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Article type: Cover
1979 Volume 60 Pages
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Published: February 20, 1979
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Article type: Cover
1979 Volume 60 Pages
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Published: February 20, 1979
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Yurin SAKAMOTO, Takashi HIRAIWA, Kunisaburo YONETA
Article type: Article
1979 Volume 60 Pages
1-11
Published: February 20, 1979
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The purpose of this study was to examine the peculiarity of the Omega phase difference all round a fixed location. We measured the phase difference of the A-E, C-E, D-E and E-H pairs every 30 minutes at the Faculty of Fisheries of Hokkaido University from January 1, 1977 till December 31, 1977. The phenomena can be analyzed by Fourier's analysis of the propagation correction every half-month. We determined the amplitudes a_n and phases β_n from the following equation: [numerical formula] When the Omega signals passed through an all daytime path, both the E-H and the C-E pairs showed a small standard deviation around the mean values of every one hour measurement, but the others did not show a distinct difference in connection to time variation. As to the steadiness of the phase difference, the E-H pair was better than the others, but the accuracy of position was not satisfactory because of the smallness of its included angle.
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Kunisaburo YONETA, Seiji SASAKI
Article type: Article
1979 Volume 60 Pages
13-19
Published: February 20, 1979
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Ships equipped with the OMEGA navigation system, have been increasing these recent years. However, the evaluation of a given position in this system, is still not fixed. The authors measured OMEGA signals of C-H, D-H and E-H pairs on the going and returning voyages between Japan and Australia from the 15th of January till the 10th of March, 1978. The results were as follows ; (1) On the received condition of OMEGA signals, the E-H pair was fine during all coverage, but the C-H and D-H pairs were worse while going southward, especially, the C-H pair was the worst at nighttime in the South Pacific Ocean. (2) The fixed position by C-H and E-H pairs have comparative stability and confidence in daytime, but they have no stability and confidence at nighttime and an hour around sunrise and sunset. (3) A user must be careful about the included angle based on the direction from OMEGA stations, because fixed positions have large errors in the area of a small included angle, even if the OMEGA signal can be received in fine condition.
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Kazuo TAGUCHI
Article type: Article
1979 Volume 60 Pages
21-28
Published: February 20, 1979
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The characteristics of the cycle jump (rapid phase change in one cycle unit) in the OMEGA signals were studied with the three years observations in Japan during the years from 1975 to 1977. Statistical results of OMEGA signal gave the many useful information to improve the navigational accuracy. These studies will be revealed as follows: 1) According to the general features of every signals, cycle advance occurred in both sunset transition and nighttime, and cycle slip in sunrise only. 2) Occurrence number of cycle jump of OMEGA Hawaii slightly increased in accordance with the receiving site moves to westward in Japan. For example, occurrence percentage in the year was 1% in Tokyo and 6% at Hiroshima. To the contrary, the results obtained in the southern district were highly notified as compared with ones in the northern district above mentioned, that is 22% at Kagoshima and 33% at Okinawa. Consequently, the 10.2kHz OMEGA Hawaii in Japan should be comfirmed for usable range in magnetic latitude 25゜, geographic 3.5゜. 3) No cycle jumps in both 10.2kHz and 13.6kHz at night during April to October through the observations. Moreover, in 10.2kHz, cycle jump in the transit time showed the annual change. 4) The signal of OMEGA Norway and North Dakota propagated through the high latitudes do not showed any jumps in Japan except Kagoshima.
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Hiroshi Suzuki, Etuyuki Hamada, Yasuyuki Shirai, Koh Hatano, Kiyotaka ...
Article type: Article
1979 Volume 60 Pages
29-36
Published: February 20, 1979
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This paper described about the design and performance of a digital magnetic compass sensor which is fitted on a commercial magnetic compass bowl. The digital magnetic compass sensor is a dry card slave compass having double pivots and an eddy current damper. A gray code pattern, printed on the dry card, passes the light ray from small lamps just fitted above the card, and nine CdS receivers offer the gray code singnal to a ROM which converts the gray code address to a seven-segment-course-indicator. The slave digital compass indications, following the master compass were measured by simulation that solved two non-linear differential equations simultaneously by using Runge-Kutta-Nystom's method. And the experimantal results showed that the values during the damping movement of the digital compass were in good coincidence with those of the simulation. These results would also provide a digital signal of ship's course to NNSS system for its interpolation calculation of position on the ships without the gyro compass.
