For position fixing culculations by receiving data obtained from the Navy Navigation Satellite System (NNSS), it is necessaries to input some other data, such as ship's estimated position, ship's speed and antenna height to the data processing computer on board. If the ship's speed and/or the antenna height have some errors, ships position error will be introduced. This paper describes amplitudes of position error resulting from above mentioned erorr sources. These data was obtained from simulation calculations using practical satellite orbit data.
They investigated and examined a technique for the prediction of the receiving times of a Navy Navigation satellite by using the Escobal's Method and drew up a program for calculations by a mini-computer. In this paper they described the error of this method in about one year. They had about one minute error after a few month and about ten minutes error after one year.
The Loran C, [SS3], data of 1967-1971 were analysed as follows ; In the propagation route of Y rate over seawater, the constant deviations versus the distance from the master station were shown for linearly correlation, and the constant is ±3.2μs/100n.m. The deviation of X rate observed at Hiraiso was agreed with this constant in spite of the different area. The seasonal variation of the reflecting height was found at night and these stability was superior to that of day. The correlation between the field strength of X rate at Hiraiso and the 10μs jumps could not be found at the present time. Some modes of reflecting height in 100kHz were accordance with season, latitude and the direction of the pass route. If the SWC value is decided in fix, these variations will over the accuracy of this system frequently. Consequently, the Loran C SWC tables should be roughly correct by these condition above.
In the analytical process of manoeuvering chracteristics or numerical analyses of collision avoidance action, introduction of each bearings and distances of target into calculation formula makes so enomous combination of the situation that it becomes almost impossible to accomplish thorough and complete investigation. Authors, hence, contrived non-dimesional formulae as to distance and drew practical manoeuvering diagrams by the formulae. The characteristics of avoiding actions were also studied. Furthermore, the effect of mutual avoiding action, when two ships intend to manoeuvre according to these diagrams, were investigated and picked out desirable manoeuvering patterns of collision avoidance.
The port and starboard discrimination device is composed of a marine radar with some adaptor and a simple receiver. The system of the device is undermentioned ; (1) The port and starboard discrimination is limited among the ships with this device. (2) p.r.f. is changed when scanner pass over fore and aft line. (3) The receiver accepts this change of p.r.f. and discriminate port and starboard of another ship. Foundamental field tests at sea were performed between "Taisei Maru" and "test boat", and the effect of the device was confirmed. The tested device has some shortcoming, however, the authors believe that if the defects of this device are improved, it may contribute to collision avoidance.
It is difficult to detect a small target on sea surface for a radar. If a target is active, even though it is small, a radar can detect it easily far away. The radar bouy is a socalled tranpender which receives a radar wave and transmits a UHF signals. Now-a-dys, it is used generally to find fishing nets. The coverage of radar bouy is calculated about 11〜12 miles theoretically, but fisher men say that actual range is about 5〜6 miles, sometimes 4 miles or so at sea. Authors experimented evaluation tests for several times at sea and found the causes of shortage between the theoretical coverage and the actual. After some improvements for the equipment, good results were obtained.
The plotting by the use of Radar is essential to collision avoidance as its practice has been adviced by IMCO. "Radar Tracking and Plotting Equipment" which plots automaticaly by means of electronics has bee successfly developed. This equipment consists of data proccessor and IC memories. Using conventional shipborne radar, it is able to plot five points of the passed track of a target ship automaticaly on the radar plan position indicator. Farthermore, it is able to choose the most safty maneuvering by the use of trial maneuvering computer system when the risk of collision was found. This paper describes the design and principle of this equipment, and also the experimental result that has been obtained on board for these one and a half year. On the basis of this result, they concluded that plotting is available under rough sea condition and heavy sea clutter. It was also concluded that the principle of trial maneuvering has been established with this equipment although this has a few mechanical week points.
The chemical and electrical characteristics of moist recording paper for echo-sounder was already studied, but color measurement for step input voltage was not yet taken. So we measured tristimulus values (X_2, Y, Z), and plotted Y curve, x-y chromaticity diagram and color difference curve. According to color measurement for five maker's recording papers, we found their characteristics were nearly equal.
