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Article type: Cover
1985 Volume 73 Pages
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Published: September 20, 1985
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Article type: Cover
1985 Volume 73 Pages
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Published: September 20, 1985
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Tadashi NARITA
Article type: Article
1985 Volume 73 Pages
1-12
Published: September 20, 1985
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In this paper, two more applications of the FS (Free Surface) mechanization of inertial navigation are described. Each utilizes its own set of two spatial references, which is different from that of another. One of the applications, the type IN mechanization, uses as the references the north-south axis Y_n and the earth axis Z_E. The other, the Type I (2) mechanization, uses the axis Z_E and an inertial axis Y_I that is in the equatorial plane pointing to Z_E at the initial time t=0. In each case, the navigation equations are derived, referring to the respective references, from the fundamental equations of inertial navigation, and the solutions are effected by means of the block diagram method. Also how to find the geographic coordinates is described. This is necessary for obtaining the attitude angles (roll, pitch and azimuth). Moreover, to help understanding the general aspects of FS mechanization, several supplementary but substantial topics are disscussed. They are as follows; countermeasures to the non-uniformity of the specific force vector, ranges took by the angles a_i (i=1〜4) where a_i is the angle between the platform axis Z_p and the i-th reference axis, ranges of altitude time rates h and h which the altimeter must cope with, the relations between the outputs of the inertial navigator and the vehicle's motion, and so on.
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Masashi KATO, Yukio TARUMI
Article type: Article
1985 Volume 73 Pages
13-17
Published: September 20, 1985
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The purpose of this paper is to propose a method of the calculations for position fix. The authors examine whether it is possible to utilize a method of optimization for calculating ship's position, however utilizing a method of least-squares for calculating ship's position has been studied. In this method position circles or position hyperbolas are utilized for positionfix and optimum ship's position is gained by solving basic equations for position fix. The features of this method are as follows; (1) No straight lines are used in place of position lines. (2) No directions of geographical positions or radio stations are necessary. Expected results are gained as the method is applied to position fix in celestial navigation.
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Hayama IMAZU, Takeo KOYAMA
Article type: Article
1985 Volume 73 Pages
19-26
Published: September 20, 1985
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The subject of this study is to make an optimum criterion for collision avoidance action deciding by a navigator or collision avoidance aids. When the collision avoidance is done by own ship and targets, it is necessary to introduce a traffic rule in the decision-making model. Here, the decision-making model which considered about a statistical collision risk, action loss, and a traffic rule, was made. The results by the simulation tests showed that all targets could keep a safety distance between another targets, and these avoiding action were close to the action adopted by a real ship.
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Hideo YABUKI
Article type: Article
1985 Volume 73 Pages
27-34
Published: September 20, 1985
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From January to March in 1984, the phase data of Omega 10.2kHz signals are measured onboard, by a receiver with rubidium atomic standard, along the route between Japan and Western Australia for the purpose of analyzing the signal behavior and evaluating the relative error of LOPs by means of comparing with nominal LOPs (PPC included) by NNSS and Loran-C. Accordingly, recommended LOP combinations along the above route are selected in consideration of the relative accuracies of LOPs and Geometric Dilution of Precision (GDOP). As a result, signal behavior (10.2kHz) of A, G and H are confirmed to be almost the same as described in the Omega Coverage Diagrams. Accuracies of the Omega System are estimated 2〜3 N.M. (RMS) as a whole on the route concerned, but navigators should notice that it is difficult to make good Position Fix in the nighttime at the southern and the eastern parts of the South China Sea because of modal interference on H and G.
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Sakae NAGAOKA
Article type: Article
1985 Volume 73 Pages
35-42
Published: September 20, 1985
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This paper describes distributions of the relative velocity of a pair of aircraft in level flight based on empirical data obtained by the Navigation Accuracy Measurement System (HAMS) installed under a trunk airway. Distributions are related to parameters of a collision risk model for evaluating the safety of a parallel air route system. The results of analyses suggest that empirical distributions of relative velocities (relative along track velocity or relative cross track velocity) for pairs of aircraft in proximity in time domain can be approximated by the double exponential (DE) distribution rather than the Gaussian.
