In previous papers the author explained obviously that weather adjustment by backlash or its equivalent loop in present autopilot would cause self excited oscilation. As the loss of ship's route by this oscilation is great and harmful, weather adjustment by low pass filter or dead band has been proposed for the purpose of excluding this oscilation. The author designed this time the unit system weather adjustment by combination of integral and differential elements, and compared the unit system with above mentioned low pass filter and dead band by analogue simulation. As the result of investigations, the author confiremed as follows: -The unit system developped by the author not only had a function of protecting the steering engine from overwork, but excluded self excited oscilation. And so it possessed the optimum controlability as weather adjustment.

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The utility of the Loran C system by using a manual visual receiver-indicator seems to be increasing now in the world, most of the data on this system, however, are on the coverage area and accuracy by using the full automatic device. We researched and investigated as to the accuracy by manual device at a fixed observation station and it is found that the reading of the time difference often changes at every 10 microseconds in spite of severe measurement and that it will be unavailable to read out without this discrepancy by these conventional receiver-indicators.

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The author measured the time diffrence of Loran -A in the southern waters of Kyushu for several years, and obtained following results. 1) The constant deviations of the time difference was found in this water, but, they were proportional to the distances from master and slave station. From the result, it concluded that the velocity of Loran radio wave varies faster about 12.2km/sec comparing standard value (299, 708km/sec, for use Loran table) in Fig.3. The pattern of the deviation coincides with the Loran hyperbola. 2) According to many data it seems to be ascertainable that the velocity of 2Mc/s is more affected by the conductivity of sea water than by the refractivity of atmoshere. 3) The deviations in this waters on which the mountain (for example, 500 meters and 700 meters in height) cross the water vary remarkably, however, these values reset normaly at 8 nautical miles from the coast. The author considered that this phenomenon above mentioned are due to the shadow effect of mountain and the recovery effect.

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The altitude-azimuth method has been used worldwisely since the line of position was discovered by Sumner. However, the method has some defects that a dead reckoning position, a straight line of position against a position circle and so on are used. The writer, then, devised a method of position-fixing by the observations of celestial bodies by the aid of analytical geometry including running fix, altitude corrections and ephemeris problems for electronic digital computer on board. According to the method, the position with high precision and the angle of intersection of position circles can be obtained with only U.T., the names of celestial bodies and the observed altitudes.

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It is desirable to get nautical almanac data from a digital computer through approximate calculation, when we fix ship's position with the computer by astronomical navigation. Fourrier series interpolation seems to be most suitable for the purpose, because right ascention and declination of a celestial body are nearly periodical functions. The author programmed formulas and calculated them with HITAC 5020E. Calculation time: About 0.005sec for R.A. (or E_*) and dec. of every fixed star, when 7 coeff. are used for each one of the factors. About 0.02sec for R.A. (or E_*), dec. and S.D. of the sun, 25 coeff. for every factor. Max. error: ±1.0sec, ±0'.1; ±1.2sec, ±0.'12, and ±1".0 respectively, where the coefficients are determined from Japanese nautical almanac (1967) data. If ephemeris data are used, maximum error will be reduced to a tenth of the above value. Recommendation: To put calculation formulas and accurate coefficients into print on a nautical almanac.

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The errors of ship's position fixed by the system using the altitude and azimuth measurement of the artificial satellite are analysed. The position error of this system is best when the satellite is on the equator. At subsatellite point, the position error is determined by the directional sensitivity of the aerial and the vertical sensitivity of the platform, and the north reference sensitivity has nothing to do with it. The larger the difference of longitude is, the larger the error is. Therefore, when several synchronous satellites are arranged at suitable intervals, then the worst areas will be removed.

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The ship-born noise under water is supposed to range to a considerably high frequency judging from the noises detected under operating of the echo-sounders of various frequencies. Studies on the ship-born noise have been reported by Hashimoto, Maniwa, Nishimura, Shibata and Kuyama (1)〜(5), and experiments on flow noise by E.J. Skudrzyk (6). In the present work, the variance of the ship-born noise of our training ship the Nagasaki-maru at various velocities has been recorded and analyzed by the Sonagraph in order to investigate mainly the aspect of the ship-born noise in relation to the noise caught under running of the echo-sounder. The results obtained aer reported here.

