A number of marine disasters of small vessels have been occurring along the coast of the Japan Sea, and in those cases are found most often drifting vessels due to engine troubles or drifts, such as lumber, life-jackts, life-boats, etc. coming from sunken vessels in distress due to heavy weather. In order to obtain data, such as the inference of the oosition in distress, etc. from the drifting conditions and materials, experiment was conducted through drifing various kinds of materials from a patrol-ship off the Wakasa Bay for five hours (1010-1510), Sept.4, 1962, with a considerable result, and it shall be described herein.

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Observation of the distance, bearing, or altitude of an object gives us one of its primary position lines. When two objects are given, the difference or sum of their distances, bearings, or altitudes makes a certain type of position line. And if the object is moving with constant velocity, the time variation of distance, bearing, or altitude makes a position line. The author studied the characteristics of these position lines on the surface of the earth.

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Luneberg lens reflector is far superior to the corner reflector for wide angle e.g. 140 degrees and has a radar cross section approximately eight times that of a circular corner reflector of the same radius. Some typical data at x band are presented for 5-inch & 10-inch diameter Luneberg lens reflectors manufactured now. The measured values of radar cross section are within 1.1dB below the theoretical. A lens which act as a true ommi-directional radar reflector called as Eaton-Lippmann lens reflector is also manufactured and some typical data at x band are presented for 5-inch diameter lens. The measured values of radar cross section are approximately 5.9dB below the theoretical and the variation of directivity is within ±0.8dB. Both Lunebery lens reflector and Eaton-Lippmann lens reflector are now in production.

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MK.Es is a small gyro compass which was developed by Tokyo Keiki Seizosho Co. in 1961. It has two types, one of them which is called Mod.1, has been developed for the installation of 85-tons-class fishing boats, the other which is called Mod.2, has been developed for the installation of 250-tons-class fishing boats. Angular momentum of the gyro is comparatively large (0.67×10^8c.g.s.), but its binnacle which 450mm high, and 300mm diameter is very small. As the supporting system of the Es gyro is completely different from the other existing systems, therefore the binnacle of MK.Es is about 1/3 in volume as compared with the binnacle containing the same size gyro with the structure of the existing Sperry-type gyro compass such as MK.E_N.

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In these days, a great deal of new radio navigation systems are being developed and though utilization of Redio Direction Finder System which takes advantage of straight propagation of radio wave only is decreasing, it is still useful system especially on coasting vessels and fishing boats in our country, moreover it sometimes carries out some peculiar duties like in salvage. This Radio Direction Finder System accompanies various errors and though now most of them have been solved, it is necessary to understand exactly of these errors to get a high accurate ship's position. In this paper, we tried to solve the error caused by ship's heelings which has not been solved yet. At first the heelings are divided into pitching and rolling and of each cases the curve of directional error caused by ship's heeling on Direction Finer which has loop antenna is cleared. It is similar to the quadrantal error. In these cases, the errors are negligible when the radio wave comes from athwart ship or fore and aft diraection and they come to maximum value when radio wave comes from the middle of these directions. Though the maximum value is negligible when the heeling angle is small, it comes to 4 to 8 degrees when the heeling angle becomes 30 to 40 degrees and then it is not negligible. In the next case which both pitching and rolling occur together, the error curve is quite complicated and its value becomes greater than each cases showed above, moreover in this case it also became clear that the error curve varies according to the direction of heeling.

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To analyze the effect of winds and waves upon a ship's speed is a very important problem to determine the economical sailing course. But each ship being different from any other in type, size, condition, ability, etc., it is not possible to formulate any universal rules. In this paper, the author has attempted, for an example, to analyze navigational records of fishing training ship "Hokusei-maru" of Hokkaido University. As shown in Fig.1, all data are separated into 7 sections by the directions of the winds. The calculation of speed reduction is by the difference between the standard speed 9.34kt and the log speed converted in the speed when the revolution of the main engine and the angle of blade are standardized, under each condition ; the standard speed is that shown by the sal log when the standard rotation is 300 RPM and the angle of blade is 13.8 degree, and the influences of wind, wave and swell are nil. In Table 1, n… shows the number of data, △… shows the mean speed reduction ; the items of data are 1734 in all. As the speed reduction (△)=aB+bB^2, if a smooth curve is drawn along the points plotted from data, the speed reduction due to wind force is shown by forms (1)〜(7) in each section, as shown in Fig.2. The calculated values by forms (1)〜(7) are plotted and if the smooth curve between the speed reduction and wind direction is drawn, that curve approaches closely to the curve of 5th degree shown by forms (8)〜(14), as shown in Fig.3. In order to get the relation between wave height and speed reduction, the following method was taken for deducing wave height from wind scale, that is, the average value was taken of the grades of wind waves against each wind grade in the navigational records, and the wind grade was replaced by the average value of grades of wind wave scale. The intermediate value between the grades of the scale is shown by the proportional difference. The relation between wind scale and wave height in this observation is expressed by the equation H=0.0697B^<2・1>. Using the relation and relation in Fig.2, the relationship between wave height and the speed reduction is expressed by a simple equation.

