Many small boats have run aground at the coast of Japan. The tonnage of these ships is allmost less than 500 tons. Thay have only a steering compass in the wheel house, by The Ship's Safty Law. This compass can not take two or three landmark's directons at the same time to fix a ship's position. It is important to establish a exact compass at the flying bridge of the ship.

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The authors reported formerly that the correlation coefficient between mixing ratio of quay and barge cargo and loading rate is in positive value at Yokohama Harbour. In consequenence, it should be increased the mixing ratio for leveling up the loading rate. Recently, they tried the statistic investigation on the relation between the mixing ratio and loading rate at Kobe, Nagoya and Moji Harbour. As a result, it was cleared up that the correlation coefficient is in negative value at Kobe against to the sign at Yokohama. Namely, the loading rate decrease with increase the mixing ratio. This conclusion is against to the rationalism of ship's loadig on a wharf. But it became clear that the exact causes are based on the unsuitable management of terminal operation, especially on the apron of wharf. It should be utilized of the working area on apron with shed spaces effectively.

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When goods are loaded on a ship, it should be certified that the draft, the stability, the distribution of shearing force and bending moment are approved for the safety of ships. This computer was produced by way of trial in order that they might be calculated rapidly and exactly and this object was attained nearly.

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To research the traffic flow, amount and etc. in the Kaburako Suido, I have made an testing survey for three days from Feb 7th to 9th 1968. In this paper I reported the cine photographic method with synchronized pair-16mm cine camera. Ship's flow, amount and exceeding speed were carried out very effectually and economically by alone observer.

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We have already reported the actual condition of the ship traffic in the Hayatomo Strait. The behaviour of the wooden boats under 300 GT (the so called kihansen in Japanese) can not be treated lightly from the standpoint of captains or officers of the larger ships, so we examined in detail the actual traffic conditions of these wooden boats in the Hayatomo Strait on the basis of the same data. The results obtained are summarized as follows: (1) The traffic volume of the wooden boats per hour in the nighttime is about 30% of that in the daytime, and the traffic volume of the wooden boats at the adverse tidal current is less than 30% of that at the favorable tidal current. (2) Especially in the case of sailing to the westward, the habitual course of these wooden boats differs remarkably from that of the ships of larger size. (3) The ratio of these wooden boats sailing on the course close to Mojizaki is smaller in the nighttime than in the daytime, and the rule that any boat or ship should adopt its course in the right-hand part of the recommended route is followed more faithfully in the nighttime than in the daytime. (4) The ratio of these wooden boats moving in face at the distance less than 60 meters from any other ships or boats in the narrowest part of the Hayatomo Strait is about 10% both with the large ships and the small boats at the adverse tidal current, and the ratio is about 15% with the small boats but zero with the large ships at the favorable tidal current.

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The Kanmon Strait is located on one of the most important routes in Japan. The results of a traffic survey of its eastern half, the Hayatomo Strait, had been reported ; but there remained that in the western half, the Oseto. This needed the necessity of conducting a similar survey for the remaining half, to understand clearly the traffic conditions of the Kanmon Strait. The first four day radar survey with visual observation was conducted from Aug.21 to 25 of 1967 for Area B, and the second one from Aug.30 to Sept.3 for Area A. The results obtained are summarized as follows: 1. More than 800 vessels passed through the strait a day. 2. About a half of them was those smaller than 100 G.T. 3. About three quarters of them passed in the daytime and the rest at night. 4. The strong tidal current did not cause any remarkable decrease in the passing of the vessels. 5. One of the most admonitory findings was the passing of small boats across the lawful course. This suggested much risk of inducing collision. Namely, the vessels over 3, 000 G.T. passed along the fairway regardless of the relative direction and speed of the tidal current. In contrast with this, both of the easting and westing courses of the smaller boats than 100 G.T. converged into along the northern periphery in the Oseto, but diverged over the western waters adjacent to it.

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The authors investigated by radar instruments trajectries and speeds of ships passing through the narrow channel "Kurushima Kaikyo", which is one of the most difficult channels for safe navigation in Japan, because there are rapid currents and many altering points. Many radar photographes of ships underway were taken at intervals of one minute with a 35mm motor drive-camera for ten days. After choosing samples at random, 468 ships were analyized. These procedures are very effective when considering the route regulation for safe navigation at a narrow channel.

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The authors reported formerly on the preliminary research under the average traffic condition, in Summer, 1965. In succession, we have made the second observation for 25 total number of days from 28th Nov. to 30th Dec., 1966, under the crowded traffic condition, using a milimeter wave radar. This paper describes on the results of study, concerning about general and abnormal features of ship's track and flow, navigable rooms, amounts of traffic, time intervals and speeds of passing ships and traffic capacity in this water area.

