×300 mm) and B2 (400×200 mm), circular columns K1 (D600 mm), and slab thickness of 120 mm. The roof structure consists of IWF rafters (300×150×6.5×9 mm), HB columns (300×300×10×15 mm), and CNP 200–16. This integrated design demonstrates a feasible and sustainable approach to infrastructure development on water-saturated soils.

System Modeling of Predictive Maintenance for Engine Health Monitoring on Ship Auxiliary Engines Using Vibration Variables

Egas Wahyu Endrianto — 2025-12-05

This research presents a dynamic system modelling approach for predictive maintenance of ship auxiliary engines using vibration variables. The model integrates key mechanical components—piston, crankshaft, camshaft, valve train, and timing gear—based on the specifications of a Yanmar TF85 diesel engine. Each subsystem is modelled using a multi-degree-of-freedom (MDOF) state-space framework to represent vibrational and structural dynamics. Simulations are carried out in MATLAB/Simulink under various engine operating conditions, including normal operation at high, medium, and low RPMs, as well as fault scenarios such as damping degradation in the piston and crankshaft. A fuzzy logic system is employed to interpret the vibration data and determine the impact level for each condition. The results indicate that under normal conditions, the engine maintains stable vibration levels, while faults lead to significant increases in velocity RMS values and impact severity. Disturbances in the piston result in dominant amplitude changes, while crankshaft faults affect the frequency propagation throughout the system. These findings confirm that the proposed model can effectively detect early mechanical deviations and support the implementation of predictive maintenance strategies for marine diesel engines.

The Influence of Safety Observation on the 9 Building Blocks of Safety Model Canvas for a Dredging Company

Muhammad Bilal Teguh — 2025-12-05

The dredging industry's dynamic and high-risk operational environment makes its safety culture a critical factor in preventing occupational accidents. However, the complex interplay between different dimensions of safety culture in such a unique, project-based context is not yet fully understood. This research aims to develop and empirically test a structural model that explains the causal relationships among the nine core dimensions of the Safety Model Canvas and evaluates the influence of Safety Observation program within this framework. This study employed a quantitative approach using Partial Least Square Structural Equation Modeling (SEM-PLS). Data were collected from a major Indonesian dredging company through 50-item questionnaires administered to 95 employees and an analysis of 595 formal Safety Observation reports. A model with 12 hypothesized paths was tested to validate the theoretical framework. The analysis confirmed the model's validity, with 8 of the 12 hypotheses being statistically significant. The findings reveal that the Safety Observation program significantly enhances both Engagement & Involvement and Information & Communication. A robust operational pathway was identified where proactive leadership fosters worker engagement, which in turn builds responsibility. However, the model also uncovered a critical systemic weakness in the organizational learning process, indicating a failure to effectively translate safety information into enhanced worker competence. This study contributes a validated causal model of safety culture, offering significant theoretical and practical insights for safety management in project-based maritime industries.

Optimizing Waste Management in Lhokseumawe City: a GIS-Based Needs Assessment for Collection Facilities to Mitigate Illegal Dumping

Nanda Savira Ersa — 2025-12-05

Solid waste management is a significant urban issue in Indonesia. This is exacerbated by rapid population growth and urbanization, which are not accompanied by sound waste management practices, such as a lack of infrastructure and widespread illegal dumping. This paper presents a data-driven methodology for analyzing trash generation patterns and identifying infrastructure requirements using a Geographic Information System (GIS). The goal is to create a data-driven strategy for identifying optimum Waste Collection Locations (WCPs) in order to improve service efficiency and reduce environmental impact. The study results show that Lhokseumawe City produces 530 m³ of waste daily. Therefore, Lhokseumawe City requires 44 strategically located waste disposal sites, taking into account existing illegal dumping locations and population density. An additional 21 garbage trucks are also needed to manage the urban waste generation volume. This indicates a significant shortage of waste management facilities to serve the population. This study presents a practical plan for local governments, including optimal WCP locations and designs, to achieve the SDGs goal of becoming a sustainable city.

Fatigue Analysis of Mid-Water Buoy (MWB) due to Changes in Pipeline End Manifold (PLEM) Position

Ibrahim Rahmatulloh — 2025-12-05

This research is a case study that will analyze the fatigue life of the Mid-Water Buoy (MWB) structure on the subsea hose string SPM #4 after the installation of New PLEM C, or in other words in conditions where the subsea hose string (including MWB) has been connected to New PLEM C. MWB is one of the ancillary components of the subsea hose string, which has the main function as a buoy to keep the entire subsea hose string at a safe distance to the seabed. By replacing the old PLEM-C with the New PLEM-C, the dynamic motion of the subsea hose when connected to the New PLEM-C will also be different compared to the dynamic motion when connected to the old PLEM-C. As the main input for fatigue analysis, cyclic load analysis acting on the MWB structure is carried out based on a deterministic approach through time domain simulation and continued with the calculation of the number of cycles with the rainflow cycle counting method. For local stress analysis in the critical area of the MWB structure, the hotspot stress method is carried out through the Finite Element Method (FEM) which refers to DNV-RP-C203. Furthermore, the fatigue life calculation is carried out by applying the Palmgren-Miner rules and by utilizing the S-N Curve from DNV-RP-C203. From a series of analyses that have been carried out it was found that the lowest fatigue life value for the MWB structure is occurs at PART B1 (the part of the MWB connected to the Subsea Hose STRING B – Upper) with a value of 145.93 years and with an annual damage ratio of 0.0069 for the Connection between the Vertical Stiffener and the Pipe.