This model experiment was carried out by means of the experimental water tank with windtunnel at Tokyo University of Mercantile Marine. Objects of this study are to get some basic knowledges for developing more suitable mooring methods. Cases and conditions of experiments are as follows: -model ship: 2.00m model of Japan Margarett (D.W. 242, 000t) scale 1/150 ship's condition: Normal ballast and half load condition even keel wind velocity: 25m/sec and 35m/sec in actual ship, but without wave. wind direction: every 30° in all round, 0° is head wind. mooring arrangement: A type conventional type, made up with fore and aft lines and spring lines B type New type, made up with breast lines and spring lines water depth: 21m in actual ship Some results of this experiment are as follows. 1) Without waves, it may be possible to moor large tanker to offshore dolphin in strong wind less than 35m/sec. 2) We can not recognize necessarily that the conventional mooring method is the mostsuitable method. In this experiment, the new method is more suitable than the conventional one. 3) In concern with tensions on mooring lines and loads on dolphins, measured values in experiments are nearly correspond to theoretically calculated values in statical analysis.
The author published in 1968 on the course stability of SHIOJI MARU, the ship of Tokyo University of Mercantile Marine, and alluded in the report to the effectiveness of a fin fitted above the rudder to her course stability. As the fitting of the fin was not sufficient to remove unstableness, they renewed the rudder which has the rudder ratio A_R/L・d=1/32.3, in comparison with the old one of 1/38.4. After several tests of maneuverability, renewal of the rudder remarkably contributes to improve maneuverability indices, and yet unstableness is not removed. Merely for improvement of course stability at straight course, fitting a fin having suitable area is prefer to the renewal of the rudder.
This experiments were made for the purpose of investigation to audibility of ship's acoustic signals. The following became clear after the experiments with the trial acoustic generator. (1) At the distance within 1 N.M., the attenuations of propagation are constant to signal's frequencys from 100 to 700Hz. (2) The attenuations at upwind are proportional to the sixth power law of distance. (3) The attenuations at downwind and crosswind obey geometric diffusion. (4) With aim at audibility above 4 N.M., the required sound pressure level (a point of 20m) of acoustic equipments is more than 120dB, and its frequencys are from 300 to 400Hz.
The purpose of this study is to optimize the total physical distribution system, and so the authors built the system model of inland to port transportation of exporting general cargo, which consists of 7 inland routes combined with road, railway, barge transportation and warehouse. And the physical distribution costs were calculated through computer simulation. The results of study, which should be managed for the sake of reducing the P.D.C., were as follows: (1) There is the optimum combination of elements affected on P.D.C. to handle the cargo flow efficiently. (2) The percentage of port facility's cost against total P.D.C. is 56.4〜37.7 and ship's cost is 41.5〜9.4. So the P.D.C. is influenced extremely by these two elements of cost. (3) The ratio of cargo via apron should be increased together with simplification of inland route. (4) The utilization factor of berth should be kept between 0.60 and 0.88.
The solar radiation intensity and the air temperature and humidity inside and outside a closed dry container were observed at the campus of Kobe College of Mercantile marine in Kobe city on 3rd. (cloudy), 6th. (rainty) and 7th. (sunny) Aug.1971. Some results are as follows ; (1) It is important to find out not only the meam value but also variations in temperature and humidity which vary with in order to know the weather situations in detail, to protect the cargo from sweat damage and to design a good container. (2) On the above three days the mean value of the transmisivity. P of solar rodiation through the atmosphere and the ratio of the observed solar radiation intensity to the theoretical one J_n/J_<n, th> are (0.65, 0.53 ; 3rd (cloudy), (0.35, 0.18 ; 6th (rainy)) and (0.75, 0.65 ; 7th. (sunny)) respectively, so, it is cleared that humidity (specially clouds) bas stronger injluehce on P and Jn than pure air and the duet in the atmospbere. (3) They proposed to use a statistical method with a certain distribution curve which deals with the mean value and variation of the time-varing temperature and humidity, and want to note there are two types of distribution: one is a wide range and the other is a narrow one, for the weather situation the former means a changable weather, the latter does an unchangable one, besides for the rang tempemperature the former means the change of outside face temperature t_f of one container, the latter does that of ambient air temperature t_o outside the container (4) For the temperature response at some point of container, the variation of t_f is about five〜ten times of that of middle portion temperature t_4 in the contaiher, and the peak of t_4 follows on that of t_f with a lag time of about 15〜20 minutes. (5) They want to point out the following two indices which are useful for the purpose of optimal route and package to minimize sweat damage and to do quality control for the corgo ; (i) total hours (t_f is below t_4) of the day…ΣΔt_<f4>/24 because in the former period Δt_<f4> (ii) tolol hours (t_f is below the dew point d_4 of the air in the container) of the day…ΣΔt_<fd>/24 because in the former period Δt_<f4> condensation is expected to happen in the container wbose outside face is wetten, in the latter one Δt_<fd> condensation and wetting cargo actually happens in the container as t_f is usually decreasing at sunset.
