Since the announcement of the laser in 1960, there has been considerable activity in the reserch, development and application of the laser. The laser suggests much possibilities to greatly make a contribution to technical, medical and many other fields. The purpose of this paper is to describe the theory of the laser simply and to mention some applications to navigation.

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A number of fishing gears are customarily set in the coastal waters of Japan. For the safe navigation, accordingly, the Maritime Safety Board of Japan checked up the settled locations of the large-sized fishing gears, and announced the results in "Chart showing the position of set net fisheries". But, in order to pass well clear the fishing gears especially at night, the navigators are obliged to use some subsidiary instruments such as radar because the fishing gears have no light. The dolphin bamboo shelter (SHIIRAZUKE) settled in off-shore is typical fishing gear of probable obstacle to navigation. Many bamboo shelters are settled in the Japan Sea, mainly in summer and autumn, for gathering the scattered individuals of dolphin through their negative phototaxis; and it is very hard to find out these shelters by naked eye at night, although it is rather easy in the daytime. Basing on a series of the observations on the target of the shelter on the radar scope, the author gave some descriptions of the characteristics of the radar picture from the navigator's point of view and discussed statistically the maximum detectable range. The results obtained are summarized as follows: (1) The dolphin bamboo shelter can be detected by radar, although it is small in size and poor in reflective efficiency. (2) The target appears obscure and very small, when the gain control has been adjusted to normal value and range scale to medium one for normal navigation in open waters. And a somewhat higher setting of the gain control on lower range is suitable for making the targets stand out clearly. (3) The frequency distribution of log(2.0-R) follows normal one when "R" represents the maximum detectable range. (4) The average of the maximum detectable range is found to be 1.1 miles with considerable variation. (5) On the scope, the range of finding out the target is 0.2 miles (about 20%) shorter than that of losing sight of it.

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With the lapse of time since the dry docking, ship's bottom becomes dirty and the zinc plates chip by corrosion. So the pressure log, generally installed on the ocean going ship, becomes to have error on the speed indication by the static pressure fluctuation. The author made models of ship's bottom attachments and zinc plates deformation with rectangular plates and cylindrical plates, and made experiments in the wind tunnel jet stream. When one of the ship's bottom attachments lies alone, the ship's Euler number is about 1.2 times as large as one gained on the wind tunnel experiments, but when several shaped attachments exist and they interfere one another the quantitative elucidation is difficult. To exclude above initial error of the pressure log the author advocates the three holed Pitot tube.

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The "Japanese Committee for Radio Aids to Navigation" has been making "Inquiries about Radars and Radio Equipments for Navigation" into ship's captains and officers on the sea, from 1959 to 1964. For this aim, 1, 500 of printed matters were used, and got 147 reports. In this paper, the author treated only for the problems of the Radar images which were reported in those inquiries, First, he investigated about 110 examples of reported problems concerning with radar images, such as squalls, sea clutters, distinguishing between images, difficulties of fixing of ship's positions and about special images. Second, he investigated about the special districts in the world, where has been found unusual phenomena, such as superrefraction in Gulf of Oman, Persian Gulf and the westside of Australia, etc., sand storm images at Ras al Hado of Arabia, too much false echoes in the Islands of Philippine, etc.. Third, he investigated about the real condition of Japanese merchant officer's radar plotting procedures, and he recomends to make a stronger education about the radar plotting and collision avoidance by radar, for the navigators in Japan.

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To get a more accurate position lines on the rotary beacon system, we tried to make a device which contains a pen-recorder. The device has taught us through an actual experiment that the system can be more useful because of the visible signals on the recorder. Though there are still many problems left unresolved, we also could learn through the experiment that they are convertible. So this work will be continued to be realized as a practical device on this system.