Fatigue Analysis of Pipeline End Manifold (PLEM) due to Cyclic Load from Subsea Hoses

Rizal Arif Pratama — 2025-12-05

To ensure the continuity of delivering crude oil from the Central Plant to the Floating Storage and Offloading (FSO), PHE ONWJ plans to replace existing pipelines and Pipeline End Manifolds (PLEM) in order to enhance the integrity and reliability of the Marine Terminal facilities. The configuration changes resulting from the installation of new pipelines and PLEM alter the dynamic interactions between the subsea hoses connected to the New PLEM and Old PLEM, leading to different load conditions on the new PLEM structure. Considering the importance of PLEM in crude oil transfer process from wells within the ONWJ working area to the FSO, thus this research will conduct a fatigue analysis of the Pipeline End Manifold (PLEM) due to cyclic tension loads from subsea hoses. The objective of this research is to predict the fatigue life of New PLEM A structure by applying Palmgren-Miner Rule. The study will begin with an analysis of the mooring lines system and subsea hoses connected to the new PLEM to identify the cyclic tension loads acting on the structure. The analysis was performed using time domain simulation with output in the form of a tension time history. The results of the time tension history will then be processed to find the tension range cycle value using the Rainflow cycle counting method. Furthermore, to assess the stress distribution caused by cyclic loads from the subsea hoses, a local stress analysis will be performed using hotspot stress method by finite element analysis (FEA) which refers to DNV-RP-C203. The result of hotspot stress analysis will be used for the fatigue life calculation of the New PLEM A structure. The analysis results show that the lowest fatigue life of the new PLEM A structure occurs at the connection between pipe support and skid, with a fatigue life value of 17.63 years and a damage ratio of 0.0113. In contrast, the connection between the elbow pipe and flange exhibits a significantly higher fatigue life of 499.38 years and a damage ratio of 4 × 10^-4

CFD-Based Comparative Study of Axe Bow and Bulbous Bow Designs for Corvette Warship Deployment in Natuna Waters

Yeddid Yonatan Eka Darma — 2025-12-05

The Natuna Sea is considered a prime maritime area for Indonesia, bearing strategic and defense significance, besides its turbulent sea conditions demand warships to adopt or be provided with efficient and stable hull forms. Thus, this study is intended to investigate the most appropriate bow designs for a corvette warship operating in the Natuna region. Three types of bow are compared: a conventional V-hull, sloped bow, bulbous bow and axe bow. Comparison through Computational Fluid Dynamics (CFD) simulation, validated with Holtrop and Savitsky empirical methods, at the speed of 30 knots. Principal dimensions of the corvette were obtained through regression analysis from 20 other warships that belong to the same class. Results reveal that the axe bow has the smallest resistance, that is, 365.18 kN from Holtrop method and 374.27 kN from CFD in contrast to 384.43 kN owing to conventional bow design. It also fulfills all criteria of operation performance and fuel efficiency. Hence, it is considered the best alternative for corvette deployment into the Natuna Sea.

Direct Decarbonization Model for Handling Equipment at Jamrud Terminal Using a Combination Method of Default Emission Factors (DEF) and Direct Monitoring of Greenhouse Gas Emissions (DMGGE)

Sarwo Edy Agus Salim — 2025-12-05

As one of the largest archipelagic countries with a port system that supports more than 90% of its trade volume, Indonesia faces an urgent need to implement the green port concept to minimize environmental impacts, improve energy efficiency, and support national decarbonization commitments. One example is the Tanjung Perak Port, specifically
the Jamrud Terminal in Surabaya. This study takes Jamrud Terminal—which provides loading and unloading services for general cargo, passengers, and dry bulk—as a case study. The terminal operates 24 hours a day and thus undoubtedly contributes to pollution, including air pollution from exhaust gas emissions, which are increasing due to a 23.06% growth in
vehicle handling activities throughout 2024. Quantifying greenhouse gas (GHG) emissions from the main quay equipment and supporting equipment at Jamrud Terminal is crucial to assess current fossil fuel energy consumption and propose technological interventions to enhance energy efficiency and reduce GHG intensity from fuel usage.This paper aims to identify and calculate the existing direct emissions, analyze the trend of GHG emissions from port equipment, and develop a projection model of GHG emissions from equipment at Jamrud Terminal. The equipment includes Harbour Mobile Cranes, Harbour Portal Cranes, Excavators, Forklifts, Mobile Sweepers, Wheel Loaders, and Generators, with data sourced from primary records of fuel consumption supplied during the 2022 to 2024 period. GHG emissions projection is modeled using the Default Emission Factors method and the Direct Monitoring of Greenhouse Gas Emissions (DMGGE) approach. The results show that from 2022 to 2024, Jamrud Terminal emitted approximately 7.1 tons of CO₂eq from stationary combustion and 5,378.88 tons of CO₂eq from mobile combustion.A future decarbonization scenario developed in this study indicates that if the terminal transitions to electrification and the use of alternative energy fuels such as LPG or CNG, CO₂emissions could be reduced by as much as 98.6%. The results of this paper will be valuable in formulating effective planning, policies, and strategies to reduce GHG emissions from direct sources related to both main and supporting equipment at Jamrud Terminal.