The more the container transportation increases, the more knowledge of the character of the container vessel will be important. So, in this paper, how the change of the outdoor temperature effects to the inner one is investigated. By using the one-dimensional model, the thermal differential equation is solved with the difference method. Thus, the obtained result is compared with that of the experiment which was made previously. Then the coefficients and parameters are changed to make this thermal simulation model of container vessel proper. Then, the simulations, whose experiments are difficult to carry out under various conditions, were made and proved useful. Main results are summarized as follows: (1) In addition to the equation by Schmidt method, the equations which are based on the assumption that the temperature varies uniformly in steel board and air domain of container vessel is used. The result by these equations considerably fit with those by the experiments. (2) It is possible to be treated approximately as one-dimensional model for heat transmission. (3) The sheltering effect of heat by the container walls depends on the amplitude and period of the outdoor temperature variation.
Temperature and humidity of inside and outside of a model container (80×80×200cm in dimensions) are measured. Obtained results are as foollows: (1) Relative humidity in a closed dry container is controlled almost of the same values by evaporation or absorption of water vapor from the side board and the floor board. (2) It is possible to remove moisture from the air inside the container by means of ventilation. To increase the ventilating speed, it is necessary to improve the methods of stowage of cargo. (3) The moisture content in the container also considerably increases by the stevedore's long time work for loading. (4) Possibility of sweat damage increases by the evaporation of moisture from the carton wet by the rain. (5) Quantity of evaporated or absorpted water vapor from the side board and the floor board is estimated in both case of a closed container and mechanically ventilated one. (6) For protecting sweat damage in a dry container, the side board and the floor board must be dry as much as possible, and moistureless cargoes and packages are desierable. The vapor pressure in equilibrium moisture condition of cargo must be kept lower than that of the inside air of a container under the condition decided by the heat transmission in the wall of the container, the route of the ocean voyage, the season of the voyage and the sorts of the cargo.
In Japan there are 243,595 power-driven fishing boats under 20 G.T. (of which 13,827 boats in Mie Frefecture). On Kumano Nada, many of these fishing boats are at work close by the fairway of oceangoing ships. Especially vessels which sail into and out of Ise Bay come into contact with them in the vicinity of Cape Daio. In order to examine their actual conditions, I surveyed 105 fishing boats in 1971 which are registered in Anori, Kamisakinra and Hozaura Fisheries Cooperative Associations, Mie Frefecture. About these boats I reported in this treatise on the equipments (magnetic compass, radio direction finder, echo-sounding machine, loran etc.), speed, horsepower of engines, fishing grounds, licence of skippers, number of crews etc.
The distribution of the ships anchored against the typhoon in Osaka Bay from 1967 to 1970 is investigated. The types of distribution is divided into two types. When large and strong typhoon looks like to attacks at Osaka Bay, the ships at anchor distribute uniformly, but they distribute rather crowded in the north prat of Osaka Bay when the typhoon is small or the course is far away from Osaka Bay. The distribution of the distance between two ships is also investigated. The number of the ships at anchor against a typhoon increased year by year. In a few years, we will hardly be able to find the surplus of anchorage in Osaka Bay.
Using the picture angle of single camera photograph taken by 30 seconds or 1 minute intervals, and from the view screened calculate the ship's length, speed and arrival interval, and detect the speed frequency distribution of each ship's length and chracter of poisson arrival distribution of ships in each channels.
The author showed that marine traffic flow is like to compression wave caused by the difference of speed between ships in the flow. It is devised a conversion methed of a compression wave phenomenon into a contiuous wave phenomenon using density potential defined by him. It is concluded that compression wave-like characteristic is depend upon the density of a certain area and the variation of speed distribution.
Number of researches related to the traffic volume of ship in various seas and straits of Japan and observations of the behaviour of the passing ships have been reported these several years. The Akash Strait studied here is located on one of the most important maritime traffic routes in Japan. The recent exploitation of the Seto Inland Sea area has much increased the traffic volume and complicated the passing course of individual boats. As the first step of the forecasting study, the present paper described the recent trend of the traffic volume in the strait basing upon the various economical indices and records during the period 1963-1970. The procedure is summarized as follows: (a) Export (valued in milliom dollars) <EQ.1>___→Export tonnage (in 1,000 tons) <EQ.3>___→Number of foreign trade liners (Japanese) <EQ.2>___→Number of liners (foreign and japanese)→Number of liners cross-ing the Akashi. (b) Import (valued in million dollars) <EQ.2>___→Import tonnage (in 1,000 tons) <EQ.4>___→Number of foreign trade tramps (Japanese)→Number of tramps (foreign and Japanese)→Number of tramps passing the Akashi. (c) Tons of domestic cargo crossing the Akashi <EQ.5, 6, 7>___→Number of passes of domestic cargo boats through the Akashi. (d-1) Number of road motor vehicles in Japan→Number of motor vehicles of nine prefectures facing the Seto Inland Sea <EQ.8>___→Number of passes of ferry boats through the Akashi of ferry boats (d-2) Number of passes of domestic passenger boats and hydrofoils. (e) Number of passes of fishing boats. (f) the total of (a) through (e) gives the estimated annual number of passes of vessels through the Akashi, eastward and westward, respectively. As a result, the 1970 year value of traffic volmue the 1975 year value were expected to reach 148 per cent and 408 per cent of the average 1963 year value of observed traffic volume (1200 per day), respectively.
