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Article type: Cover
1990 Volume 83 Pages
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Published: September 20, 1990
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Article type: Cover
1990 Volume 83 Pages
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Published: September 20, 1990
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Yoshinori MIYAMOTO, Etsuyuki HAMADA, Yasuyuki SHIRAI, Kiyotaka SAITO
Article type: Article
1990 Volume 83 Pages
1-5
Published: September 20, 1990
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This study was conducted to calculate all the Poisson's deviation coefficients, and to obtain the effect of changing magnetic latitude by computer simulation. These coefficients consist of the induced magnetism coefficients and the permanent magnetism one. In our electronic compass, these coefficients were calculated by measuring the vessel's magnetic force in the rectangular coordinates on four magnetic headings (N, E, S, W) under the vessel in level condition, and on another heading in any pitching or rolling condition. After that, the electronic compass can always indicate the true magnetic heading at any magnetic latitude and any vessel's attitude that was confirmed by the computer simulation. A model vessel was used in the simulation in which the vessel was navigated from Tokyo to Fremantle by way of Singapore. The result was given a good performance compared with the ordinary magnetic compass.
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Hyeon Ok SHIN, Etsuyuki HAMADA, Hiroshi SUZUKI, Yoshio KOIKE
Article type: Article
1990 Volume 83 Pages
7-11
Published: September 20, 1990
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Remotely operated vehicle (ROV) is a useful tool in underwater investigation. However, the guidance of ROV to a target is a very difficult task without the assistance of a locating system. We, therefore, tried to develop a locating system for the ROV which displays, in real time, both the locations of a ROV and a target by the use of multiple pingers (ultrasonic fish tag) of a single frequency attached to them. From a practical point of view, the authors adopted a form of time division scheme in order to distinguish each pinger. The system consists of four hydrophones, a four channel-receiver, and a personal computer. As the signal is received, it interrupts onto a personal computer so that the signal can be processed. When three pulses of an interval are found in the received pulse train, a corresponding pinger can be identified. Tracking of the pinger can be performed by the prediction of the next receiving time of the pulse using both the phase difference and the pulse interval. The same is to be applied to other pingers. In this system, the pinger position is calculated by the method of hyperbolic line of position calculation. In the experiments, the guidance of ROV to the target pinger was achieved with ease, and each pinger was distinguished successfully.
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Ryuichi KIMURA, Saburou SUZUKI, Yoshirou IMAEDA
Article type: Article
1990 Volume 83 Pages
13-19
Published: September 20, 1990
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Horn-signal is very important information. If the direction of signal-source can be detected by the horn-signal generated from other ship, it would be very useful for the safety navigation. This paper describes the system detecting the signal direction automatically. In this system, we consider a series of process of the sound sampling, data processing, direction detecting, as a sequential operation and examine algorithm which can quickly perform these processing by a personal computer. As a result, the detection takes time of 7 seconds each.
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Tomihiro HARAGUCHI
Article type: Article
1990 Volume 83 Pages
21-28
Published: September 20, 1990
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In model experiments on a vessel towed by a carriage, the optical motion measurement system using two video trackers and cameras is the most preferable because the optical system need only target lamps on a model, even if she is far away from a towing carriage. In this paper, the components and principle of the optical system are described as well as measuring accuracy. Furthermore, the optical system was applied to a model experiment, in which models of a barge type and a semisubmersible type were towed by a carriage in regular waves. The motions of a model were measured by the optical system and also by gyroscopes and accelerometers on the model. The measurement results by the optical system are compared with those by the other equipments and the effectiveness of the optical system is shown.
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Susumu KUWASHIMA, Akio YASUDA, Yoshiaki KUNIEDA
Article type: Article
1990 Volume 83 Pages
29-35
Published: September 20, 1990
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Measurement of wave direction using a Doppler radar was tried in model basin and in real sea field. It is a principle in this measurement that the direction of the fastest wave velocity which come close to a fixed position is the main wave direction, and the velocity rate is relative to the gap from main direction. The basic characteristics of detected wave velocity by the radar is cleared in a model basin. And some example measurement of wave direction on ship were carried out in the real sea field. In the results, although there are still many problems, the possibility of wave direction measurement is enough to be established.