Analysis of Oil Leaking from Bowl on The LO Purifier Alfa Laval P626 at MV. SEAPEAK GLASGOW LNGC

Bagas Putra Darmawan — 2025-12-05

Lubrication oil purifiers are essential for the optimal performance and longevity of marine engines. On board the MV. SEAPEAK GLASGOW, we encountered an issue with the Alfa Laval purifier, where alarm A57 indicated an oil leak from the bowl, accompanied by a drop in PT4 pressure and reduced bowl speed. This investigation aimed to identify the root causes of the leakage and recommend maintenance strategies to prevent future occurences. Using a qualitative approach, we conducted onboard observations, interviews with the third engineer, and a review of maintenance records. A fishbone diagram analysis revealed several contributing factors, including wear on the water block filter, scale buildup on internal components, and a lack of understanding of maintenance procedures among the engineering staff. The findings underscored that neglecting structured maintenance schedules and inadequate routine monitoring resulted in system inefficiency. As a corrective measure, an auxiliary filtration system was installed to protect and reduce scale accumulation. To further mitigate these issues, we recommend aligning maintenance activities with the purifier’s running hours and increasing the frequency of pressure checks. These actions will help minimise the risk of oil leaks and ensure consistent performance.

The Influence of Safety in Design Implementation on Construction Safety Performance in Building Projects

Enos Frendly Lase — 2025-12-05

The construction industry is one of the sectors with the highest occupational accident rates, particularly during the project execution phase. To address this issue, the concept of Safety in Design (SiD) has been introduced as a proactive approach to integrate hazard identification and risk mitigation into the design phase of construction projects. This study aims to analyze the influence of Safety in Design implementation on improving construction safety performance in building projects within DKI Jakarta. The research employs a quantitative method using a survey approach with 50 respondents representing project management roles from four high-rise building projects managed by a state-owned enterprise. The variables evaluated in this study include human/engineer factors, management aspects, and compliance and technology systems. Data were analyzed using ordinal logistic regression with several statistical tests, such as the Wald test, goodness-of-fit test, and test of parallel lines. The findings indicate that all SiD-related factors significantly contribute to enhancing construction safety performance. Among these, the management aspect exhibits the most dominant effect, followed by technology and compliance, and human factors. The model demonstrates good fit and validity, confirming the relevance of incorporating safety considerations at the early project planning stage. These results highlight the strategic importance of empowering designers and project managers with safety-oriented knowledge and integrating risk-based decision-making in the design process to reduce occupational accidents and improve safety outcomes in the field

Design And Construction of a Mobile Dust Catch Using Wet Scrubber Technology in a Wood Factory

Achmad Hilal Rusydi — 2025-12-05

The wood processing industry is a significant source of airborne dust emissions and wastewater, both of which can pose serious environmental and health hazards if not properly managed. This study aims to evaluate the performance of a mobile dust collection system utilizing wet scrubber technology at two primary operational points—cutting and sanding—while also assessing the effectiveness of treating dust-laden wastewater using electrocoagulation. The system was designed with a 55-liter tank and equipped with eight electrode plates (four aluminum and four iron) measuring 20 × 25 cm, providing a total effective area of 0.8 m². Experimental results demonstrated that the initial Total Suspended Solids (TSS) concentration of 440 mg/L was reduced to 250.55 mg/L after electrocoagulation, and further to 189.45 mg/L after filtration. Additionally, the addition of 200 mg/L of Poly Aluminium Chloride (PAC) reduced TSS from 320 mg/L to 40 mg/L, achieving an 87.5% removal efficiency. Field tests showed that the system successfully reduced airborne particle concentrations by 69.6% in the cutting area and 26.24% in the sanding area. These findings indicate that the proposed mobile wet scrubber system is effective in reducing both airborne dust and TSS levels in wastewater, making it a viable solution for dust control in wood processing industries.

Influence of Velocity on Hydrodynamic Flow Characteristics around Subsea Pipelines: A Numerical Analysis

Luh Putri Adnyani — 2025-12-05

This study investigates the influence of flow velocity on hydrodynamic flow characteristics around free-span subsea pipelines using computational fluid dynamics (CFD). Simulations were conducted at flow velocities of 1.1 m/s, 2.5 m/s, and 3.0 m/s to examine changes in mean flow field, bed shear stress, pressure distribution, and wake development. Results show that increasing velocity transitions the wake from stable laminar to turbulent with fully developed vortex streets, intensifying vortex shedding, wake asymmetry, and unsteady forces. Higher velocities significantly amplify peak bed shear stress, adverse pressure gradients, and the depth of velocity deficits, leading to prolonged wake recovery and increased turbulence. These effects have critical implications for vortex-induced vibration (VIV), hydrodynamic loading, and scour potential, emphasizing the need to consider velocity variation in the design and integrity assessment of subsea pipelines.