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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 whether or not the speed reduction of a ship in ocean has a same tendency as that in a specific sea. In this paper, he has attempted, for an example of it in the specific sea, to analyze on the navigational records of the connecting steamer "Seikan-maru" (cargo-boat) in Tsugaru Straits. 1, As shown in Fig.1, all data are separated into 7 sections according to the direction of the winds. 2. The relation between the elapsed after leaving the dock and the slip is shown in Fig.2. 3. As the revolutions of the main engine are changed according to the circumstances he converted those speed reductions into the reductions when they are fixed in 190 RPM. 4. The mean speed reductions of the ship, number of data, weights of data, are shown in Table 1 against each section and wind wave grades. 5. Let the speed reduction be expressed by equation (△)=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.3. 6. Using the wave height deduced from the average values of the grades of wind waves and the meaning of Fig.3, the relation between wave height and speed reduction is expressed by a simple equation as shown in Fig.4, excepting the cases of favorable and side wind. 7. The relation between wind wave grade and wind velocity in the strait (1960) is shown in Fig.6, and the relation between wind velocity and wave height is shown in Fig.7. 8. The mean fetches in the strait corresponding to each direction of wind are shown in Fig.8.

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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 whether or not the speed reduction of a ship in ocean has a same tendency as that in a specific sea. In this paper, he has attempted, for an example of it in the specific sea, to analyze the navigatonal records of the connecting steamer "Yotei-maru" (passenger boat) in Tsugaru Straits. 1. As shown in Fig.1, all data are separated into 7 sections according to the direction of the winds. 2. The relation between the elapsed after leaving the dock and the slip is shown in Fig.2. 3. As the revolutions of the main engine are changed according to the circumstances he converted those speed reductions into the reductions when they are fixed in 190 RPM. 4. The mean speed reductions of the ship, weights of data, are shown in Table 1 against each section and wind wave grades. 5. Let the speed reduction be expressed by equation (△)=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.3. 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.4 shown them. 7. The relation between wind wave grade and wind velocity in the strait (1962) is shown in Fig.6, and the relation between wind velocity and wave height is shown in Fig.7. 8. The mean fetches in the strait corresponding to each direction of wind are shown in Fig.8, and calculated wave height by S-M-B method are shown in Fig.9.

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The equation of steering motions of ships can be described by a differential equation of the 1st order as follows: [numerical formula] where T is a constant which represents the quick responsibility of ships, and K is a constant which represents the turning quality. The performance of the turning motion of ships is decided by these manoeuverability index T and K. These index can be obtained from a Z manoeuvering test or a turning test of ships. On the other hand, turning motion of ships is represented on the Phase Plane which has the coordinates of angular velocity (on the ordinate) and angular position (on the abscissa) of ships. To minimulize steering time, the principles of nonlinear Optimal Control system can be applied to the steering motion of ships. The optimum switching point, when ships are steered from port to starboard or from starboard to port, is decided on the Phase Plane by application of the nonlinear Optimal Control theory.

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To investigate the towing power for movement the ship broadside into her berth when wind is blowing off the pier, wind-tunnel with water tank experiment were carried out. The results are summarized as follows : (1) the coefficent of wind force is increased with the aspect ratio of the lateral projected area of the above-water part of the ship. (2) the effect of bottom clearance on the drag force caused by under-water part to move her broadside is very significant.

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ブイ係留中のふれまわり運動の振幅は,極端に錨鎖を絞つた場合を除けば,係留錨鎖が長いほど,また船尾側にトリムをつけるほど大きくなる。しかしこの際錨鎖に加わる張力の最大値(衝撃的な性質のもの)は,かならずしも錨鎖長に比例して増すとはかぎらない。第1報では軽荷状態の模型船についてこのことを確かめたのであつたが,別の載貨状態に対しても同じことが言いうるかどうか,その後の実験結果を以下に報告する。船尾トリムよりも船首トリムの方が有利であることは,ブイ係留についても言いうるので,煩雑をさけるため等吃水の場合に限定することにし,載貨状態のみ半載,3/4,満載の3種類に変えたときの効果を比較する。なお前報の軽荷状態の成績ともあわせ比較した。模型船,その係留要領および測定装置は前回と同じである。なお今回は風速を約30m/sに限定した。