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Hirotsugu WAKE, Kanemichi KASAHARA, Nobumichi ISHIMURA, Yuji HAYASHI, ...
Article type: Article
1990 Volume 83 Pages
37-47
Published: September 20, 1990
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A new system for automatic correction of nautical charts is proposed. This system consists mainly of a X-Y plotter and a microcomputer for its control as hardware, and as software, a database to offer information for correcting charts and a system software. In the database, the information described in "Notices to Mariners" published Japan Maritime Safety Agency is arranged in the very compact form of symbols by using the hierarchy structure introduced in the classification of contents about chart correction. This compactness allows this system to become small size and, as the result, to operate usefully on board. The performance of this system is discussed in comparison with the chart correction by hand and the adaptation to actual corrections is investigated. It shows that the percentage of automation reaches 96% in all paragraphs of "Notices to Mariners".
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Naoto SATOH, Yasumitsu MIYAZAKI, Yasuo TAKENAKA, Takaaki NISHI, Kazuo ...
Article type: Article
1990 Volume 83 Pages
49-56
Published: September 20, 1990
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In the summer of 1989, a series of measurement of the 9970 Loran-C chain and the Kita-Kyushu Decca chain was made, using two ρ-ρ Loran-C receivers and a MS-2A Decca receiver aboard the training ship Hiroshima-maru. We made a series of passage under the Bisan-Seto-Oohashi which is located in the Inland Sea of Seto, observing the time-difference, amplitude and phase-difference on the receivers. When the ship was located in the vicinity of the bridge, large positioning errors were observed as the result of the field distortion. This paper presents the results of these measurement, and says that the disturbance of the electric field can be explained by assuming the bridge to be a one-wave-long-loop antenna.
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Naoto SATOH, Yasumitsu MIYAZAKI, Yasuo TAKENAKA, Keisuke TSUJI
Article type: Article
1990 Volume 83 Pages
57-64
Published: September 20, 1990
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The authors made an attempt to estimate the overall length of a vessel indicated as a target on a radar PPI. It was assumed that an estimate of the overall length was given by the formula of a linear multiple regression model. To find estimates of parameters appearing in a functional dependence between variables, we applied the method of least squares. The variables of the function were experimentally determined from the measures of an image on a radar PPI by using the image processing techniques. In this report we are going to report on the results of measurement from the marine traffic survey in Akashi channel obtained by using the aforementioned method. The conclusions are as follows. As for the results of comparison between the data estimated from the linear multiple regression equation and those from the actual ship, the agreement is remarkably good. The improvement of the image processing techniques shows the possibility of the automatic analysis of the marine traffic.
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Jiro MOCHIZUKI, Takahiro TSUJI, Susumu HASHIMOTO
Article type: Article
1990 Volume 83 Pages
65-70
Published: September 20, 1990
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This paper shows the results of an experimental study on the extent of the visible horizon, on the hue of fixed stars and planets in the duration of twilight in the South Pacific Ocean (36°-16. 2'S, 178°-09. 2'E). We thought the sight of the horizon depends upon the contrast between the luminance of the sky (L_1) and the luminance of the sea (L_2). That relation showing brightness contrast (C) is, C=(L_1-L_2)/L_1 (0≦C≦1) The results of this experiment are shown as follows; (1) The brightness of the sea surface depends upon the brightness of the sky. (2) The luminance of the sea surface which can be recognized in sight of the long telescope of a sextant is 0.05〜0.04cd/m^2 and then the altitude of the center of the sun is roughly-9 degrees. (3) Planets begin to become visible and unvisible just at sunset and sunrise. (4) The first magnitude fixed stars can be recognized in the sky when the altitude of the center of the sun is roughly-6 degrees. (5) The duration of nautical twilight is the period between civil sunset/sunrise and the altitude of the center of the sun, which is-9 degrees (the 1/2 of the duration of astronomical twilight).