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Kunimitsu ISHIDA, Goro FUJISAKU
Article type: Article
1985 Volume 73 Pages
43-48
Published: September 20, 1985
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Acquirement of skills is an important part of training at the educational institutes of mercantile marine. Therefore it is necessary to think out an effective training method. In order to improve efficiency of the training, we have contrived two methods; REGULATION LIGHTS SIMULATION SYSTEM & RADAR PLOTTING INSTRUCTION SYSTEM with aid of CAI (Computer Assisted Instruction or Computer Aided Instruction). In REGULATION LIGHTS SIMULATION SYSTEM we adopted the method of individual learning. In RADAR PLOTTING INSTRUCTION SYSTEM we introduced color CRT display for plotting blackboard. We carried out a survey on the effects of training. By using these two methods we have got the better results of the practical training than the traditional methods.
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Takeshi FUWA, Kunihiko TANAKA
Article type: Article
1985 Volume 73 Pages
49-58
Published: September 20, 1985
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A fundamental study on the automatic navigation system is performed by means of computer simulation with a simplified model. There are three main functions in the system. The first is to determine the optimal ship's route. The next is the function to control and handle the ship along the route, and the last is to carry out a collision avoidance maneuver in case of necessity. In this paper ship's route is assumed to be given as a combination of straight lines, and algorisms and system design methods for the latter two functions are investigated. An auto-pilot designed as an optimal regulator for the ship and its situation shows satisfactory results in track keeping and course change. It is a feedback system of lateral deviation from the route, course angle error and rate of turn of the ship. Useful information for collision avoidance maneuver and collision avoidance system design is obtained through the simulation studies.
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Saburo YAMAMURA, Kiyoshi HARA
Article type: Article
1985 Volume 73 Pages
59-66
Published: September 20, 1985
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It is well recognized that a ship handling simulator is a very useful equipment for research and training of marine affairs. A projection system of the simulator in use of computer generated image (CGI) is said to be the most flexible and expensive of the various ones. Authors developed a ship handling simulator using CGI which was realized with the high cost performance by limiting simulated situations to nocturnal ones for the sake of reducing the overhead on the computer. A series of sailing experiments was carried out in a narrow fairway with the two kinds of arrangements of navigational bouys which were the same ones as CAORF. Experimental results of ship's tracks by the proposed simulator indicate the same trends as ones at CAORF. The validity of this simulator is also discussed.
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Kiyoshi HARA, Michiyasu ODANI, Hiroshi KURISAKI
Article type: Article
1985 Volume 73 Pages
67-73
Published: September 20, 1985
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Authors propose an assessment system of marine traffic environment based on ship's tracks in congested water observed by a shored based radar, which reflect turburances due to traffic and geographical enviroments there. Positions of a sailing ship are usually observed at a discrete time interval by radar, so they are interpolated by use of a spline curve. All ship's tracks are sorted in time in order to calculate relative motions between each ship. By the proposed assessment system both actual and simulated traffic situations are well recognized. Potential risk of encounter between ships are continuously derived based on exponential values of TCPA and DCPA which are normalized by observed length and speed of an objective ship. The assessment system is applied to the traffic situation in Kurushima Kaikyou, which is one of the most risky narrow channel in Japan. The results indicate the resonable correspondence to subjective assessments by navigators there.
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Takayuki MATUI, Yahei FUJII, Hiroyuki YAMANOUCHI
Article type: Article
1985 Volume 73 Pages
75-86
Published: September 20, 1985
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Study was made for further investigation of collisions and groundings in major channels and ports in Japan based on the current reports of marine traffic accidents in five years from 1978 to 1982. The probability of traffic accident, P, is calculated as the ratio of the number of accidents, N, to the number of geometrical accidents, Ng. The results of study give following values, LogP=-4.3±0.4 for collision of vessels in head-on encounter, LogP=-4.0±0.4 for collision of vessels in overtaking encounter and LogP=-3.8±0.3 for grounding. These values are similar to those obtained in former investigations in Europe and Japan. The risk of traffic accidents, R, is defined here as the ratio of the number of traffic accidents, N, to the traffic quantity, Q. The results show considerably large decrease in the collision risk in ports compared with those in the period from 1973 to 1975. The collision risks in major channels have also shown considerably large decrease, most of which lies in 1960's and little in 1970's. This might be the fruit of Marine Traffic Safety Law established in 1972.