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There are some pulse-like disturbances in solving the optimum ship routing. Then, the writer showed the algorithm to get a solution in such situations using the art of dynamic programming.

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The authors have already obtained the theoretical wave chart of North Pacific Ocean in winter, using Mollie Darbyshire & L. Draper's table with the data of the Weather Maps. But the analysis was to be risen by the superior wind. In this paper, the wave height, the wind velocity and the wave period of all directions are shown and compared them with the meteorological reports by ships.

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To give exact effects to optimum or economical routing, one of the essential requirements is the knowledge about the ship's response to the wave-fields. On that account, the authers tried to analize the reduction of ship's speed by the ocean wave by means of statistical method. Five ships of nearly similar type & power were abopted as the typical model of ocean-going cargo boats, one of which was with twin-screw and others were single-screw. Data exracted from their Log-Book were divided into 3 sections according to the relative direction of the wave. In each section, speed reduction is estmated as the function of the wave-height as shown in Table 5. As the result of comparative analysis, the performance of a twin-screw ship has prove inferior to single-screw ships as to speed reduction this type.

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The contour of constant area of error boundary is equal to contour of the probability density of the fix. On the other hand, radial error constructed by radius of max error is the easiest way in constructing and has more ever practical value. It is to say that the radial error is not theoretically good enough. We study that the error boundary of Running Fix by using max error parallelogram and max radial errors. We consider that the fix is obtained by two position lines from the same object by Running Fix method is equal to the fix by simultaneous observation by cross bearing from S_1 and S_2 which is advanced object S_1 existing in the error boundary of estimated position when ship's running course or distance is wrong. We constructed contours of constant probability density for Running Fix, and also, contours of radial error. So, we made a comparative study of the both contours. That is, 1. The best way of determining the fix by Running Fix method is to observe the bearing of the object at the close of ship's head line in the first observation, and to observe the bearing of the same object at the points to see it within 20°abaft the beam at the second observation. 2. The figure of contours of radial error is different from the figure of contours of constant probability density at the area that angle of cut is obtused. This fact is point out by the roughness of radial error, therefore, figures of these contours have become to contrary way. By the above contours, we think tha the error of Running Fix is made to clear.

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I determined the height above the datum line by deducting a predicted height of a monthly mean sea level above Datum level from an observed height of a monthly mean sea level above the datum line. I obtained a predicted tidal curve by adding a predicted height of tide to the height above the datum line. Comparing mareograms with predicted tidal curves, I determine a rough expression, H(cm)=1.9(1010mb-Pmb), by which we could forecast the meteorological tide-the maximum sea level departure from normal-at Toba Bay.

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In summer, SS3 rate of Loran C is simultaneously measured by visual receivers of three types at two points which distance is about 150 miles in East China Sea. Additionally, the other data obtained at various points in spring and autumn are introduced for reference. The outlined features of both the coverage of ground and sky waves (contains the diurnal changes of reflecting height) is defined. The deviations from the computed value of sky wave (fig.5) are constant, as a result, the ionospheric heights of day and night will be adjusted. The deviations of integer multiply of 10 microseconds are commonly seemed to be due to unavoidable characters of such visual receiver. The author, however, supposes that the deviation is caused by the correlation of geographical position, the characteristics of propagation and the solar time. Because the 10 microseconds deviation of upper side of standard value are obtains in Tanegashima (2 position), (fig.2, 3), on the contrary, that of Mejima and Yamakawa are in lower side. When the transmitting station is in the eastside of receiving point the deviation might be in lower side, on the other hand, in the westside is in upper side. The time of sunrise is completely coincides with the variation of the height of ionosphere in daytime, but the height of nighttime is slowly changeable. The average deviation of X chain over land at Mejima is +2.3 microseconds.

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The probability of the maritime distress of world tankers, calculated form the number of ships, in the Lloyd's Weekly Casualty Report, and the Lloyd's Register of Shipping Statistical Table, shows following particulars relating with the size (in gross tonnage) of the Ships. (1) The bigger tanker has the higher probability. (2) The trend of probability of continuous two periods look like each other, when the number of distress ship amount over about 500. (3) The trend of probability of heavy distress resembles closely the probability of all distress.

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Negligence on board, is generally caused by carelessness. Engish explained: Die sorgfalt als unterlassung gefahlicher handlungen, Die sorgfalt als ausseres handeln in gefahrsituation. Die sorgfalt als erfullung der rechtbeachtungspflicht: I want to fix the meanings & contents of negligence on board by the classification done by him.