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Kiyoshi HARA, Akira NAGASAWA, Shinya NAKAMURA
Article type: Article
1990 Volume 83 Pages
71-80
Published: September 20, 1990
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A way to assess subjectively the risk of collisions between ships was developed to design new traffic routes and evaluate the change of marine traffic environment. Authors analyzed factors concerned with the risk assessment on ships collisions, using radar simulator and ship handling simulator. The results of pre-experiment indicated that two parameters, distance between ships and changing rate of relative bearing to target ship were useful to assess risk of ships collisions, rather than other parameters such as TCPA and DCPA. Regressive formulas to assess risk categories (danger area, caution area, safety area) were drived from total about 30,000 data points of simulator experiment. This experiment was carried out on pilots, captain and officers, by using mainly radar simulator with asking subjective categories to assess the risk collisions on traffic situations at every one minute. As a practical application, the assessment of risk categories, in case of crossing Akashi Strait, was carried out using above the regressive formulas, and we got reasonable results.
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Takahiro TAKEMOTO, Hisashi KUGUMIYA
Article type: Article
1990 Volume 83 Pages
81-89
Published: September 20, 1990
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Many accidents generally end up happenings caused by some factors in connection with other factors, and ship-bridge collision accidents are no exception. To prevent the likelihood of recurrence of ship-bridge collision accidents, it is necessary to investigate what factors contributed accidents and how one factor connected with others. In this study we tried to clear up the processes of ship-bridge collision accidents and to extract important factors related to them by means of Fault Tree Analysis. Fault Tree Analysis is known as a primary method for large-scale-system to evaluate the safety at design stage, but also it would be used for accident analysis; if every factors related to accidents were expressed by figures and accident processes were cleared up, it could be possible to make an effective choice to prevent the accident. By constructing Fault Tree, we could clear up the processes of ship-bridge collision accidents, and could extract some important factors by determining the minimal cut set and the minimal path set for the simplified Fault Tree.
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Masaaki INAISHI, Hisashi MATSUMURA, Saburo TSURUTA, Hayama IMAZU, Akio ...
Article type: Article
1990 Volume 83 Pages
91-98
Published: September 20, 1990
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Evaluation, whether informal or formal, is an important step in ship expert system development. Evaluation enables a feedback process to take place whereby the comments are served as a basis for iterative refinements of ship expert systems. However, it is still a problem even today that the establishment of ship expert systems evaluation method. In this paper, authors have classified evaluation process, and have proposed evaluation method of ship expert systems. This evaluation method contains evaluation purposes, evaluation items, evaluation criteria and synthetic evaluation technique. Using this evaluation method, three prototype expert systems for navigation at sea which have been developed by authors are evaluated. The summary of the results is shown below. (1) The availability of evaluation items hierarchical classification is given. (2) Evaluation items and evaluation criteria which are necessary to evaluation of ship expert systems are proposed. (3) Evaluation results which coincide with purposes of system development are obtained. (4) The validity of evaluation method is supported by evaluation results investigation.
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Hidefumi HARASAWA, Masaaki INAISHI, Akio M. SUGISAKI
Article type: Article
1990 Volume 83 Pages
99-105
Published: September 20, 1990
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Recently foreign trade goods are a tendency to increase in volume and have a various character. It is an important problem that customs brokers work economical and efficient for a customs procedure. The purpose of this study is to build intelligent support system for classification of trade goods operation and to resolve the problem. The authors acquire a knowledge from the registered customs specialisc and some literature for classification of trade goods operation. The acquired knowledge is represented a goods thesaurus dictionary which is used to change some goods names into one controlled goods name and frame rules which is used to apply classification rules and to deside a statistical number. This system was composed of four sections, which is a controlled goods names reference section, a statistical number decision section, an operational memory section and a user-interface section. This system is written C-language on a personal computer. The summary of results is shown below. (1) A plan for systematic customs procedure is suggested to classify the classification of trade goods operation. (2) A performance of this system is found to support a registered customs specialist's operation and a customs officer's operation. (3) An action of this system agrees with classification of trade goods operation by the registered customs specialist.
