• Journal of the Society of Naval Architects of Korea
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• v.46 no.1
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• pp.10-23
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• 2009

Korean small coastal fishing boats have the different kind of fisheries and customs against Japanese fishing boats. Those bring some influences on the principal parameters of hull form. In same displacement, Korean small coastal fishing boat has generally shorter length, draft and wider breadth than Japanese fishing boat. Furthermore, even though the parameters of each hull form are similar, it is known that the resistance performance of Korean small coastal fishing boat is worse than that of Japanese fishing boat. In this study, the representative hull forms of Korean and Japanese small coastal fishing boats are selected and compared to evaluate the resistance performance of Korean fishing boat in low-speed range. The hull form of the Korean fishing boat is modified as comparison with that of the Japanese fishing boat to confirm the partial characteristic differences between the hull forms and the resistance performances. The representative partial characteristics of hull form are the gradient of chine line, keel shape and stern length. The resistance performances of the modified hull forms are evaluated by INHAWAVE which is one of CFD program and model tests in towing tank. The results of the present study will be used to improve the resistance performance and to develop the practical hull form of Korean small coastal fishing boats as principal data in the preliminary hull form design of fishing boats.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.35 no.3
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• pp.323-327
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• 1999

Most of the underwater noise emitted by small fishing boat are owing to vibration of main engine and generator etc.. This paper describe on the spectrum analysis of underwater noise by engine generating in small fishing boat in order to build up comfortable environment for fisheries man and to reduce ambient noise. The obtained results are summerized as follows:1. When the underwater noise of 10ton class fishing boat measure and the frequency spectrum in varied revolution of engine 750, 900, 1000rpm analyze, the frequency pattern is similar to each other, the faster revolution of engine increase, the higher frequency spectrum level becomes. 2. In comparison of spectrum level of underwater noise between 10ton class and 14ton class fishing boat, the former level is higher than the latter. 3. Frequency spectrum pattern of two 14ton class fishing boat is similar to each other but spectrum level is a little difference, it is suggested to different by fitting condition of engine.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.3
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• pp.351-360
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• 2011

In order to reduce the casualties of fishing boats, the author analyzed the fishing boat accident on the 412 cases in Korean maritime safety tribunal for the 2005~2009, and then studied the relation between the weather element and the accidents. According to this studies, the occurring ratio of sea casualty for fishing boat in fog weather was appeared 1 boat per 1.6 days. It means that the restricted visibility condition gives the most influence on the fishing boat accident. The casualties in winter season from November to next January occurred 139(33.7%), and small boats less than 50tons broke out more casualties with 68.4%. From this we can find that small fishing boats are very deeply affected on the sea weather condition. According to the boat types for fishing the casualty of jig boat was ranked first, and collision accident account for first with 77.9% for the types of casualties. As mentioned above, most sea casualties for small fishing boats were resulted from the human factors such as poor watch keeping in invisibility and the bad sea condition, it is necessary for navigation operators and the manager to take more attention to the meteorological factors.

• Bulletin of the Society of Naval Architects of Korea
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• v.21 no.3
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• pp.1-10
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• 1984

The computer programs of effective horsepower estimation of small fishing boat were developed, which was based on the statistical analysis of model test results. From the EHP estimation by these program and experimental model tests of practical fishing boats, the estimation accuracy was verified with maximum deviation of about 10 percent. Also, the EHP estimation accuracy was practically applied to initial design of four small fishing boats, and after the tank tests, the EHP reduction of the order of 15 to 25 percent was confirmed, as compared with existing ships. Moreover, a computer aided design procedure of fishing boat's hull form has been proposed in this study. The practical use of this procedure of fishing boat's hull form has been proposed in this study. The practical use of this procedure was demonstrated with the hull form design results of several fishing boats.

• The Journal of Fisheries Business Administration
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• v.29 no.2
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• pp.163-175
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• 1998

The decrease of the fishery's business performance is due to the changes of environment-the increase of cost, the reduction of resources, the liberalization of import, the effectuation of the admiralty law Though the government has prepared the alternative policy to strengthen the competitive power of the fishery, fishermen should draw up a plan to improve the business performance. The problems of the small powered purse seine resulting from the small scale of the fishing boat is following. First, its catching activity in the sea is riskful. Second, the space to eat and to work is not enough. Third, the space to put the fish is not enough, it is hard to maintain the freshness of the fish. Therefore it is necessary to solve these problems for the scale of the fishing boat to have to be enlarged. The enlargement of the fishing boat to be required much expenditure of fund is the important investment decision to fishermen. The alternatives evaluation between the existing boat(defender) and the new boat enlarged with the new equipment(challenger) is necessary process to reduce the uncertainty of investment. The profitability of the challenger is better than that of defender due to the reduction of cost and the increase of revenue. Because the net present value of incremental cash flow is positive, it is rational for fishermen to accept the challenger.