Numerical Study of Fillet Effects on Cavitation Development in Double Contraction Pipes

Ridwan Daris Naufal — 2025-12-05

This study investigates the effects of fillet geometry on cavitation development in series pipe systems with double sudden contraction using numerical simulations. The research evaluates how variations in fillet radius at contraction joints and inlet flow rate affect pressure distribution and cavitation characteristics. Three pipes with diameters of D, 0.6D, and 0.4D were arranged in series, with flow rates ranging from 500 to 3000 l/min. Simulations were conducted using ANSYS Fluent with the k-E turbulence model and Zwart-Gerber-Belamri cavitation model to predict vapor volume fraction and cavitation potential. Mesh independence verification ensured simulation accuracy. Results showed that the first contraction presented minimal cavitation risk, with cavitation number values above 0.5 across all conditions, while the second contraction showed significant cavitation, especially at higher flow rates. Increasing the fillet radius elevated local minimum pressure, reduced peak vapor fraction, and shortened the cavitation zone. Fillets helped smooth velocity gradients and reduce flow separation, lowering cavitation likelihood. These findings highlight the importance of geometric modification in minimizing cavitation and improving system durability. The study provides useful insights for designing more resilient industrial piping systems under high-flow conditions by combining flow control strategies and joint geometry optimization.

Bibliometric Analysis: Collaboration to Optimize Service Capacity to Inland Areas and Logistics Cost Efficiency Through Bundling Strategies and Inter-Port Cooperation

Faris Nofandi — 2025-12-05

Optimizing logistics costs and service capacity is a critical focus in modern supply chain management, particularly for connecting ports to inland "hinterland" areas. This paper investigates how inter-port cooperation, strategic service bundling, and enhanced connectivity can improve logistics cost efficiency in these regions. The methodology combines an in-depth literature review with a bibliometric analysis using VOSviewer and Publish or Perish software. The literature review focuses on five key dimensions: hinterland connectivity, inter-port cooperation, cost efficiency, bundling strategies, and service improvement. The findings indicate that a strategic combination of inter-port collaboration and logistics service bundling significantly enhances logistics cost efficiency in the hinterland region. The bibliometric analysis also identifies key research clusters and highlights opportunities for future studies, particularly in under-researched regions like Indonesia, where green port implementation is underway. These findings have important implications for managers and policymakers in developing collaborative strategies to improve supply chain performance. The study concludes by proposing several hypotheses for future research concerning transportation costs, user priorities, and the performance of collaboration models.

Analysis and Risk Mitigation Strategies for Occupational Accidents in Construction Activities at PT PP Site Development, Nickel Mining Area of PT X Using the HIRADC–Fuzzy TOPSIS Method

Muhammad Hafiz Aulia — 2025-12-05

This study aims to identify potential hazards and establish priority risk control strategies in nickel mining operations using the Hazard Identification, Risk Assessment, and Determining Control (HIRADC) method combined with the Fuzzy Technique for Order Preference by Similarity to Ideal Solution (Fuzzy TOPSIS) approach. The HIRADC analysis revealed several activities with high risk levels, including girder lifting, material/piping unloading, maintenance lifting, stone crushing, civil works, cathodic installation, and material loading/unloading operations. The most significant hazards identified were falling or being struck by objects, falls from heights, electrical shock, collisions with heavy equipment, and entrapment by materials. Five hazards were classified as very high risk, including falling objects (score 25), while falls from heights, electrical shock, collisions, and entrapment each scored 20. To determine mitigation priorities, the Fuzzy TOPSIS method was applied, resulting in recommended risk control strategies. The top-ranked strategies include ensuring areas are clear of falling objects and verifying lifting equipment capacity (C1), providing lifelines and full-body harnesses (C2), installing standard-compliant electrical panels with grounding (C3), segregating pedestrian pathways from heavy equipment routes (C4), and installing emergency stops and machine guards (C5). The findings demonstrate that integrating HIRADC with Fuzzy TOPSIS offers a systematic approach for effective risk management in nickel mining operations.

Keywords - HIRADC, Fuzzy TOPSIS, Hazard Identification, Risk Mitigation Startegy

Enhancing Material Efficiency in Ship Production: A Taguchi Method Approach to Optimal Plate Nesting

Eko Prayetno — 2025-12-05

This study seeks to enhance material use efficiency in plate nesting procedures for tugboat production through the application of the Taguchi method. Three critical criteria were assessed: plate profile dimensions, cutting margin, and number of parts, aimed at reducing material waste in steel plate cutting processes. Numerical simulations were performed with ProNest software, and the nesting output data were examined using Minitab to ascertain the ideal design via the Smaller-the-Better methodology. Experimental findings indicate that the ideal parameter configuration was attained with a plate profile dimension of 508 mm, a cutting margin of 10 mm, and a production quantity of 95 units. This setup resulted in little material waste, demonstrated by a maximum Signal-to-Noise Ratio (SNR) value of -49.17 dB, which is nearly zero. These findings indicate that this parameter combination can serve as a benchmark in production processes to improve material efficiency and minimize waste in tugboat fabrication.