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Yuji MATSUDA, Masaaki INAISHI, Akio SUGISAKI
Article type: Article
1990 Volume 83 Pages
107-112
Published: September 20, 1990
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The import and export trade of our country has been developed so remarkably. The tremendous amount and the immense variety of the freight to be dealt with have necessarity brought about the increment of complicated trading operations and jobs. To cope with the difficult situation, the systematization in every field of international trade has been projected and realized ardently, though it is far from being completed for the present. This system consists of 4 functions: Knowledge Base, Inference Engine, User Interface and Working Area. Knowledge Base is the data on files which is represented by retrieved knowledges. Insurance Engine is a set of functions written in C language. Interface gives facilities for input-output between the system and user, and Working Area is used for maintaining the data. A study examines the possibility of introducing 'expert system' into the estimation of trade cost. The summary results of the study are shown below. (1) The steps of trade cost computation are analysed functionally and thereby the functions relevant to the systematization are revealed. (2) The pieces of the knowledge acquired with regard to the jobs are classified and reorganized according to their conceptually hierarchical order. (3) 'Frame' proves efficient for the representation of the acquired knowledge. (4) The Infelence engine can be constructed which is most adapted for the representation of the knowledge. (5) The Inference engine is detached completely from the knowledge base.
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Toshihiko MATSUO
Article type: Article
1990 Volume 83 Pages
113-120
Published: September 20, 1990
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In Japan, the role of domestic shipping has been important on the physical distribution. But, its role is changing through the industrial restructuring. Now is the time to reconsider this role of domestic shipping. This report shows the analysis of a shipper's mode choice on the physical distribution by the multivariate analysis (principle component analysis, cluster analysis and discriminant analysis). The obtained results are summarized as follows; (1) There is a local feature in the role of domestic shipping. (2) Discriminant analysis model by distance and lot as predictor variables is effective for mode choice.
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Takashi YOSHIZAKI, Taketoshi YAMADA
Article type: Article
1990 Volume 83 Pages
121-130
Published: September 20, 1990
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The authors describe the results of the logistics systems analysis of integrating production, inventory of overseas distribution center and multi-echelon international container transport, making use of computer simulation models. The fixed ordering point inventory system with economic order quantity (EOQ) is adopted and the overseas distribution center is usually replenished by the surface transport mode with lead time variation. And in addition, mixed mode transport and dual reorder point system in which the center is complementally replenished by the fast air mode in addition to the usual surface replenishment is adopted in this model. And making use of the simulation outputs, logistics cost analysis which focuses on the tradeoff among inventory cost, transport cost and stockout cost is carried out. The results of the analysis are as follows. (1) The variation of service level to the probability of stockout is about ten percent caused by the lead time element variation of each echelon of surface transport and the time lag among reorder time, shipment time at production and ship arrival time. (2) The service level of the distribution center increases when second reorder point for the fast air mode replenishment takes the value about forty percent of EOQ. (3) In the case of seasonal demand variation, the dual reorder by the fast air mode replenishment becomes more effective when the rate of present sales profit loss in the large stockout quantity exceeds fifty percent. (4) The estimation of loss caused by stockout is very difficult. But the dual reorder and fast mode replenishment become more effective when utility loss of waiting customers in backorder system is estimated so large and future profit loss caused by the loss of goodwill is added.
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Susumu OHTA, Tamaki URA, Takashi SAKAMAKI
Article type: Article
1990 Volume 83 Pages
131-137
Published: September 20, 1990
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Tilting box tests and triaxial compression tests for a grained material were carried out to investigate the adequacy of existing IMO recommendation on the trimming for solid bulk cargoes. The numerical analysis which is generally utilized for assessing slope stability in soil mechanics is introduced to evaluate the sliding failure on the basis of these data. It is shown that cohesive materials may slide even if the summation of heeling angle and slope angle is less than the angle of repose which is measured by tilting box tests. The safe slope angle chart is proposed as a new trimming guidelines for cohesive materials. It can be derived from safety factors for sliding failure calculated by rigid-plastic analysis.