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Shogo HAYASHI, Yukito IIJIMA, Matsutaro SHIMOYAMA, Toshihiro SUGIYAMA
Article type: Article
1979 Volume 60 Pages
37-44
Published: February 20, 1979
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A Radar Aspector which is a equipment to instantly identify aspect angle of another ship concerned was reported before. It could be greatly advantageous for navigators to avoid collision. In this paper, the new type of the Radar Aspector is described. This equipment can provide of manoeuvring information such as course, speed and another information. The equipment utilizes interval time of digitally encoded pulse of radar. For example, each group of intervals corresponds to specific meanings such as ship's course, speed and so on as the following table. [Table] If a ship receives following sequence of pulse interval from another ship's radar, 1, 001μs, 1, 010μs, 1, 023μs, 1, 006μs and 1, 034μs, these are decoded as course 103゜and speed of 24K't. The theory, the fabrication and the results of experiment are reported in this paper.
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Hiroyuki YAMANOUCHI, Yahei FUJII
Article type: Article
1979 Volume 60 Pages
45-49
Published: February 20, 1979
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The danger of traffic accidents for a ship passing through a water was surveyed previously for 1966〜1968 at major channels and harbours in Japan. Since the environment of marine traffic has been changed to a certain extent, comparison is tried for two sets of figures ; 1966〜1968 and 1973〜1975, obtained by the similar survey and analytical method. It gives the tendency of decreasing danger of collision in straits except one. Comparison of collision danger in harbours is not sufficiently made since previous data include collisions with piers, wharfs, etc. However, these data, we expect, will be used for such survey in the future.
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Shintaro HIRANO
Article type: Article
1979 Volume 60 Pages
51-60
Published: February 20, 1979
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When a vessel tries to cross a route, she seeks a gap in the queue of the vessels in the main route by means of collision-avoiding maneuver. As the result of this operation, that vessel turns her position to the right. In the narrow sea, the maginitude of this shift (Td) is the most important factor in determining the traffic capacity at the crossing. A certain equation can be established between Td and Tw, i.e., the relative waiting time, which is represented by the same formula as is used for the waiting time in crossing a road on land. Therefore, in case Tw is given, Td can be obtained. However, when the traffic is congested, the vessels in the main route form a number of queues and also the collision-avoiding maneuver of the crossing vessel varies according to the mutual relation among the vessels in the several queues formed in the main route. Therefore, in such a case, it is difficult to obtain Tw by the theoretical formula. In this paper, the solution is sought by means of Monte Carlo Method ; the probability curve of Tw is presented ; and the nature of this solution is discussed. Besides, Td is calculated from the result of this solution ; the value thus obtained is ascertained to be very close to the value actually observed at the crossing ; and examinations are made on the traffic capacity at this crossing.
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K. Ohtsu, S. Hamma
Article type: Article
1979 Volume 60 Pages
61-72
Published: February 20, 1979
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In this paper, the authors tried to represent the manual or autopilot steering regulation by an autoregressive model. At that time, the order of the autoregressive equation was determined by the well-known minimum AIC (Akaike's Information Criterion) procedure. To conclude, it made clear that our stochastic model could describe precisely the steering regulation and moreover we could point out that it was rather disadvantageous in energy consumption of a steering gear that a small vessel armed with the autopilot having the differential (rate) control function.
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Susumu Kuwajima, Hiroaki Kobayashi
Article type: Article
1979 Volume 60 Pages
73-82
Published: February 20, 1979
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The property of wind turbulence on time history and it's effect on ship's motion have been reported at part I last year. In this paper, the space distributions of wind turbulence which are obserbed at open sea and experimented at laboratory, and the numerically simulated ship's motions according to that wind turbulence are described. As the result, standard deviations of relative wind speed σ_<*ν> and relative wind direction σ_<*θ> between two observation points which transit line is at right angle to the main wind direction are respectively estimated by σ_<*ν>=0.15V (m/s) σ_<*θ>=0.785V^<-3/4> (radian) at open sea. The space distribution of wind speed behind the structure wholly depend on the shape and size of structure. On the other hand, the simplified estimation method of wind force which act on ship's hull located behind structure showed good consistency with experimental results. The effect on the motion of ships which make way behind the structure is found to become large if 1) the size of structure to ships length is big, 2) the distance between ship and structure is short, 3) the ship's speed is small, 4) and the wind speed is great.