Development of Fire and Temperature Monitoring Interface in The Engine Room Using Visual Basic Programming

Cahya Kusuma — 2025-12-05

The design of the Temperature and Fire Monitoring Interface using Visual Basic Programming aims to detect fires at any time on the ship, especially in the main engine and diesel generator rooms. If the ship's initial conditions in the Main Engine room and diesel generator room are created to cause a fire, the tool will send a fire hazard signal which can be directly monitored by the ship's crew so that prevention can be carried out as early as possible. This design uses two smoke sensors and temperature sensors as inputs, one Arduino Uno microcontroller as a controller, one PC / Laptop as an interface for monitoring temperature and smoke conditions. The result of this system is that if the input temperature sensor and smoke sensor do not detect a fire hazard, the interface output displays a green color. If the temperature and smoke sensor input detects a fire hazard, the interface output will print red, and the buzzer output will light up as set by a visual basic program.

Development A Fire Extinguisher Nozzle Drive Mechanism with Android Monitoring and Control

Cahya Kusuma — 2025-12-05

The warehouses on land are rooms that are prone to fire hazards. The Spare Parts warehouse contains engine spare parts, rubber lifeboats, ship paint, thinner, maritime equipment, lubricating oil, dry food, and other logistics support. These materials have a high level of vulnerability to fire hazards. Thus, the danger of fire is one of the potential threats that can occur in Dismatbek. A fire protection system is needed that can minimize losses due to fire. This research is intended to develop a design for a fire extinguisher nozzle drive mechanism with Android monitoring and control. By building a mechanical movement mechanism for the nozzle in the vertical and horizontal directions so that the focus can be directed to the fire source with the Esp 32 Microcontroller. There is a monitoring and control unit via an Android smartphone which is equipped with three sensors, namely fire, temperature, and smoke sensors which are connected to an Arduino microcontroller to identify fire hazards. From the overall test results, it was found that the nozzle was successful in moving vertically and horizontally with a good mechanism for driving the fire nozzle arm in transmitting the power distributed to the nozzle arm resulting in a gear ratio of 2.06: 1 with a final rotational speed of 3.8 rpm at In the elevation direction, the torque is 1,606 Nm and in the azimuth direction, the speed is 7.28 rpm, the final torque is 3,028 Nm. The fire nozzle monitoring and control unit is capable of detecting potential fire hazards and the nozzle can be controlled with an Android smartphone and can extinguish fires by spraying water at the source of the fire well.

Risk Level Assessment of Pre-Organization of Football Events with Information Technology-Based Likelihood and Severity Analysis Approach

Toni Bagus Murdjayanto — 2025-12-05

One of the most popular sports events in Indonesia is football. In running high-tension football matches, safety and security factors are of utmost importance. There are many potential risks in a football match that could endanger the safety of spectators, players, officials, and event organizers, such as the risk of riots. This study aims to analyze the inherent risks affecting the pre-event stage of a football match at the Gelora Bung Tomo Stadium, Surabaya. Additionally, this research analyzes and determines the risk assessment at the pre-event stage in terms of human, environmental, operational, and financial aspects using Likelihood and Severity analysis. The outcome of this research is the development of a risk assessment information system by implementing Crowd Risk Mitigation Technologies (CRMT) to support more effective and predictive risk management. The data and information processing is based on variables and indicators that affect the potential occurrence of an event (likelihood) and the adverse impact if the event occurs (severity). Indicators are assigned weighted values according to the event scale, such as low, medium, and high risks, resulting in a Risk Matrix. The risk value results will be implemented in the Crowd Risk Mitigation Technologies (CRMT) application program, which serves as a tool to facilitate the initial mapping of the pre-event conditions for a football match. This study aims to analyze Inherent Risk at the pre-event stage of a football match at Gelora Bung Tomo Stadium. The analysis process uses likelihood and severity approaches to assess the probability and impact, resulting in a Risk Matrix. The findings show that human risk has the highest relative risk index (77.5%), related to potential conflicts and violations, environmental risks have a relative risk index of 16.3%, indicating risks of facility damage, and operational risks have a relative risk index of 6.4%, indicating dominant risks related to system failures and coordination issues. The potential financial loss reaches 1.53 billion Rupiah (very high level), with the largest contribution from human risks (888 million Rupiah), followed by operational (375 million Rupiah) and environmental risks (250 million Rupiah). With a structured and cross-data approach, the Crowd Risk Mitigation Technologies (CRMT) application is implemented as a tool for assessing pre-event football risks.

Design of Planetary Gear for Vertical Axis Marine Current Turbine

Achmad Baidowi — 2025-12-05

Indonesia as the archipelagic country in the world offers an abundant resource of ocean energy and one of them is marine current energy. One of the key concept of designing marine current energy converter is the gearbox. This paper discusses the design of gearbox using planetary gear to transmit power from 27RPM current turbine to a 5kW generator with 200RPM and 269Nm input torque. This paper presented the comparison of single stage planetary gear and double stage planetary gear from the aspect of maximum stress and the weight design. From the aspect the maximum stress, both of the gear design still under the limitation of the material stress, while based on the weight perspective the single stage has lower weight compared to double stage of planetary gear but from the size perspective the single stage has a larger diameter compared to the double stage planetary gear.