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Seiichi TAKEDA, Kaname SATOH, Kiyoshi INOUE
Article type: Article
1990 Volume 83 Pages
139-148
Published: September 20, 1990
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It is important to confirm the hull response of a fishing boat in operation for checking the safety sea-keeping qualities and automation of fishing. For this purpose, a hull response system was developed and installed on the training ship Shinyo-maru (Tokyo University of Fisheries). Before a long time testing on board, we had a performance test for the system when the ship was on the still water. We measured and analyzed specially on the longitudinal bending stress. It was confirmed that the experimental values acting on the midship agree with the calculated one. Also the hull response while cruising was analyzed utilizing on board test of the system. Using wave direction as a parameter, a high correlation between the wave height and the hull responses, as well as among each of hull responses was obtained. This suggests that one of the hull responses could be estimated using the value of other hull response.
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Akira FUKUCHI, Akihiko HORI
Article type: Article
1990 Volume 83 Pages
149-154
Published: September 20, 1990
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We studied optimal routing to the destination when inshore ships will encounter rough sea. The route is to get minimum-time paths through a region of position-dependent vector velocity by optimization for dynamics systems. The ship speed reduction by wave height and direction in addition to ocean current was taken in this paper. The data area is 400 miles from east to west and 300 miles from north to south. The lattice points are divided into every 50 miles and 30 miles along X and Y-axis. These data are based on wave prognosis chart and sea surface current chart near Japan by weather facsimile. We are comparing the optimal routing with the direct routing to prove the validity of this method.
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Hideki HAGIWARA
Article type: Article
1990 Volume 83 Pages
155-167
Published: September 20, 1990
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This paper gives the innovative methods to perform stochastic weather routing. Based on the information of the accuracy of predicted winds, waves and ocean currents, a method of estimating the standard deviations of passage time and fuel consumption on a particular route is described. By incorporating these standard deviations into the objective function, a method to perform stochastic minimum time/fuel routing is proposed. After showing the wind, wave and ocean current data of the North Pacific Ocean as well as the mathematical model ship, various kinds of stochastic routing simulations are carried out for Tokyo-San Francisco route. As a result of the simulations, it is concluded that the proposed method can provide the shipmaster/owner with sufficient information to determine the optimum route in the stochastic sense.
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Keinosuke HONDA, Hiroyuki SADAKANE
Article type: Article
1990 Volume 83 Pages
169-176
Published: September 20, 1990
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A ship-generated waves, i.e., ship-waves, may very possibly be caused the capsizing or beamends to a small boat with poor stability. In this paper authors deal with some problems on the strong rolling of a boat in ship-waves from a viewpoint of manoeuvring. Main experimental results from model tests and actual ship tests are as follows, (1) The effect of ship-waves on the strong rolling of a boat is more of the divergent wave than the transevere wave, and the clear relations are observed between the magnitude of these wave height and the speed, boat-clearance, block coefficient of a sailing vessel. (2) The strongest rolling of a boat in the ship-waves causes in case that a boat is set on the direction line of cross angles 30°〜45° to the sailing line of a vessel. This result agrees approximately with the result of actual ship test. (3) When the head of a small ship with very lower freeboard and poor stability is set on the direction line of cross angles 60°〜90° to the sailing line of a vessel, the small ship get into quite frequently the beam-ends.
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Michitoshi ISOZAKI
Article type: Article
1990 Volume 83 Pages
177-184
Published: September 20, 1990
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Nippon Maru, 2570 tons, 4-masted bark, was built in 1984 as a sail training ship. Experiments to measure her sailing performance by several researchers have been carried out, and her characteristics is gradually being clarified. The author measured the Leeway on her various conditions. The summary of the results are as follows. (1) The Leeway mostly depends on ship's speed, angle of yards and apparent wind direction. (2) The Leeway also depends on sail condition. (3) The Leeway is able to estimate using some factors. (4) An ideal sailing method from the Leeway point of view is shown.