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Toshiharu KAKIHARA, Saburo YANAGAWA
Article type: Article
1985 Volume 73 Pages
87-94
Published: September 20, 1985
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For the purpose of studying the effect of the masses of pole and line fishing boats and the fishing boats used for leisure at work upon the vessel traffic, the marine traffic survey was carried out by both visual and a radar in entrance sea area of the Tokyo Bay from first to second of July, 1983. The results can be summerized as follows: 1, The masses with high density of pole and line fishing boats and fishing boats used for leisure are formed upon the natural reefs off the Cape Tsurugi at daytime in summer. 2, When the masses of fishing boats at work are present in the vessel traffic flows, the flows separate and shift. And the index of encounter frequency (I_<en>) increases by 30 percent. 3, The clearance distance of the vessels underway from fishing boats at work is very small. About 33 percent of all clearance distance, converted one into ship length L, are less than 1.0 L.
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Tsuneo SUZUKI, Haruo SATO, Yuzo IGETA
Article type: Article
1985 Volume 73 Pages
95-101
Published: September 20, 1985
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The authors have continued the experiment on the sea to examine the drifting characteristics of several things drifting on sea surface, and knew that the exactitude of a seach area is largely controlled by the current in that sea area. However, since the correct estimation of this current is difficult, as the method of presuming a search area independent of current, the experiment using a SOS automatic transmission buoy (type FRB-52; SOS buoy) was attempted. The results are summarized as follows. (1) Similar to other drifting things, the SOS buoy is also driven by the current in that sea area leeward at the peculiar drifting velocity due to wind pressure. (2) Drifting human bodies showed the relative drifting velocity due to wind pressure in relation to the SOS buoy in the range approximately determined by the following equation according to the drifting posture. (See Fig.4) 0<V<0.017W+0.05 where, V: relative drifting velocity due to wind pressure (kn), W: mean wind velocity (m/s). (3) when the track of drift due to wind pressure in relation to the SOS buoy was determined from Fig.4 in the case of the wind blowing at the same velocity in the same direction, Fig.10 was obtained, and the position P of a drifting thing as seen from the SOS buoy at an arbitrary time is the point at the distance D determined by the following equation. D=2Rsinθ where, R: radius of relative track circle (N. M), θ°: half of the angle of change of wind direction wt° (Fig.9).
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Noboru NAKAI
Article type: Article
1985 Volume 73 Pages
103-110
Published: September 20, 1985
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When the product of hull efficiency, mechanical efficiency and relative rotative efficiency do not almost change by marine foul extent, the variation of propulsive efficiency is nearly equal to that of propeller efficiency. Therefore, the difference of effective horse power is obtained by using the propulsive (presumed) efficiency between two performance curves on the same propeller condition and shipspeed. Furthermore the increased roughness of hull is calculated by THE DIFFERENCE. As the trial of the ship installed CPP may be practiced with propeller revolution constant and pitch angle stepped up and η_h×η_r is nearly constant with hull condition, the curve on the condition of foul propeller and clean hull is simply and practically presumed from the curve of clean conditional performance before service and the frictional power of roughend propeller on service. The result was made sure with the shipspeed trials on propeller revolution constant. And the increased roughness of hull was calculated so that the values were 9.35mm in Oct., 1982, 2.41mm in Oct., 1983 and 0.27mm in Oct., 1984.