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It has been well known that the time differences of Loran ground wave of Loran table are not seemed to contain the propagation errors. Therefore we can fix Loran ship's position by Loran table. However, it has been reported that measured values often largerly vary with every measuring. I measured Loran rate 2 H 3 and 2 H 4 in the southern waters off Kyushiyu, I obtained the following results by these observations. 1) When the propagated route of Loran wave is only sea-surface, in the area 50' distance from master station, the error obtained is 1.3μ sec. (in average of 30 points). It may be suggested that above mentioned errors are rather due to the speed of electric wave faster than that of Loran table computed. Moreover I pointed that the base line of 2 H 4 coincides the stream line of "Kuroshio". 2) Loran wave transmission over land gives lower velocity comparison with standard velocity from Loran table.

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The author measured the performances of the echo-sounders, each 14kc. and 200kc. in frequency of 2 sets and both frequencies of 1 set under sailing in shallow and deep sea waters. From these data it may be considered following results. 1) It may be supposed that the margin curve of the echo-sounders obtained in shallow waters cannot apply into the curve of deep waters. 2) The distance between echo-sounders and keel line is larger, more attenuations by propellering is increased. When the sets of echo-sounders installed in near middle sectons of the hull, one fitted from 1.25 meters from the keel line, another is 2.20 meters, the latter gives larger attenuation than the former by propellering and the attenuation-difference is about 20 db. 3) Clear differences were obtained on the relations between installed positions and relative wind direction in the performances of the echo-sounders.

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By the means of the method described in the former paper, the characteristic response of the ship's motion among ocean waves was estimated and discussed on the basis of the record of the actual ship experiments in the seaway. In the experiments, when ship stopped her engine and drifted among the waves, wave heights, angles of roll and pitch were measured and recorded by the wave pole with telemetering apparatus and Gyro type roll and pitch meter, respectively at the same time. The numerical data reading from these records, taking each constant as Δt=1sec, h=45 and M=318, the calculations were performed. The results were shown in Figs.3, 4 and 5 Where; Δt: Time interval between adjacent data values h: Number of lags of correlations used for the computation of the estimates M: Number of data used for calculations

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Chart No. 6011 "Symbols and Abbreviatins used on Japanese Nautical chart" was published in 1957 according to the Standard List of Symbols and Abbreviations based on the Repertory of Technical Resolutions issued by the International Hydrographic Bureau (I.H.B.). Since then, as the Repertory was revised and its contents have been renewed, our chart 6011 had to be revised accordingly. Thus, we are now working to revise it. The principle of this revision is to adopt I.H.B. symbols as possible as we can. The author here shows the type, arrangement, contents and index of the sheet, together with some actual examples of the new symbols adopted.

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The author derived the method to obtain the observer's position by observing the Doppler shift of radio waves transmitted from artificial satellite. He showed the example of calculation about the satellite Transit 4A revolution 13, 449 observed at Koganei, Tokyo on Feb. 24th, 1964.

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The new celestial navigation utilizing the artificial satellites is likely to be realized in near future. Considering the above conditions, I investigated the following two fundamental problems needed to locate these satellites in three-dimentional space. (1) The orbital elements and their computation. (2) The required coordinate systems and their transformation.

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In regard to the difference of distance between Great Circle and Rhumbline, which we call Saving of Distance, we considered of the condition to give the maximum value to Saving of Distance when Great Circle Distance is constant. And, we found the condition is ψ≒λ, where ψ is the Lat. in and λ is the D. Long. During the study, we contrived following formula for approximate meridional parts. That is: -ψ'^3=ψ^3secψ where ψ'is meridional parts of the latitude ψ.

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The paper described on a result of the investigation into the actual condition for routing traffic in Akashi Strait that the execution are under way for the Cross Channel Bridge Scheme. The flow of small vessel (under G. T. 1, 000t) that amounts to 95% in the total traffic volume were distincted by means of the Radar Photogragh and the Observer's Sketch.

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Authors made up a new fluke style stockless steel anchor, design of which based on the results of comparative serial model tank tests experimented on the shape-effect of anchor upon the holding character. The holding power to anchor weight ratio for new steel anchor has about 8 times or more than that of JIS-stockless anchor in model same tests, it may be thought a success as the trial production. However, having design for the full-scale anchor, it is necessary to investigate on mutual relation between sea-bottom soil and anchor weight, etc.