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Kunisaburo YONETA, Syunji JANUMA, Keiichi KARASUNO
Article type: Article
1990 Volume 83 Pages
185-192
Published: September 20, 1990
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The authors proposed physical-mathematical model consisting of six elemental forces of fluid-dynamics and stall phenomena. These forces influence ship motion, and in this study the entire range of wind direction was modeled. The equations below describe forces: [numerical formula][numerical formula][numerical formula] u'=cosβ=u/U v'=-sinβ=v/U Analysis results of data previously presented in papers about wind forces acting on various ships are summarized below. 1) The authors proposed mathematical model can be applied to many ship types, and it well describes the respective wind forces of ships. 2) The pattern of lateral force vs. wind direction (Y'-β) should be estimated from the ratio of the area between the superstructure and the vessel's hull. 3) Yaw moment, due to cross flow drag N'_<vvv>v'^3, should be estimated from the superstructure's longitudinal location on the hull. 4) There are correlations between coefficients of wind forces (Y'_<uuv>, Y'_<vvv>, m'_x-m'_y+N'^*_uuv) and aspect ratios of the ships (k). 5) A few longitudinal force coefficients of stall effect should be estimated from coefficients of Y'_<uuv> and Y'_<uuvvv> determined by using lateral forces Y'.
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Rihei KAWASHIMA
Article type: Article
1990 Volume 83 Pages
193-201
Published: September 20, 1990
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By analysing the nonlinear differential equation for ship rolling motion, the geometrical figure of Poincare mapping obtained shows a polygon and it's number of side has the relation to the ratio between the period of input force and Strobe period. Then, the geometrical figures of Poincare mapping are given for the period of input force calculated from the ratio as the parameter, systematically. Using Poincare mapping obtained from the experimental data in wind waves and parameters deduced from input force period in power spectrum of pitching motion, the similarity of rolling motions for the mathematical model and experimental ship model has been discussed on the geometrical figure of each Poincare mapping.
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Kawilarang W.A. MASENGI, Keishi SHIBATA
Article type: Article
1990 Volume 83 Pages
203-211
Published: September 20, 1990
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K.W. Alex MASENGI, Hisaaki TAKAYAMA, Hideaki NISHIDA, Shigeru HAYASHIT ...
Article type: Article
1990 Volume 83 Pages
213-220
Published: September 20, 1990
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The traditional small fishing boat of Sabani in Okinawa is well known to have a less resistance and good surf-ridings. Till the beginning of Showa era some fishermen took an offing to fish sharks by sailing on a slim shaped Sabani. A series of resistance tests was made on this Sabani and compared with other small fishing crafts, i.e., two Wasens of Japan and two Canoes of Indonesia. From the results of tank tests, we found that the Sabani has very less total resistance coefficient of under 0.04 in 5γt (five-ton displacement) between 0.2 and 0.9 of Fn∇ (speed and volume of displacement ratio=v/√<∇^<1/3>・g>) and between 0.09 and 0.38 of Fn (Froude's number=vm/√<l_<w1>・g>). The peak values of 5γt at the last hump is near 0.09 at 1.3 of Fn∇ (same as 0. 53 of Fn). Therefore the resistance coefficient of Sabani stands in between Wasens and Canoes. To explain the resistance coefficient curves and their relationships, we consider that the prismatic-curves of each craft are very important and helpful.