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Hiroaki KOBAYASHI, Masanori KISHIDA
Article type: Article
1979 Volume 60 Pages
83-91
Published: February 20, 1979
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A ship equipped with controllable pitch propeller (CPP) is superior in her stopping ability. But, when she is going to stopping or reducing her speed, her manoeuvrability is inferior to ships with fixed pitch propeller (FPP). We think the difference is due to the inflow velocity to the rudder. So we had investigated the normal force of rudder behind CPP at a circulating water channel. And the results are given as follows. 1) On a CPP ship, decreasing his pitch, Negative slip ratio area comes out and the rudder behind the CPP will perform in a lower velocity field than propeller advancing speed. So the normal force of rudder is smaller than a FPP ship's. Especially, when the blade angle is equal to zero, the rudder force is almost equal to zero, 2) We got a experimental formula to calculate mean inflow velocity of rudder for a wide slip ratio area. We suppose that mean inflow velocity of rudder for any slip ratio can be calculated from general momental theory, and the amend-mental coefficient K of the theoretical equation should be shown as a quadratic equation of slip ratio.
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Kinzo INOUE, Keinosuke HONDA
Article type: Article
1979 Volume 60 Pages
93-107
Published: February 20, 1979
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Authors carried out the model experiment for detached mooring in beam sea at deep water in the case of 5, 000G.T. cargo ship in order to find a means of feasible and safe mooring in the harbour under heavy weather. The main results for the model experiment under the condition of regular waves are as follows: (1) The symmetrical elastic force of mooring lines at the detached mooring produce slight swaying amplitude and no subharmonic motion in comparison with the quay mooring under the non-symmetrical elastic force. (2) In the case of detached mooring at the solid wall, swaying amplitude, swaying drift and tension load on mooring lines can be kept comparatively slight, when the center of gravity of the ship is located right in the middle between the node and the loop of standing wave which is formed in the vicinity of the solid wall. (3) It is considered that the detached mooring at the dolphin is rather effective than at the solid wall because of reducing the amplitude of ship motions and the tension load of mooring lines, in the case that the wave length of incident wave is over 4.5B (B: ship breadth). (4) When the surface of the water rises over the top of the quay wall at the time of high tide, the effects that the ship motions are kept slightly at the detached mooring at the solid wall are reduced. It would be desirable to take the detached mooring in the harbour under heavy weather for the benefit of reducing the amplitude of ship motions and the tension load of mooring lines.
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Kazumi TANE, Yoshinari OKANO, Kiyoshi TOGARI, Isamu OHSUGI
Article type: Article
1979 Volume 60 Pages
109-115
Published: February 20, 1979
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Synthetic fiber rope has recently taken the place of manila rope on board the sail training ship "NIPPON MARU" as sailing gears, because of its light weight, easy handling in rain and low-price advantages. We have experimented with the remaining strength of two kinds of Polypropylene ropes and manila rope after using one year or more as braces and halyards. P mono (mono-filament one) P mult (multi-filament one) The results are as follows. 1) P mult and P mono are excellent as halyards 2) P mult is better than the others as braces. 3) We may use P mult and P mono as sailing gears about two or two and half years which is about the same life of the manila ropes. 4) We must take care of the elongation of above synthetic fiber ropes for the safety of works and must not use them as gunt lines, cat falls, boat falls and so on.
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Yoshio Murayama, Yasutake Nishiyama
Article type: Article
1979 Volume 60 Pages
117-123
Published: February 20, 1979
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The authors have determined the distributions of concentrations of toxic vapours which are evaporated and diffused in a model of ships hold. They got the results that the concentrations of toxic vapours at the height of 0.5〜1.2m in a closed air space become high levels comparing with another places and that the average concentration at the height of 1m(C_<z=1>) is given as follows: C_<z=1>=(10.17-8d)0.018×10^3 Where d=1+P_<max>(M/29-1)/760 P_<max> : Pressure of satulated vaper M: Molecular weight The formula which is expressed a vapour hazard index with transport phenomena (VHIT) based upon the concept of the toxicity by threshold limit value (TLV) and the C_<z=1> above mentioned will be given as follow: VHIT=C_<z=1>/TLV
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Article type: Appendix
1979 Volume 60 Pages
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Published: February 20, 1979
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Article type: Appendix
1979 Volume 60 Pages
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Published: February 20, 1979
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Article type: Appendix
1979 Volume 60 Pages
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Published: February 20, 1979
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Article type: Cover
1979 Volume 60 Pages
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Published: February 20, 1979
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Article type: Cover
1979 Volume 60 Pages
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Published: February 20, 1979
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