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The causes of ship's side-drifting are the force of wind on the upper structure of the ship, drift current increasing with the wind, rolling caused by wind wave and swell, and the ocean current and the tidal current. To search for the effect by wind action on the side-drifting, one of the above causes, it is necessary to make an experiment which is possible when removing the effects by the other causes. The authors planned to measure the side-drifting way with parameter V (speed of ship) when the ship's course took a right angle to the direction of the wind. The method 1. This experiment was carried out in Oshoro maru, a fishing training ship of Hokkaido University, when her speed was 3.5, 6, 9, 12kt, in the Bering Sea. 2. The Luneberg lens reflector (diameter 8 inch) which was connected to the salmon-gill net was selected as the datum point of experiment. In this case, the reflector was allowed to drift equally with the ship by current and wave, but felt no effect from the wind in spite of the movement of the ship. 3. As shown in Fig.1 the observers on the ship measured the distance and bearing of the reflector by radar at observation points 1 & 2, and calculated the side-drifting by those elements and the course and distance of the ship. The result 1. The relation between the wind velocity and side-drifting are expressed by equations (1)〜(4). 2. The relation between the proportional coefficient (K) in the equations (1)〜(4) and the ship's speed (V) is shown K=0.132e^<-0.143V>. 3. By 1, 2, they searched the relation between the side-drifting and the ship's speed and wind velocity, and got the experimental equation as follows U(kt)=0.132e^<-0.143V>W(m/sec). 4. The calculated value in the above-mentioned equation against any combination of wind velocity and ship's speed are indicated in Table 2. 5. The correction angle of the course is indicated in Table 3 when the ship's course took a right angle to the direction of the wind.

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To investigate the ship's drifting due to wind action is an important item from the viewpoint of navigation. However it is very difficult to select the drifting due to wind force from the entire drifting on the sea which reflected the influences of wind, wave, swell, and current. The authors planned to measure the side-drifting due to wind action with parameter V (speed of ship) when the ship's course took a right angle to the wind direction and her speed was 0, 3, 6, 9kt. The method 1. This experiment was carried out in Hokusei maru, a fishing training ship of Hokkaido University, in the Okhotsk sea and the north Pacific Ocean. 2. The corner reflector which was connected to the salmon-gill net was selected as the datum point of experiment. In this case, the reflector was allowed to drift equally with the ship by current and wave, but felt no effect from the wind in spite of the movement of the ship. 3. As shown in Fig.1, the observers on the ship measured the distance and bearing of the reflector by radar at observation points one and two and calculated the side-drifting by those elements and the course and distance of the ship. The result 1. The relation between the wind velocity and drifting are expressed by equation (1)〜(4). 2. The relation between the proportional coefficient (K) in the equations (1)〜(4) and the ship's speed (V) is shown K=0.123e^<-0.137V> 3. By 1, 2, they searched the relation between the drifting and the ship's speed and wind velocity, and got the experimental equation as follows U(kt)=0.123e^<-0.137V>W(m/sec). 4. The calculated value in the above-mentioned equation against any combination of wind velocity and ship's speed are indicated in Table 2. 5. The correction angle of the course is indicated in Table 3 when the ship's course took a right angle to the direction of the wind.

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The effect of winds and waves upon any one ship's speed seems to be different from that upon any other owing to type, size, condition, ability, etc., of a ship ; the author has some interest in the problem of whether the speed reduction of a modern ship has the same tendency as that of a old-type ship or not even if they are the same kind of ship and sail the same sea. In this paper, he has attempted, for example, on a cargo-boat, to analyze the navigational records of the connecting steamer "Hiyama-maru" in Tsugaru Straits. 1. As shown in Fig.1, all data is separated into 7 sections according to the direction of the winds. 2. The relation between the time elapsed after leaving the dock and the slip is shown in Fig. 2. 3. As the speed reductions are changed sccording to the revolutions of the main engine he collected data when the revolutions were from 200 to 220 RPM. 4. The mean speed reductions of the ship, weights of data, are indicated in Table 2 against each section and wind wave grades. 5. Let the speed reduction be expressed by equation (Δ) =aD+bD^2 with parameter D, and a smooth curve is drawn along the points plotted from data, the speed reduction due to wind wave grade is shown by forms (1)〜(7) in each section in Fig. 4. 6. When the values calculated by forms (1)〜(7) are plotted and the smooth curve is drawn along the plotted points, the speed reduction due to the wind direction is obtained as forms (8)〜(11) ; Fig. 5 shown them. 7. Using the wave height deduced from the average values of the grades of wind waves and the meanig of Fig. 4, the relation is expressed by a simple equation as shown in Fig. 6, excepting in the cases of side and favorable winds. 8. The relation between wind wave grade and wind velocity in the strait (1961) is shown in Fig. 8, and the relation between wind velocity and wave height is shown in Fig. 9.