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Akira IWAI, Kuniaki SHOJI
Article type: Article
1985 Volume 73 Pages
111-116
Published: September 20, 1985
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Recently, ship collision accidents with bridges which span the main ship traffic route bring severe damage such as the case of the Sunshine Skyway Bridge (U.S.A.), Tjorn Bridge (Sweden) and so on. In order to avoide ship collisions with bridge piers, it is necessary to keep the ship away from the bridge pier initially. But if the ship enters the vicinity of the bridge pier owing its engine or rudder trouble, operator's negligence and so on, the bridge pier is necessary to be protected by some devices. In this paper, the authors studied the effectiveness the rope system protection. This system is consisted of horizontal wire rope and stanchions. A colliding ship is caught by horizontal wire rope and colliding energy is absorbed by elastic elongation of wire rope. This system is seemed to be useful for small-sized ship. The model experiment was carried out in the model basin of the Tokyo University of Mercantile Marine. The experimental result is good agreement with the calculated one in the case of right-angled ship collision. In the case of oblique-angled ship collision, some parts of the colliding energy is absorbed by the sliding of the ship along the rope.
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Keinosuke HONDA
Article type: Article
1985 Volume 73 Pages
117-124
Published: September 20, 1985
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This paper describes model tests on collisions between a ship and sloping structures and offers a useful method for estimating the ship stopping ability of the sloping structures. The two slope models, referred to as the hard slope (FRP plate) and the soft slope (shingle mound), were used to the model tests. As the first approximation on the estimation of stopping distance, it may be treated as the collision between the rigid ship body and the hard slope. And also, it may be able to replace the problem of collision against the soft slope such as the mound slope with that against a easy slope of hard structure. From the results of these model tests, author made sure of availability on the method for calculating the ship stopping distance of sloping structures.
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Sueo TAKASHIMA
Article type: Article
1985 Volume 73 Pages
125-133
Published: September 20, 1985
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It is well known that, when a ship is under way in heavy seas, large amplitude of the ship motions occurs consecutively a few times as well as large wave groups. In this paper, the number of consecutive large roll and pitch amplitude was discussed, by using the motion records of the previous report. The following results were obtained. (1) The distribution of the number of consecutive large amplitude can be calculate by the random theory. However, the observed values of the mean length and standard deviation of runs were slightly larger than the calculated values. (2) Observed probability of the occurrence of length of runs was clarified.
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Hideyuki NISHINOKUBI, Kiyoshi AMAGAI, Rihei KAWASHIMA
Article type: Article
1985 Volume 73 Pages
135-142
Published: September 20, 1985
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A study has been made in pursuit of the reasonable optimum fishing method or ship-handling method, based on the safety of the fishing boats in their operation, to cope with the sea conditions on the fishing ground such as wave height and wind direction. Analysis has been made by means of the multivariate AR model calculation as the dynamical feedback system while towing a trawl net, with the ship's motions as input and warp tension as output. From the frequency distribution of variations of warp tension and the power contribution, efficient trawling speed and distance between two boat trawlers could be determined. Therefore this approach is considered to be effective for the finding of the optimum fishing method.
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Hisashi MATSUMURA
Article type: Article
1985 Volume 73 Pages
143-149
Published: September 20, 1985
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Maritime Traffic Safety Law rules 11 traffic routes in high density traffic area and special conduct of vessels for scheming the safety passage of the vessels. Since it has come into force, in spite of repeated additional guidance in detail, noticeable marine disasters sometimes occured. In this paper, author investigated actual cases of ship's collision which occured in the traffic route and near the traffic route (within 2 n.m. from the boundary line of the traffic route). Then, considered conduct of vessels in each form of collision and pointed out some problems for safety passage of the traffic route.
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Saburo TSURUTA
Article type: Article
1985 Volume 73 Pages
151-155
Published: September 20, 1985
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The tensile fatigue properties of nylon ropes under cyclic loadings of constant amplitude were investigated. The test programme for unprotected single leg specimens was consisted of 3 parts. (1) Straight break test; this test was carried out to arrive at an average breaking strength which was thereafter used as the control of cyclic load. (2) Cyclic load test to failure; this test was carried out to obtain the relationships between failure life and maximum cyclic loads, and to compare this with that for the past data. (3) Cyclic load test to set number of cycles followed by residual strength test; this test was carried out to obtain the basic data of the strength reduction of nylon rope after cycling. Research on the residual strength of synthetic fiber ropes after cycling is seldom found, although researchs on the failure life of the ropes were studied. The followings have become clear by these tests. (1) Failure life; there has been no significant difference between the present result and the already reported results. Using the load expressed with the proportion to breaking strength, the result has been almost independent both construction and temperature, in the range of 10℃ to 30℃. (2) Strength reduction; there has been the indication of fall off in strength prior to failure. This result has agreed with Flory's hypothesis on the strength reduction of synthetic fiber ropes.