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Kinzo INOUE, Motoaki HANAHUSA, Yoshiyuki KOTOKU
Article type: Article
1990 Volume 83 Pages
221-229
Published: September 20, 1990
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During the past two decades, the accident due to dragging anchor has caused concern mostly to Pure Car Carriers (PCCs) because of her huge superstructure. Drastic measure is required if such danger is to be avoided. In order to reduce the danger of dragging anchor, the growth of the transverse and rotational velocity during the yawing motion of the vessel should be controlled. The fluid resistance acting on the board attached perpendicularly to the bottom of the vessel along her keel line can be expected to control her yawing motion and thus reduce the force acting on her anchor. The effectiveness and the possibility of actualization of this "under keel vertical fin" was examined through model test and simulation. Under the condition that the 16,000 GT type PCC is moored at anchor with 7 shackles of cable under the wind velocity of 20 m/s, when the rectangular board with 1.9m depth is attached afore the midship, the force acting on the anchor can be reduced by 70%. In case of 3.0m depth, the force reduction is by 60% and in case of 4.8m depth, it reaches to 50%. It can be considered that the under keel vertical fin has the ability to achieve the safer anchoring under the heavy weather.
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Kuniji KOSE, Tatsugoro NAKATANI, Takashi NOBUKAWA, Yuzo NAKAMURA
Article type: Article
1990 Volume 83 Pages
231-240
Published: September 20, 1990
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The Japanese Pilots' Association has listed out a significant number of ships with extremely poor maneuverability. The ships are under operation in ports and waterways near Japan and dangerous experiences happened on such ships have been pointed out by the association. These show us an urgent necessity of the maneuverability standards which are the minimum requirements in maneuverability of ships. To evaluate relations between the maneuverability and the operational safety from the viewpoints of marine pilots, simulation studies were carried out as a cooperated program between the Japanese Pilots' Association and Hiroshima university. Maneuvering simulations of berthing in some port and passing though a curved narrow channel were conducted by pilots on the Harbor Maneuvering Simulator of Hiroshima University. The difficulty was assessed by the pilots. The results of performed maneuvers were carefully examined and the relation between both results was also confirmed. The allowable instability limit estimated from the present simulator studies is finally reported.
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Hiroaki KOBAYASHI, Akira OGASAWARA, Atsushi ISHIBASHI, Hisayuki KUROKA ...
Article type: Article
1990 Volume 83 Pages
241-247
Published: September 20, 1990
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The ship's maneuverability is one of the important factors of the safety handling in the congested waters, however, the relation between the maneuverability and the safety is not still cleared. When the Collision avoiding is considered, the parallel course shift maneuver is typical handling pattern. There are three important factors in this maneuver. 1st one is "When it must be started", 2nd one is "How to steer", last one is "How many distance must be kept away from the target." The required advance to do this maneuver was studied in relation with the maneuvering characteristics of ships. A large ship needs longer advance than a small ship to avoid the collision. Minimum time control was employed as a base index of this distance. The obtained value by this method is the minimum, so that a human operator can not follow this control law. Simulator studies were made to know the relation between the minimum advance and practically necessary advance by human operator. According to this study, the practical advance seems to be 2 times longer than minimum advance. Owing to the observation of Marine traffic, almost vessels keep the 1.6 times of own ship's length (L) away from the target. Considering all these factors, we get the necessary area which is needed for safety maneuver. The area is defined by 1.6*L width and necessary advance being decided by its maneuverability. The safety of the specific area is decided by the ratio of the area which all ship occupied in this area to the water area. This method is verified by comparing the annual collision rate with the area ratio which is obtained by this method. (shown in Fig.8)
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Muneyuki OKUMURA
Article type: Article
1990 Volume 83 Pages
249-255
Published: September 20, 1990
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In this paper, the author reports the manners of watch-keeping aboard small domestic vessels after having talks with the masters of those vessels. The motive of this investigation was that while reading the Judgments by the Marine Accidents Inquiry Agencies, the author has had some doubts if the midnight watches were left to unlicensed persons on most of such vessels. The results are that the turns and hours of the watches on those vessels are very miscellaneous and that above doubts are unnecessary. Besides, other matters relative to watch-keeping are treated.
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Shogo HAYASHI, Susumu KUWASHIMA, Koukichi SOTOOKA, Hisao YAMAZAKI, Hir ...