Response of Traditional Boat to Ocean Waves in Operational Conditions

Sapto Wiratno Satoto — 2025-12-05

Traditional boats haves played a significant role in maritime activities such as fishing, transportation, and trade, particularly in Kepulauan Riau. These boats are typically constructed from wood, with hull designs passed down through generations. However, this traditional approach raises potential safety concerns due to the absence of standardized construction practices and compliance with maritime safety regulations. Reports of frequent accidents suggest that human factors and inadequate hull responses to wave conditions are contributing causes. This study aims to analyze the response of traditional boats from Riau Islands using numerical simulation methods. The analysis is conducted using Maxsurf software, particularly Maxsurf Motions and Maxsurf Stability, applying the linear wave theory approach to evaluate pitch, roll, and heave responses under variations in loading, speed, and wave direction. The results indicate that the boat’s intact stability and seakeeping performance meet IMO safety criteria (C1–C6) under both stationary and 6-knot speed conditions. The seakeeping evaluation conducted using Olson’s criteria under wave height variations ranging from 0.5 to 1.0 meters demonstrates that the vessel’s response consistently remains below the maximum permissible threshold. This research provides initial data and insights to better understand the intact stability and seakeeping characteristics of traditional boats in Riau Islands, particularly regarding their wave response behavior.

Analysis of Business Uncertainty in The Reefer Container Sector in The Vuca Era of Industry 4.0 (Case Study of Shipping Company Domestic Route)

Hadi Winoto — 2025-12-05

This study examines the phenomenon of uncertainty in the reefer container business within the VUCA era (Volatility, Uncertainty, Complexity, Ambiguity), focusing on a domestic route case study of Shipping Company. The background of this research lies in the demand for fresh product delivery, which faces uncertainties in market conditions. The objective of the study is to identify the factors of uncertainty, classify their impacts based on relevant divisions, and provide mitigation solutions. The research methodology employed is a qualitative case study, involving observations, questionnaires, and documentation. The findings reveal that uncertainties stem from government policies, delays in vessel schedules, and fluctuations in operational costs such as fuel prices and freight tariffs. The study concludes that cross-division collaboration and improved mitigation strategies are crucial to maintaining business stability. It is recommended that Shipping Company enhance employee training, strengthen technology integration, and establish strategic partnerships with logistics partners to minimize the impact of uncertainties.

Design of water Ambulance for Improving Healthcare Services in Mahakam Ulu Regency

Chris Jeremy Verian Sitorus — 2025-12-05

Mahakam Ulu Regency's landscape is dominated by tropical rainforest, with transportation access heavily reliant on river routes. The region is home to 245 rivers, ten of which are classified as major rivers and are distributed across all sub-districts. The Mahakam River serves as the main artery for community activities, including the emergency transport of patients. Nevertheless, serious challenges persist due to limited healthcare infrastructure and inadequate medical transport, which hinder the timely treatment of patients. Currently, there are no water ambulances specifically designed for emergency medical services, leading to delays and increased risks of patient morbidity and mortality.The aim of this study is to develop a water ambulance vessel designed to serve as a dedicated river based medical transport in Mahakam Ulu. A parent ship design approach was applied in the development process. The principal dimensions defined in this study are as follows:Length Overall (LOA): 10.5 m,Beam (B): 3.15 m, Depth (H): 1.35 m, Draft (T): 0.65 m, Service Speed (Vs): 20 knots, Accommodation: 10 crew and passengers.

Keywords- Mahakam Ulu, Mahakam River, Water Ambulance, Parent Ship Design

Structural Response Analysis During Slamming Events on Speedboats Using Aluminum Material

Amalia Ika Wulandari — 2025-12-05

The structural response analysis of an aluminum speedboat during slam-ming due to regular waves was conducted using the one-way fluid-structure interaction method. This method involves generating waves through hydrody-namic diffraction to obtain loads, which are then applied to the ship's struc-ture and analyzed using finite element analysis. It is known that the greater the force generated from slamming , the stress and deformation at the critical load point will increase. In addition to being influenced by the critical point, the maximum stress is also influenced by the ship's construction design. It has been found that the highest stress and deformation occur on the surface of the plate that is not supported by the transverse construction. Therefore, it can be concluded that the construction design can influence the magnitude of the structural response to the slamming event . Efforts that can be made by ship designers and manufacturers are to convert ships by using materials that are better at absorbing loads, such as the use of sandwich materials

Fuel Saving Model on Seine Net Boats in Palabuhanratu

Dwi Putra Yuwandana — 2025-12-05

Fuel oil is a critical input for seine net fishing in Palabuhanratu, yet its rising cost imposes a heavy burden on fishers and boat owners. Although fishers intuitively adjust engine power to reduce fuel use, the effectiveness of these practices remains unclear due to limited data. This study examines fuel consumption patterns of seine net boats and explores potential savings strategies. Data were collected on daily fuel use, vessel speed, trip duration, and operating distances across boats with engines of different ages. Results show that fishing trips follow eight distinct phases: preparation, outbound steaming, setting, hauling, fish hunting, resting, inbound steaming, and berthing. The highest fuel use occurs during fish hunting as well as outbound and inbound steaming, where high speeds and long durations dominate. Engine age strongly influences efficiency: a 6-month-old engine achieved a specific fuel consumption (SFC) of 328.42 g/kWh, compared to 499.33 g/kWh for a 7-year-old and 873.41 g/kWh for a 12-year-old engine. Simulation of reduced speeds during fuel-intensive phases suggests potential savings of 1.7%–21.7%, without compromising operational feasibility. These findings highlight the importance of managing vessel speed and engine condition to optimize fuel efficiency in seine net fisheries.