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In small vessels there are many kinds of autopilots, though autopilots are recently popular for their facility and good controllability. Considering these from the construction of automatic control system, we can classify them into three classes as follows: -One is corresponding to "two unit" (we say C2) for large vessels, another is to "single unit" (C1), and the third is to a new system that has a branch to feedback at receiver of telemotor (C0). In this paper we analyzed controllability in three different types of autopilots, and investigated it by analogue computer. It was ascertained that C2 type showed the best controllability and C0 was better than C1 type.

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The definition of "Miscellaneous Vessels" in Japan Port Regulations Law should be furthermore explained by the practical sense of seamen. But this sense has not been so clear and popular as a practical sense worth mentioning, in this case. So, this papar tried hard to clarify the practical sense of seamen and the necessary conditions for a miscellaneous vessel with reference to cases of judgements by Marine Accident Inquiry Agency, but some remains to make them clear up. Hereupon, it is fully realized that the defects of the definition and the institution of miscellaneous vessls has been still remained.

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For the purpose of finding out whether the cognition and the judgement of a miscellaneous vessel has been clarifying or not, a investigation on small power-driven vessels was practised in Nagoya-Ko and following results were obtained. 1. They only use the definition in Law and do not use the practical sense of seamen as a standard for above mentioned cognition and judgement, in practical affairs, 2. A tendency that it is safe to give their way to the other, irrespective of whether they are aware of themselves as miscellaneous vessels or not, is found. 3. About 40% or more of all cognitions of misecllaneous vessels or vessels other than miscellaneous vessels are nor proper. 4. Large probability of vessel's collisions due to the difference in the opearations mentioned at the main title of this paper, has always been exsting in harbor. 5. Because of dlfficulty in understanding a miscellaneous vessel in practical affairs, it is expected that the Law makes miscellaneous vessels display the specified signals and makes all vessels sure in being aware of a miscellaneous vessel, if the institution of miscellaneous vessels is maintained further.

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Recently the technique of the optimum control or the adaptive control has been brought into autopilot, and intention to judge the ability of the system quantitatively by the performance index is generally favoured. In this paper, the authors would like to treat the system on the time domain, and introduce the control area method to measure the ability of the system. The authors concluded the following performance index to be suitable for autopilot, namely: [numerical formula] where <θ>^^^(t : course error δ(t): rudder angle

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In previous paper the authors considered the optimum adjustment of autopilot which contains proportional control only, and proposed that the following performance index is the most suitable criterion for the system, namely: [numerical formula] In this paper above function will be confirm to be suitable for the system to which the rate control is added. And an aim for the tecnique of the optimum adiustment of the two-valiable system was established.

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漁船の主機関使用の特徴は,漁撈作業中その過程に応じて頻繁に発停・変速することである。この特徴を示す典型的な実例としてマグロ延縄揚縄作業中の主機関運転状況を調べ次の結果を得た。1.マグロ延縄の揚縄作業中には毎時平均前進16.5回・後進1.8回・停止17.6回,すなわち1.7分に1回の割合で変速を行なう(第1図)。2.漁獲が多くなるに従つて,同じ長さの延縄を揚げる間に行なわれる前進・停止・後進の回数はいずれも増加し,1回の前進極微速の時間は短くなる(第2図・第3図)。3.風が強くなつても(ビューフオート階級2〜5の範囲では)主機関の発停回数は変わらないが,1回の前進極微速の継続時間は長く,前進後の停止の継続時間は短くなる(第4図・第5図)。

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マグロ延縄揚縄作業中は主機関を頻繁に発停させる。一連の運転動作の中の各動作は,その前の動作の影響をうけ,後の運転動作に影響を及ぼす。先ず各運転動作が無作為な順序に行なわれるときに,ある種類(継続時間の差異も含める)の運転動作からk動作後(k=1,2,…n)に行なわれる各種類の運転動作の期待回数とそれに対応する実測回数を比較し,次に停止と前進(または後進)が交互に繰り返されることを前提にしたこのような期待回数とを比較することによつて,次の傾向が明らかになつた。1.マグロ延縄揚縄作業中の主機関運転操作の基本型は前進-停止の繰り返しの間に少数の後進-停止が入つたものである。2.kがあまり大きくないとき,期待回数よりやや多く行なわれる傾向がある組み合わせは,長い前進*短い停止,短い前進*長い停止,後進*短い前進・短い停止。3.期待回数よりやや少ない傾向がある組み合わせは,短い前進*短い停止,長い停止*後進である。

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