Article type: Article
1990 Volume 83 Pages
257-266
Published: September 20, 1990
Released on J-STAGE: January 15, 2017
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The experimented stranding avoidance system was developed to achieve a full-automated equipment without any helps of ship's crew. Digital charts and radar image were used for obtaining the high precise ship's position in this system. Detection in the water using sonic or ultra sonic is difficult problem, because the path of the sound must be estimated precisely for over 1000 meters ahead. The method using high precise position that is obtained from digital image matching of digital charts and radar image is used to judge the danger of stranding from full up-dated digital charts, and a sound alarm or warning signals are generated with this system for the crew. The several experiments were made using a training ship (425 G/T), and the evidence of effectiveness was obtained about the performance of stranding avoidance.
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Tadao TAKAI, Kohei OHTSU
Article type: Article
1990 Volume 83 Pages
267-276
Published: September 20, 1990
Released on J-STAGE: January 15, 2017
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In order to operate the berthing maneuver automatically, a control system was developed. This system is composed of a ranging system and a controller. A control logic based on a prediction of a motion was adopted and a feed back control was used subsidiarily to improve the performance of the system. Actual trial using this automatic berthing system was executed. And following results were obtained. (1) The smooth course was obtained during the trial. (2) The final position error and the berthing velocity seem to be acceptable. (3) A control logic based on a prediction of the motion did not operate successfully but a feed back control recovered this well.
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Yukito IIJIMA, Hideki HAGIWARA, Hironao KASAI
Article type: Article
1990 Volume 83 Pages
277-287
Published: September 20, 1990
Released on J-STAGE: January 15, 2017
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A collision avoidance system has been developed using a knowledge-based (expert) system originally built for experimental study on integrated autonomous ship control for piloting, navigation and on-board management under substantially no assistance by the crew. For confirmation of its effectiveness, full-scale performance trial was carried out using an experimental prototype of the above system and an ARPA as the target ship sensor on board a 425 GT-training ship 'Shioji-Maru' of The Tokyo University of Mercantile Marine, off the Bay of Tokyo near the Uraga Suido Traffic Route. Tests were run repeatedly over a period of a month and its autonomous collision avoiding performance was demonstrated successfully for real encounters, including fairly complex multiple meetings. On-board evaluations were made regarding the use of the system's graphic terminal display as a bridge collision-avoidance/navigation-aid, and its apparent adequacy has been verified. The system's potential multi-lateral use is pointed out as a navigation-aid and autonomous fail-safe system for existing ships, though an ARPA is still in some ways limited in automatic target acquisition reliability. From the viewpoint of an intelligent ship concept, future prospect of the above-mentioned system is discussed.
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Mitsuo YOSHIDA, Takashi KURODA, Hiroyuki SHIMADA
Article type: Article
1990 Volume 83 Pages
289-294
Published: September 20, 1990
Released on J-STAGE: January 15, 2017
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A social survey measuring images of the sea and ships was conducted between mercantile marine and general college students. Questionnaire items were concrete ones asking attitudes directly compared to our previous surveys designed by Semantic Differential method. Mercantile students had better images concerning the sea affairs. Likert method is a method to derive reasonable category weights that are defined as conditional means of Normal distribution. Almost all scores showed good agreement with the simple and popular weights. Statistical moments such as mean, variance, skewness and kurtosis of response distributions also indicated high consistency with those of Likert method.
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Article type: Appendix
1990 Volume 83 Pages
App1-
Published: September 20, 1990
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Article type: Appendix
1990 Volume 83 Pages
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Article type: Appendix
1990 Volume 83 Pages
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Published: September 20, 1990
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Article type: Appendix
1990 Volume 83 Pages
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Published: September 20, 1990
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Article type: Appendix
1990 Volume 83 Pages
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Published: September 20, 1990
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Article type: Cover
1990 Volume 83 Pages
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Published: September 20, 1990
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Article type: Cover
1990 Volume 83 Pages
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Published: September 20, 1990
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