Automatic Identification System (AIS) Data Reliability and Its Implications for Maritime Safety in Indonesia

Mohammad Danil Arifin — 2025-12-05

The Automatic Identification System (AIS) is central to vessel monitoring, traffic management, and maritime safety, yet concerns remain regarding its reliability due to incomplete, inaccurate, or delayed reporting. This study assesses AIS data from the Indonesian maritime domain, focusing on four parameters: completeness, accuracy, consistency, and timeliness. AIS records data were preprocessed through data cleaning, filtering, and detection of missing values in static fields such as draught, beam, LOA, deadweight, and gross tonnage (GT). Statistical and spatial-temporal analyses using Python were applied to quantify missing data, identify anomalies, and evaluate reporting intervals. Results show high completeness (97.5%), although missing draught data (6.77%) limited under-keel clearance assessments, while small gaps in beam and LOA affected collision risk modeling and berth allocation. Accuracy was moderate, with invalid speed and course records observed, whereas consistency was excellent, with MMSI and ship names fully aligned. Timeliness proved weakest, with median reporting intervals (8,380 seconds) exceeding IMO standards, restricting real-time navigational use but remaining suitable for long-term monitoring. Overall, AIS in Indonesia is reliable for strategic traffic analysis but insufficient for operational safety management. Strengthening reporting compliance, integrating port and registry databases, and applying anomaly detection and satellite AIS are recommended to enhance maritime safety.

A Critical Review of Performance Improvement Techniques in Compression Ignition Engines

Elwas Cahya Wahyu Pribadi — 2025-12-05

Compression ignition engines play a critical role in various industrial and transportation applications; however, their environmental impact remains a major concern. Continuous research efforts have been directed toward optimizing engine performance to enhance efficiency and reduce emissions. This paper reviews key strategies that have been investigated for performance optimization, primarily focusing on combustion chamber geometry, fuel properties, and advanced combustion modes. Each of these factors significantly influences the combustion process, thereby affecting engine performance and emission characteristics. While no single method has proven sufficient to fully resolve all challenges associated with these engines, combustion chamber geometry optimization has demonstrated potential in improving efficiency and reducing pollutant emissions. More notably, integrating multiple optimization techniques appears to offer a more effective pathway toward achieving substantial improvements in overall engine performance.

Ergonomic Analysis of Welding Postures on Productivity and Weld Quality Using the REBA Method

Yoseph Arya Dewanto — 2025-12-05

Ergonomics in the workplace plays a vital role in reducing the risk of musculoskeletal disorders, preventing accidents, and improving both work efficiency and productivity. In shipbuilding welding activities, workers are frequently exposed to awkward and static postures that lead to fatigue, stress, and long-term injuries, which may compromise weld quality and project performance. This study aims to analyze ergonomic risks across four welding postures i.e., downhand, vertical, horizontal, and overhead, using the Rapid Entire Body Assessment (REBA) and Nordic Body Map (NBM) methods. The REBA assessment indicated that downhand welding scored 10 (high risk), vertical welding 11 (very high risk), horizontal welding 8 (high risk), and overhead welding 9 (high risk). NBM results revealed that 77.5% of welders in vertical welding reported waist pain, 72.5% calf pain, and 70% back pain; horizontal welding showed 67.5% right-hand pain and 65% right-wrist pain; overhead welding resulted in 57.5% neck and waist pain; while downhand welding still caused 70% complaints in the back and calves. These findings confirm that welding ergonomics directly affect worker health, weld quality, and productivity. The study recommends ergonomic interventions such as scaffolding, adjustable supports, arm rests, and proper work rotation to minimize strain, enhance safety, and ensure efficiency in shipyard operations.

Smart Aquaculture under Digital Transformation: AHP Approach for Optimizing Vannamei Shrimp Farming in Central Java

Soni Adiyono — 2025-12-05

The transformation of aquaculture through digital technologies has become increasingly essential to enhance sustainability, efficiency, and competitiveness in shrimp farming. Despite its importance, the challenge of determining which regions should be prioritized for digital adoption remains unresolved, particularly in contexts with diverse production and economic conditions. This study introduces the Analytical Hierarchy Process (AHP) as a multi-criteria decision-making tool to evaluate and prioritize coastal districts in Central Java, Indonesia, for smart aquaculture development in Litopenaeus vannamei farming. AHP integrates indicators of production potential, economic feasibility, and price competitiveness into a unified ranking framework, producing clear differentiation across districts. The results highlight Cilacap, Kendal, Brebes, Purworejo, and Rembang as priority areas for early adoption of digital innovations such as IoT-based monitoring, AI-driven disease prediction, and traceability platforms. This research contributes to the operationalization of the AHP algorithm for aquaculture decision-making, contextualization of the global digital transformation framework in the Indonesian shrimp sector, and demonstrates the robustness of multi-criteria prioritization for policy planning. Although the precision of the results may be limited by the scope of the available data, the study confirms the significant role of AHP in guiding evidence-based, scalable, and adaptive strategies for advancing smart aquaculture.