A survey on the marine traffic accidents is made for a period from 1966 to 1969. A grand total of 17,626 collided vessels is divided into two categories, namely, collisions in harbours (71%) and out of harbours (29%). Following items are investigated: (1) seasonal variation, (2) diurnal change, (3) distribution in ship size, (4) degree of damage especially on the relation of ship size and damage and (5) encounter condition. The main purpose of the study is the mapping of collision locations accompanied with information of ship size. Results show that the accident black spots are densely populated in the so-called Water Megalopolis around which most of Japanese factories are established.
The estimation of collision number for a ship passing through a certain water is often requested. The first approximation of this collision number can be easily obtained as the product of (L/L_0) and the coefficient, F, mentionned in the title, where L is the length of the ship between perpenPiculars and L_0 is equal to 32m. The coefficient is defined as the number of collided ahips in the water range in unit time divided by the traffic volume summed up using (L/L_0) as the weighting faotor. The coefficients for important harbours as well as several congested straits are given and compared in a figure. An interpretation of the coefficient is tried placing Fujii's equation at starting line. Result of analysis gives the method of adjustment for minor change in the traffic volume in the water range being considered.
Author proposed a new method on the estimation of the probabilities of collisions of ships passing through any fairways with confused marine traffic, applying the queing theory to marne traffic and ship maneuvers. Ships are used to pass through fairways making various kind serveices such as maneuvers for altering coarse or avoiding collision to other ships and obstacles. The records of heading angle of two large tankers passing through the Singapole Strait and the Inland Sea in Japan were analyzed to get the statistical characterintics of ship's manurvers. The results show the following two points, (1) arrivals of other ships and obstacles which require services are randamon (2) the distribution of service times is nearly negative exponential. Therefore, the stationary probability of collision can be estimated by the following equation based on the queing theory P=ρe^<-μτ(1-ρ)> where: P: probability of collision ρ: the ratio of λ to μ (Collision Avoidance Intensity) λ: mean value of arrivals per unit time μ: mean value of serveices per unit time τ: limit of waiting time. The probabilities of collisions of ships passing through the Uraga strait were caluculated by this method. The values of λ, μ and τ were reasonably estimated based on the many reports of marine traffic engneering. The results of calculation were compared with the statistic value of collision and stranding there in the last ten years and the agreement between them were found to be good except for small vessels. Therefore this method is applicable to evaluate the validity of regulation and control on fairways and the imporvement ship's maneuverability on the point of the safe navigation.
Many ships encounter heavy severe sea states in the northern Japan, especially near Hokkaido. When the sea state can be predicted, ship operation and maneuvering become safer and sea casualties will be decreased. For this purpose, this paper presents the numerical sea state calculation method on the Strait of Tsugaru, between Honshu and Hokkaido, and discuss the difference between the observed wave heights obtained by the suspended type wavemeter and the calculated values previously obtained. Moreover, the methods to obtain the wind direction and force in the strait are shown by using the track and the pressure of the center of a cyclone.
As to the nooring and maneuvering of a ship in harbour, the ship's motions induced by the sea waves in harbour were calculated and discussed from the view point of the statistical analysis of random process. Concerning the measurement of wave heights in Hakodate harbour, the wave heights were measured, simultanously, by the use of a step type wave measuring pole at 4 points of observation stations which are shown in Fig.1. On the records of wave heights of these stations, the power spectra were calculated and are shown in Fig.2. From the wave spectra in Fig.2, it is found that the breakwaters of the harbour have a characteristic as a high pass filter for sea waves. As the example case of a ship's motion in harbour, the author calculated the ship's motion spectra by the relation of epuations (1) and (2) on the coupled heaving motion. The result of the calcualtion in shown in Fig.4. Based on the calculated motion spectrum, the extreme value of motion was calculated and discussed.