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There are no way aside from increasing of ship's speed or to shorten the anchoring hours in a harbour, for abbreviation term of one round voyage of liner boat. But, there will be some limit point economically in the former idea. The later will be the most effective countermeasure and is one of important subject for rational operation of shipping. Recently, the existing relation of anchoring hours and loading rate, is discontented condition. Namely, the loading rate is a low degree. The high loading efficiency cannot keep every time by ship's excellent loading faculty only, to cite an instances, in equipment and handling system etc. Another conditions should be satisfied. They are cargo amount alongsided to ship's side, number of hired gangs, distribution of gang in and out of ship, weather etc. These factors should be kept in typical condition. The authors have tried the statistic investigation of anchoring hours by New York liner boat at Yokohama, Nagoya and Kobe port. The number of ship for statistics was 185 and the term was about one and half year, from Jan 1962 to May 1963. Results: [table] Remark Hired ratio=Total hours hired gang/Anchoring hours Actual working ratio=Gang-Hours actual worked/Total hired Gang-Hours Waited cargo ratio=Gang-Hours stopped loading due to waiting cargo/Total hired Gang Hours Waited ship ratio=Gang-Hours waited for ship arrival/Total hired Gang-Hours Rain ratio=Gang-Hours stopped loading due to rain/Total hired Gang-Hours As the result of investigation, they understood that the main causes in elongation of anchoring hour are the high ratio due to waiting cargo at Kobe, and stoppage of loading for the sake of rain fall at Yokohama. Another point, the waiting ship ratio at Nagoya should be solved.

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The paper describes a recent addition of a wave generator to the water tank combined with wind tunnel at the Tokyo University of Mercantile Marine. Interest centers on the design, construction and data concerning the wave generator which permits model tests in wind and waves.

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Recently a new Static Leonard Motor with SCR (Silicon Controlled Rectifier) is used for D. C. motor driven directly from A. C. source. The purpose of the present paper is to study a few types of marine use SCR winch. Through the observation of the experience of this new system offers the following advantages in regard to characteristics. (1) As D. C. motor requires no series resistances, its efficiency becomes larger by so much. (2) The controlling characteristics, when hoist and lower notch are taken, are changable easily. (3) The high speed at low torque and low speed at heavy are taken with high efficiency.

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At the Akasi Kaikyo and approaches, disasters are happend by small crafts. About 45% of small crafts which made the disasters are stranded near Hira Iso, Yamada Iso, Semento Iso. Collisions and other disasters are occured all over the strait. Many small crafts are sailing under the tidal current, the typical route of them are shown in Fig. 8. Many eastbound crafts adopt the route which cross the strait, many westbound crafts adopt the route along the coast of Akasi.

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Authors devised a theoretical formula to explain the method of "Williamson turn" as described in "Naval Shiphandling" published by U.S. Navy. This formula based on simple approximations and steering indices T and K. We examined the reliability of the formula by the ship experiment of G.T. 150t-training ship to obtain satisfactory result. Then we may know theoretically the most suitable chance of reversing the helm in the "Williamson turn".

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The characteristics of satellite navigation system are discussed on comparing with the usual astronomical navigation by means of the natural celestial bodies. Necessary conditions are also considered which the satellite navigation system should satisfy for commercial navigation. Taking the conditions into account two systems of satellite navigation are described: the zero radial velocity method and equal distance method.

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