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Hisashi KUGUMIYA, Teruhisa FUJII
Article type: Article
1985 Volume 73 Pages
157-162
Published: September 20, 1985
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There are not a few records of accidents caused by wriggling ropes as they so behave when they are quickly strained or snap. Although the cases are generally serious, on account of their almost instantaneousness the motions of wriggling ropes have not thoroughly been clarified yet. We studied the phenomena using high speed photography. Our camera can catch the motions every 2.5ms, and we used the camera to get the bird's-eye view of the phenomena. The summary of the results are as follows: (1) each envelope, which is to be drawn connecting the extreme sideway deviation of a wriggling rope, has a particular character defined by its twist, (2) lengthwise speed of a broken rope depends on its Young's modulus, and (3) the flying speed of a snapped rope can be estimated by solving an simplified equation of motion.
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Masayoshi KUBO
Article type: Article
1985 Volume 73 Pages
163-172
Published: September 20, 1985
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In harbors influenced by waves, ship's cargo handlings are often interrupted by severe ship motions. The interruption threshold of cargo handling is, for example, 2 degrees of roll in amplitude, or 1 meter of surge or sway in amplitude. Furthermore, as the ship motions become severer, mooring lines of ships are broken and it becomes impossible to moor the ships at berth, and such a threshold condition of mooring is 5 meters of surge or sway in amplitude. In this paper, a new mooring system composed of dash-pots in mooring lines is proposed in order to decrease such ship motions. After some considerations, following results are obtained. Ship motions which are close to the threshold conditions of cargo handling can be decreased by using the dash-pots so that the damping force of the dash-pot is smaller than the strength of mooring lines and bitts. However, when the ship motions become the same order of threshold conditions of mooring, the damping forces exceed the strength of the mooring facilities. So it is necessary to strengthen the mooring facilities for the use of dash-pots in the storm.
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Tatehiko MIKI, Akio IMAI, Hiromiki FUJITANI
Article type: Article
1985 Volume 73 Pages
173-180
Published: September 20, 1985
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The loading of a number of small packages inside a freight container is one of the fundamental operations of containerization. Data consisting of inside dimensions of more than 17,000 containers have been analysed. The fundamental research in the formulation to obtain the optimal loading pattern was made, and two methods were shown of the determination of a loading pattern which makes maximum use of the inside volume of the container. One is a mathematical programming approach for packages of the same size, and the other a simulation approach for ones of various size.
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Sukita NAKAHARA, Yoshiro IMAEDA
Article type: Article
1985 Volume 73 Pages
181-190
Published: September 20, 1985
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The sways of human body standing on the rotating table with eyes closed were measured for movements of the body center of gravity by means of a statokinesimeter. The energies of the sways in each of the following 6 states (A)〜(F) were calculated from the measured RMS values of amplitude. That is, (A): 1min. before rotation, (B): during counterclockwise rotation, (C): 1min. after rotation (after disappearance of dizzy feeling), (D): 1min. before rotation after the rest of 2min., (E): during clockwise rotation, (F): 1min. after rotation. As the index of motion sickness susceptibility, the ratios of C/A, D/A, F/A, and E/B, and the average values of those 4 items were evaluated, where A is the energy of the sway in the state of (A), ……and F is that of (F). The average value was named motion sickness susceptibility index (MSI) by authors. The values of MSI were compared with motion sickness susceptibility scores (MSQ scores) which were determined by means of the questionnaire proposed by J.M. Lentz et al. (1977). The correlation coefficient between MSI's and MSQ scores was 0.857.
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Article type: Appendix
1985 Volume 73 Pages
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Article type: Appendix
1985 Volume 73 Pages
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Article type: Appendix
1985 Volume 73 Pages
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Article type: Appendix
1985 Volume 73 Pages
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Article type: Appendix
1985 Volume 73 Pages
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Article type: Cover
1985 Volume 73 Pages
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Article type: Cover
1985 Volume 73 Pages
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