This applied mathematical study develops a linear-programming model for maritime speed allocation to minimize estimated voyage operating cost under route-distance and sailing-deadline constraints. The decision variables represent the distance assigned to each predefined speed mode, enabling the model to determine a continuous mixed-speed allocation that remains feasible within the permitted sailing time. The model was implemented in a web-based Intelligent Decision Support System (IDSS) using a HiGHS-based linear-programming solver and demonstrated on the Tanjung Priok–Tanjung Perak route using an application-generated distance of 469.84 nautical miles. Under a baseline VLSFO price of USD 755/MT and a 35-hour sailing deadline, the model allocated 390.69 NM to the 13-knot mode and 79.15 NM to the 16-knot mode, producing an estimated minimum operating cost of USD 34,748.16 and total fuel consumption of 38.30 MT. Sensitivity analysis shows that tighter deadlines shift the optimal allocation toward higher-speed modes, increase estimated voyage cost, and eventually produce infeasibility when the required travel time falls below the capability of the fastest available speed mode. At the fixed 35-hour deadline, fuel-price variation changes the objective-function value without altering the selected speed allocation in the tested scenarios. As a supplementary interpretive component, an LLM-based layer transforms structured optimization outputs into a natural-language Voyage Master Plan while preserving the ship master's final authority. The study therefore contributes a traceable mathematical optimization model and a functionally integrated explanation interface. Because the analysis uses model-input parameters rather than empirically calibrated vessel records and does not include user-based evaluation, further validation is required before operational deployment.
Technical disruptions causing unplanned ship downtime present a costly challenge for PT X. Although the International Safety Management (ISM) Code mandates a Planned Maintenance System (PMS), its practical effectiveness depends heavily on human and organizational factors—specifically crew technical competence and SOP compliance. This study aims to determine the priority weights of criteria influencing PMS effectiveness and identify strategic interventions to reduce fleet downtime. A mixed qualitative–quantitative approach based on Multi-Criteria Decision Making (MCDM), specifically the Analytic Hierarchy Process (AHP), was employed to construct a four-level decision hierarchy. Pairwise comparison data were gathered from 7–10 operational and managerial experts at PT X. Expert judgments were aggregated using the geometric mean method and validated through consistency ratio testing ($CR \le 0.10$) and Kendall's Coefficient of Concordance ($W \ge 0.70$). Robustness was further verified using One-at-a-Time (OAT) and threshold sensitivity analyses. The findings anticipate that Procedural and SOP Compliance will emerge as the most dominant criterion, closely followed by Crew Technical Competence. Among the strategic alternatives, PMS Digitalization and Periodic SOP Audits are projected as the top priorities. These results are contextualized against DNV Maritime Safety Trends data (2014–2024) to align PT X challenges with global industry patterns. Ultimately, this study provides PT X management with an evidence-based, weighted decision-support framework to optimize interventions and minimize operational fleet downtime.
Oil and gas transmission pipelines operating beyond their original design life require comprehensive integrity assessments to ensure safe, reliable, and sustainable continued operation. Life-extension decisions should not rely only on asset age but must consider actual degradation conditions, operational risks, structural integrity, and remaining service capability. This study proposes an integrated pipeline integrity assessment framework to support technical decision-making for aging transmission pipelines. The proposed framework combines Failure Mechanism Identification (FMI), Risk Assessment (RA), Fitness-for-Service (FFS), and Residual Life Assessment (RLA) into a structured evaluation process. The methodology was applied to a 10-inch API 5L X52 condensate transmission pipeline located in Jambi, Indonesia. Inspection records, ultrasonic thickness measurements, operational data, and engineering evaluation reports were analyzed to determine the actual integrity condition of the pipeline. The results showed that external corrosion was the dominant degradation mechanism affecting the pipeline system. Risk assessment indicated that most evaluated pipeline segments remained within acceptable risk levels. Fitness-for-Service evaluation confirmed that the pipeline satisfied the required acceptance criteria, with sufficient wall thickness for continued operation. Residual Life Assessment demonstrated adequate remaining service capability beyond the original design life. This study confirms that integrated integrity assessment provides a systematic and technically justified approach for supporting risk-based pipeline life-extension decisions.
Autonomous surface vehicles (ASVs) are increasingly deployed for hydrographic survey, coastal observation, and unmanned maritime monitoring. Although autonomous waypoint navigation enables an ASV to execute predefined missions, shore-side operators still require a supervision mechanism that can interpret navigation telemetry, identify route deviation tendencies, and provide timely operational alerts. This paper proposes a VTS-oriented route deviation monitoring framework for ASVs using waypoint-tracking telemetry and navigation alert classification. The proposed framework utilizes mission waypoints, actual GPS position, heading, speed, mission status, and communication streams to evaluate whether the vessel remains consistent with its planned navigation task. Instead of focusing on onboard control performance, the framework transforms waypoint error, heading deviation, and telemetry status into operator-oriented alert levels, namely normal, caution, warning, and danger. The framework is developed using datasets and system components from a catamaran-type ASV testbed supported by autonomous waypoint navigation, web-based telemetry transmission, and onboard logging infrastructure. The available navigation dataset consists of ten simulation trials and ten real-world trials, with baseline results showing a mean waypoint error of 0.49 m and mean heading error of 4.21° in simulation, and a mean waypoint error of 1.15 m and mean heading error of 10.8° under real-world operation. The monitoring infrastructure further supports real-time supervision through web-based telemetry and low-latency data transmission, with previous testing reporting a GPS positional error of 3.66 m, data fetch time of 199 ms, and data transmission time of 165 ms. In addition, mission logging data demonstrated a 618.0 s operational record with 100.0% file completeness and 99.81% multi-sensor continuity. These results indicate that the developed ASV testbed provides sufficient telemetry readiness for route deviation monitoring and shore-side navigation alert generation. Unlike previous studies that focus on waypoint control, communication performance, or onboard collision avoidance, this study positions route deviation monitoring as a VTS-relevant safety supervision layer for small and medium ASVs operating in restricted and coastal waters.
Climate change increases the vulnerability of fishing communities through weather uncertainty, changes in fishing seasons, declining catch yields, and household income instability. This study aims to formulate strategies to enhance the resilience of fishermen on Nias Island based on local culture in the face of climate change. The study employed a Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis based on internal and external factors affecting fishermen’s adaptive capacity. The analysis results show an IFAS score of 2.314 and an EFAS score of 2.120, with the strategy positioned in Quadrant I (aggressive). The primary strengths of Nias fishermen stem from their cultural values and seafaring traditions, as well as their local knowledge in understanding ocean conditions and seasons. Conversely, the main weaknesses lie in the low level of processing and value addition of fishery products, as well as the weak economic capacity of fishing households. The greatest opportunities stem from the potential of fishery resources and support from capacity-building programs, while the main threats include weather uncertainty, declining catch yields, and fluctuations in the prices of fishery products. The resulting strategies focus on strengthening adaptation based on local culture, increasing the value added of fishery products, strengthening institutions, and community-based management of coastal resources. These findings indicate that local culture and traditional ecological knowledge are key assets in enhancing the resilience of Nias fishermen to climate change.