Experimental Study of Turbine Mechanism Using Cantilever PVDF Piezoelectric with Current Power on a Laboratory Scale

Ede Mehta Wardana — 2025-12-05

This research explores the integration of Internet of Things (IoT) technology with MEMS (Micro Electro Mechanical Systems) sensors and piezoelectric technology to enhance the efficiency and operational sustainability of devices. IoT connects physical devices to the internet to collect and exchange information and has become an integral part of Industry 4.0. The main components of IoT include physical objects, communication channels, software, operations, and data. In this study, IoT development focuses on the maritime sector with the application of MEMS sensors, piezoelectric technology, ocean current speed, and turbines. The use of piezoelectric technology allows devices to operate autonomously by harvesting energy from vibrations and pressure, further improving the efficiency of IoT devices. Experimental results show that in an open circuit, the highest average voltage at a speed of 1.1 m/s reached 0.019606 mV (capacitor) and 0.0056 mV (non-capacitor). In a closed circuit, with one non-capacitor piezoelectric, the average voltage was 14.762 mV and the average current was 0.0027 mA, producing a power output of 0.0398 mW. With four non-capacitor piezoelectrics, the average voltage reached 33.174 mV and the current was 0.0044 mA, producing a power output of 0.0146 mW. Meanwhile, with one capacitor piezoelectric, the average voltage was 4.947 mV and the current was 0.0023 mA, producing a power output of 0.01138 mW. With four capacitor piezoelectrics, the average voltage was 16.627 mV and the current was 0.0036 mA, producing a power output of 0.05986 mW. These results indicate that the piezoelectric turbine mechanism has significant potential as a reference for the development of future renewable energy technologies. The implementation of this technology allows IoT and MEMS devices to function autonomously and sustainably, supporting applications in various sectors including maritime and industry.

Offshore Platform Leg Integrity Assessment in the Gulf of Guinea

Charles Ugochukwu Orji — 2025-12-05

Offshore platforms are large structures designed to accommodate personnel and equipment required for drilling wells in the seabed, extracting oil and/or natural gas, processing the resultant fluids, and transporting them to land by shipping or pipelines. Jacket platforms are fixed structures anchored to the seabed with piles to ensure stability against wind, wave, and current forces in the marine environment. The gradual deterioration of the fixed platform over time during operations becomes a subject of concern. The study aims to carry out a structural safety assessment (SSA) of an existing offshore platform in the Gulf of Guinea (GOG) by analyzing the reliability, risk index, safety margins, and structural integrity of the platform. A detailed investigation of design specifications, material characteristics, and environmental loads assessed the structural reliability and risk margins. A risk matrix prioritizes major structural concerns, resulting in specific recommendations for mitigation, repair, and maintenance. The platform's reserve strength ratio (RSR) was examined to build long-term structural integrity, safety, reliability, and environmental resilience strategies. The platform's safety and structural integrity were assessed using Ultimate Strength Assessment (USA) and Reliability–Risk Assessment (RRA) methods. According to the findings, corrosion, fatigue, seabed scour, subsidence, overload from environmental forces (wind, waves, currents, and earthquakes), collisions, crane accidents, explosions, falling objects, fires, leaks, accidental discharges, towing incidents, and well-related damage are the main threats to the jacket platform. The extent of corrosion and the associated probabilities of failure (POF) and reliability of the platform’s four jacket legs were calculated. The corrosion losses for Legs 1, 2, 3, and 4 were found to be 4.577%, 3.462%, 3.346%, and 4.039%, respectively. Leg 1 exhibited the highest POF (0.04577) and the lowest reliability (0.95423), whereas Leg 3 showed the lowest POF (0.03346) and the highest reliability (0.96654). The overall reliability factor of the platform was determined to be 1.0401, which, although lower than the safety load factor of 1.25, still indicates a level of structural safety. According to the risk matrix, all four jacket legs (L1–L4) fall within the “Medium” risk category for structural failure, suggesting the risk is within acceptable limits. To address corrosion-related risks specifically, cathodic protection is recommended as an effective mitigation and maintenance strategy. The Ultimate strength analysis produced an Ultimate strength of 3000 kN for a design capacity of 1250 kN, resulting in an RSR of 2.4, which is more than the minimum safety criterion of 1.50 for a manned structure, indicating that the jacket platform structure is SAFE and Fit-for-Purpose.

A Direct Measurement of Vibration on the HDPE Structure of POLBENG Research Boat

Muhammad Alimul Hafiz — 2025-12-05

The adoption of High Density Polyethylene (HDPE) as the primary material for boat structures has increased significantly in recent years. In response to contemporary challenges and to facilitate research requirements, Politeknik Negeri Bengkalis (POLBENG) constructed a research boat utilizing HDPE. Nevertheless, further research on the response of the HDPE structure to vibrations generated by the main propulsion engine remains insufficiently intensive. Therefore, a direct measurement of ship vibration is conducted utilizing vibration sensors, namely Witmotion WTVB02-485. Both inside and outside of the accommodation rooms, measurements were taken. By comparing the vibrational velocity's Root Mean Square (RMS) to standards established by the American Bureau of Shipping (ABS), a classification society, structural assessment was evaluated. Furthermore, resonance events were discovered by comparing the Blade Passing Frequency (BPF) with the recorded peak frequency output. The HDPE structure seems to be dependable, according to the measurement findings at both locations. The RMS of 0.020 mm/s and a peak frequency of 33.31 Hz were recorded inside the accommodation area, whereas 0.013 mm/s and 31.52 Hz were recorded outside.