다기준 의사결정 기법을 이용한 어업용 씨앵커 개선방안 연구

Abstract

Sea anchors for fishing operations are essential equipment used to control vessel drift and maintain hull stability. They perform multiple functions, including fish aggregation, enhanced fishing efficiency, and crew safety, across various fishing practices such as jigging vessel, large power purse seiner and (recreational) fishing boats. However, sea anchors have been designed and operated without standardized specifications, relying primarily on the experience of manufacturers and the customary practices of field users. Consequently, various issues have been repeatedly raised, including structural inefficiencies, material limitations, and operational inconveniences. In particular, amid growing challenges such as changing marine environments, an aging fishing workforce, and labor shortages, the demand from the field for improvements in the design and operation of fishing sea anchors is increasing significantly. This study was initiated in response to these challenges, aiming to derive practical and field-oriented improvement strategies for the design and operation of fishing sea anchors, and to empirically validate their effectiveness. Previous research on sea anchors has primarily focused on theoretical and technical aspects, such as structural configurations and hydrodynamic resistance, without sufficiently reflecting the diverse needs and operational characteristics of actual fishing environments. To address this gap, the present study adopts a bottom-up approach based on the experience of end-users and manufacturers, and integrates scientific methodology with real-sea trials to empirically examine potential improvements. First, a Multi-Criteria Decision-Making (MCDM) approach was employed to identify key areas for improvement based on expert perceptions. A panel of 25 experts was assembled, including captains of squid jigging vessels, captains of (recreational) fishing boats, sea anchor manufacturers, and experienced professionals from research and educational institutions. A three-round Delphi survey was conducted, through which a total of 52 potential improvement items were initially collected. These items were then refined through response analysis, validity screening, and consensus-building procedures, resulting in a final list of 15 improvement factors. Subsequently, the Analytic Hierarchy Process (AHP) was applied to evaluate the relative importance of each item. As a result, the top five priorities identified based on composite weights were enhancement of fabric drying performance (0.11970), application of low-cost·high-efficiency materials (0.09640), improvement of recovery (0.09610), enhancement of UV resistance (0.07792), and product quality certification (0.07388). Response reliability was confirmed through a consistency ratio (CR ≤ 0.1). In the subsequent experimental phase, the study focused on the top three improvement priorities: enhancement of drying performance, application of low-cost and high-efficiency materials, and improvement of recovery convenience. The analysis indicated that these factors were closely related to material characteristics, particularly the type of fabric used for the canopy of the sea anchor. It was determined that modifying the fabric material could provide an effective solution. However, it was essential to ensure that the deployment performance, which is the most critical function of a fishing sea anchor, would be maintained or improved. Based on this premise, the study experimentally examined the applicability of polyester (PES) as an alternative to the conventionally used polyamide (PA) fabric. To this end, various physical properties of PA and PES fabrics were evaluated, including apparent yarn count, mass per unit area, water absorption, drying rate, air permeability, and tensile strength under both dry and wet conditions. All tests were conducted in accordance with Korean Standards (KS). The experimental results showed that the PES fabric (Sample C) had the lowest mass per unit area at 150.8 g/m², which was approximately 16.1% lighter than the standard PA fabric (Sample A) and 28.4% lighter than the high-density PA fabric (Sample B). PES also exhibited the fastest drying rate at 50 minutes, the lowest water absorption (65 mm in the warp direction and 78 mm in the weft direction), and the highest air permeability at 26.3 mm/s. Regarding mechanical performance, the PA fabric (Sample A) showed an average tensile strength of approximately 2,500 N in both warp and weft directions under standard conditions, which decreased to about 2,100 N in wet conditions, indicating a 16% reduction in both directions. In contrast, the PES fabric (Sample C) maintained a tensile strength of approximately 2,000 N in both directions under standard conditions, and retained 1,900 N and 2,000 N in the warp and weft directions, respectively, in wet conditions, resulting in only a 5% decrease in the warp direction. The PES fabric also demonstrated lower elongation, providing better dimensional stability. This is advantageous for underwater applications, where mechanical stability under wet conditions is essential for sea anchor performance. These findings indicate that PES fabric can effectively compensate for the physical limitations of PA and serve as a practical and suitable alternative material for the canopy of sea anchors used in real-world marine operations. Based on the results obtained from the fabric property tests, sea trials were conducted to verify the field applicability of PES material. The experiments compared the drying performance, deployment performance (canopy entrance diameter), and acting tension of three types of sea anchors fabricated under identical design conditions: a PA-based sea anchor, a PES-based sea anchor, and a sea anchor with a canopy constructed with alternating PA and PES strips. In the drying performance test, after 120 minutes of seawater immersion, the PES sea anchor (Sample B) showed the lowest residual water content at 41.5 kg, which was significantly lower than that of the PA sea anchor (Sample A, 51.0 kg) and the sea anchor with a canopy constructed with alternating PA and PES strips (Sample C, 47.0 kg) (p < 0.05). The water reduction rate of the PES sea anchor was the highest at 43.2%, clearly demonstrating its superior drying performance. In the deployment performance test, the PES sea anchor achieved a canopy deployment diameter equal to or greater than that of the PA sea anchor, indicating that the key functional aspect of deployment performance was not compromised. Analysis of vent-hole diameter effects (40 cm, 80 cm) showed that, under the 80 cm condition, Sample B recorded an average deployed canopy diameter of 584.3 cm (standard deviation 12.77 cm), which was slightly higher than Sample A (572.8 cm). In contrast, reducing the vent-hole diameter to 40 cm resulted in a reduction of approximately 50 to 70 cm in deployment diameter and an increase in acting tension to 249–268 kgf. This confirmed that vent size had a greater influence on deployment performance than fabric material. These results provide empirical evidence that PES fabric can serve as an effective alternative in addressing the key improvement areas identified for the design and operation of sea anchors for fishing operations, namely enhancement of drying performance, application of low-cost and high-efficiency materials, and improvement of recovery convenience. PES fabric demonstrated excellent drying performance due to its low water absorption and fast drying rate. In addition, its lightweight nature and superior drainage capability contributed positively to the ease of retrieval. Furthermore, PES fabric did not compromise the core functional aspect of deployment performance and, compared to PA, offered both improved efficiency and durability, making it a practical material alternative in the context of applying low-cost and high-efficiency materials. This study aimed to go beyond simple equipment improvement by integrating theoretical validity with field-based empirical verification, through a demand-driven approach and experimental design grounded in actual fishing conditions. By doing so, it seeks to contribute meaningfully to the scientific design and performance advancement of sea anchors for fishing operations, ultimately enhancing operational efficiency and safety. In particular, the identification of improvement factors using multi-criteria decision-making methods offers a valuable foundation for the future development of design guidelines and standardization systems for sea anchors. Furthermore, by combining laboratory tests with full-scale sea trials, this research provides a comprehensive case of performance evaluation based on scientific design principles. The results of this study are expected to serve as a foundation for the development of technologies that are both practically applicable and field-validated. They may also contribute to future efforts in performance standardization, material diversification, and operational optimization, supporting sustainable development in the fisheries sector. Keywords: Sea anchor, Multi-criteria decision-making (MCDM), Delphi method, Analytic Hierarchy Process (AHP), Polyamide (PA), Polyester (PES), Korean Industrial standards (KS), Standardization