• Journal of Ocean Engineering and Technology
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• v.23 no.6
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• pp.71-76
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• 2009

This paper describes a statistical analysis method for predicting a coast fishing boat's effective horsepower. The EHP estimation method for small coast fishing boats was developed, based on a statistical regression analysis of model test results in a circulating water channel. The statistical regression formula of a fishing boat's effective horsepower is determined from the regression analysis of the resistance test results for 15 actual coast fishing boats. This method was applied to the effective horsepower prediction of a G/T 4 ton class coast fishing boat. From the estimation of the effective horsepower using this regression formula and the experimental model test of the G/T 4 ton class coast fishing boat, the estimation accuracy was verified under 10 percent of the design speed. However, the effective horsepower prediction method for coast fishing boats using the regression formula will be used at the initial design and hull-form development stage.

• Journal of Korea Ship Safrty Technology Authority
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• s.22
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• pp.34-53
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• 2007

In the case of hull material. large sized merchant ships are made of steel, on the other hand FRP or wood are used for small sized fishing boats. At present in Korea approximately 88,500 fishing boats are in operation of which 70% are made of FRP In the meantime, stainless steel is frequently used as shaft materials of the small-size FRP fishing boat. Namely, the kinds of shaft materials are STS 304(18Cr-8Ni), STS 316(18Cr-12Ni-2.5Mo steel) and STS 630(17Cr-Ni-Nb steel)etc. Among these things, STS 304 which is the cheapest and having ordinary corrosion resistance is most widely used as 2nd class shaft material. But, using STS 304 for shaft system material of the small-size FRP fishing boat on seawater environments entails a severe corrosion which causes shaft system troubles. Particularly, the corrosions tend to be concentrated of the stern and bow side, propeller shaft surface of inside of stern tube and the boat having no stern cooling pipe line system. As a solution for those problems, research on the ways to mitigate corrosion on the part of 2nd class stainless steel shaft have been undertaken. In the result, not only clarification for the reason of corrosion of the part of stainless steel shaft used mainly for the small-size FRP fishing boat was done, but also most optimal corrosion protection system was developed by experimenting shaft's protection simulation based of the electrochemical cathodic protection principle. In addition, verification through the field test on the optimal cathodic corrosion protection method by means of aluminum sacrificial anode was carried out. In this study, effective and economical shaft's protection system is suggested to the small-size FRP fishing boat operator by substantiating the results obtained from the research on the optimal cathodic protection.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.574-579
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• 2016

Grid systems used in previous studies were determined to be valid only if the length between the perpendiculars in a model ship was in the range of 6-8 m, and the maximum dynamic trim angle was smaller than $1^{\circ}$. The application of the grid system to a small fishing boat can create numerical instability because the dynamic trim of small boats is generally larger than $3^{\circ}$, and their Froude numbers are in the range of 0.3-0.8. In the present study, resistances of a small fishing boat were stably obtained by reducing the length between the center of buoyancy and the inlet boundary of the numerical domain, and by refining grid cells vertically in a region that would be swept by a free surface. The effective power of the small fishing boat was predicted based on the ITTC-1978 two-dimensional analysis. By using the results of previous towing tank tests, the coefficient of quasi-propulsive efficiency and the brake horsepower at a design draft were calculated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.1
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• pp.30-35
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• 1988

An electrical power generation system driven by main engine shaft, briefly SG system for middle or small size fishing boat is studied experimently. In the SG system, power transmission is performed by a variable displacement hydraulic pump driven by the main engine and a constant displacement hydraulic motor. It was verified that the SG system enabled the generation of electrical power with constant frequency regardless main engine speed. In the SG system, setting reference frequency, sensing generator output frequency and setting controller parameters are performed by performed by programming in a microcomputer, so a countermeasure for physical situations of control object is very easy. Futhermore, the SG system has following features; low initial installation cost, wide freedom of installation in engine room, advantage of application in existing ships, especially fishing boat with hydraulic fishing equipments.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.6
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• pp.757-762
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• 2010

Korean fishing boats have had appropriate hull forms for the safety, stability and convenience of fishing ability. However, Korean fishermen are recently concerned about the resistance performance and speed of Korean fishing boats, because the prices of fuel oil are gradually risen, also the exhausting of fish resources and the demand of high speed fishing boats are increased. Therefore, the necessity of the study on the improvement of resistance performance for Korean small coastal fishing boats is gradually increased. This study compares the hull form characteristics of Korean fishing boats with those of Japanese fishing boats, and the hull form of a representative Korean fishing boat is modified. From the modification of the hull form parameters for the Korean fishing boat, the improvement of resistance performances is evaluated. Moreover, the increase of resistance performances is also achieved from the modification of local characteristics for the hull form of the Korean fishing boat. A computational method and ship model tests in towing tank are used for the conformations of the improvement of resistance performance.