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Measurements on the drifting and the direction of the drifting of ships due to wind action, while their engines were stopping, were made by means of radar watching directed to a corner reflector on a buoy connected to the salmon gill net, which was hardly affected by the wind action. From 30 observations during the cruises of the "Oshoro Maru" II every summer 1957 to 1959, and 47 observations during the cruise of the "Oshoro Maru" III in the summer of 1963, in Aleutian Waters and the Bering Sea, the following results were obtained ; 1) In the "Oshoro Maru" II, the ship became to receive the wind a little ahead the beam, while in the "Oshoro Maru" III, the ship became to receive the wind a little abaft the beam. Both ships were drifting leeward to a little ahead the beam, not in the same direction as the wind. 2) On the relationship between the drifting velocity of the ships and the wind velocity, the following experimental equation was obtained: "Oshoro Maru" II when: S/S_ω=1.66 v=0.119W then: v=0.092√<S/S_ω>W "Oshoro Maru" III when: S/S_ω=1.90 v=0.136W then: v=0.098√<S/S_ω>W when: S: Longitudinal projected area of ship above water-line (m^2) S_ω : Longitudinal projected area of ship above water-line (m^2) v: Dirfting velocity (kt) W: Wind velocity (m/sec)

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The twin quadrilateral spanker consisting of two sails and two booms as shown in Photo.1, set on the afterside of the aftermast is used in saury stick-held dip net fishing and mackerel angling for the purpose of keeping the bow toward the wind direction while drifting. For the study of the aerodynamic characteristics of the spanker, the writer performed wind tunnel experiments using the sail models with parameter θ, open angle between twin booms, indicated in Table 1. Their coefficients to various angles of attack α about each model expressed by equations (1) are obtained as shown in Figs.3-10, and the distinctive features of the spanker were made clear. Making use of the results in experiments, some considerations about the advantageous quality of the spanker for the above-mentioned purpose are presented in the latter part of this paper.

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Concerning the studies of ship's motions in a seaway, a wave measuring instrument has been designed by the author for the studies of ship's motions among ocean waves taking the wave to represent the input forces to the dynamical system of the motions. In this instrument, for ocean waves in deep water zone, a radio telemetering system is devised for use in recording and measuring ocean waves using a bamboo stick wave pole. In respect of the measurement of wave heights on an actual sea surface, measuring and recording the vertical distance from a certain point to the sea surface continuously, wave heights and periods and other wave properties should result from analysis of this record in statistical meaning. As to the method of this scheme of measurement, a freely floating buoy has been used, such as the Froude wave pole or WHOI wave pole. The measuring and telemetering apparatuses are attached to this pole. In this paper, general discriptions of a wave pole and of a measuring and telemetering system of ocean waves in deep water zone are presented.

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The authors wish to show, in this report, the relation between the yaw-angle and the rudder angle during towing the net, which is thought to be one of the problems of basic importance specific to the fishing-boat, through the comparison of the records collected during towing with those during the ordinal navigation free from towing any net, although we know the occurrence of the phenomena probably with somewhat similar nature observable in the ships other than fishing-boat, for example, tug boat, etc. The details of towing the net vary with the fishing methods ; but, here, the authors take up the case of trawling, because the net is towed along straight line, consequently trawling is thought to be the simplest case and is easiest to analyze. While special attention should be paid to the fact that trawl-net is supported by "the towing block" on her stern at starboard side. So far as the present study has concerned, the following tendencies are found out: 1) In order to keep the ship with less stability of her head on her appointed course, towing makes the ship require the rudder angle larger than in the case towing no net. 2) The rudder angle during towing changes nearly in proportional to the yaw-angle with less deviation than in the case towing no net. 3) Undamped oscillation can be found during towing in either yaw-angle or rudder angle.

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The paper describes on a method of the investigation into the actual condition for routing traffic in the Akashi Strait that the excution are under way for the Cross Channel Bridge Scheme. And we are recording the flow of shipping and the fishing activities in the strait by means of the Radar Photogragh and the Obsrevers Sketch.

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In winter season, annually, many human lives and means have lost by sea accident of two boat trawler. As the preliminary analysis to its cause the writer investigated their field condition at fishing ground by reseach ing fishing boats and their crew at the Nagasaki Fish Market in August 1963. As the results, it was found there were some difference of maneuvering between large vessel and small boat, and many characters of two boat trawler were studied as following each parts. 1. stability 2. engine control 3. position plotting 4. design 5. skipping in ugly weather 6. human organization, fishing commander system and others

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Authors have studied about the bridge consol of the automated ship, and designed a suitable consol for the T.S. "SHIOJI-MARU" which was already manufactured and equipped on her. They report what works are to be done by this consol and then what instruments are to be fitted on it.

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The bridge central control system of the ship is the control system that the operations of maneuver and watch on the navigation, communication and power plant of the ship are performed concentrically by one or two operator in the bridge (steering room). Authors have made the instrumantation of the power plant of the T.S "Shioji-maru" to meet purpose of the brige central control system, and made sea trial of the system.

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