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In thse observations the direction and the velocity of ships drifting by wind action with engines at a stop were calculated by taking the bearings of the big flag at the end of tuna long lineby means of the gyrocompass of the ship and by taking its elevation (vertical angle) by the sextant and so measuring the distance. The following are the results according to the drifting observations made at 151 spots by the Taisei-maru while practising in tuna fishing in the Pacific Ocean of 01°〜15°N., 97°〜100°W. from March to May and from October to November in 1965. (1) As for the Taisei-maru the velocity of drifting is approximately proportional to that of the wind. (2) The ship is apt to drift catching the wind 1〜2 points before the beam. (3) The central direction of drifting is 15°〜20° ahead from the direction in which the wind blows away. The stronger the wind blows, the more remarkable this tendency becomes. If the velocity of the wind is more than 7.5〜10.0m/sec, the ship does not drift astern any more. (4) The best way of watching the tuna long line is thus to sail on setting it to the weather side catching the wind about 2 points from the bow on the lee board in case of drifting and then to drift with the bow turned toward the direction where the fishing implement is stretched. In this way we can easily find the long line after we have drifted beyond its end and even lost sight of it because we must necessarily meet with the implement if we sail into the wind from there.

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There are many problems awaiting solution to keep health of crew in the present pelagic fishing boats. This paper summarizes the results investigated in the practices of oceanographic observations, exploratory tuna long-line fishings, and trawlings in the waters of Bering Sea and tropics during the extensive cruises, 1963-65, on board the fishery training ship belonging to the Shimonoseki University of Fisheries. From the data obrained we conclude as follows: -1. Peculiarities of patients varied with the term of navigation, cruising areas, nature of operation, conveniences in the ship, the number of embarking persons, condition of health after embarkment, etc. 2. Three main diseases in the rate of outbreak were gastro-intestinal, respiratorical, and surgical. 3. The rate of crew's gastro-intestinal diseases was higher than students' and of student's respiratorical diseases was higher in tropics than in cold waters, and student's surgical diseases increased as the navigation was prolonged, compareing with crew's.

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In the Sea of Okhotsk, ice formation begins at it's northwestern corner ; near the Shantalski islands in the latter of October. The ice area rapidly extends Southeastwards along the East coast of Sakhalin facilitated by NW'ly winds and low saline water. In this paper, I attempted to catch the daily ice limits of the Sea of Okhotsk using the meteorological satellite and radio sonde data at 17 stations for two years. 5 day-mean surface water temperature, 10 day-mean 850mb temperature and monthly-mean 500mb temperature were also observed.

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The distribution of the ships anchoring in Osaka Bay is investigated from the harbor radar photographs when a typhoon approaches. The distance between the closest two ships is measured and the mean is calculated. It is also investigated that how many ships can anchor in Osaka Bay. If we consider that the anchorage belong to one ship is a circle having a diameter of 1650m which is nearly equal to the mean distance of the two ships, it is said that only about 180 ships can anchor in Osaka Bay, and it is concluded that the anchorage area in Osaka Bay must be insufficient in near future when a typhoon approaches.

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Near the entrance of Ise Bay, a local strog wind frequently prevails when the winter monsoon under blowing. In this report I investigated the characteristic of the strong wind using the surface data at 15 stations for 5 years and 950mb data with helicopter. The rader data at Nagoya Local Meteorological Observatory, APT pictures from meteorological satellite, street clouds and surface water temparature were researched in connection with the strong wind on the surface too.

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The following plan is made clear-building of a special route for a Sugashima Suido. The reason of the above is as follows: -The 16 meters depth of Irako Suido is no more useful for the manmoth tanker. And the sailing ship is increasing in number. The unsolved problems are many. The planning route has many sunken rocks here and there, has two windings and it is narrow. Moreover the sea is the only good fishing grounds here in Ise Bay and there are many fishing boats there. So, we hereby report the following, from the standpoint of a navigator, based on the actual examination by an airplane and a training ship.

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The Hayatomo Strait is located on one of the most important maritime routes in Japan. The trend of increase in the vessels passing its narrow and curved fairway with strong tide made us feeling the necessity of the present survey. Three series of 24 hour radar photographic and visual observations were conducted on Aug.17, 21, and 26, 1966, after a preliminary observation on Aug.14. And the results obtained are summarized as follows: 1. As many as 900 vessels passed through the strait a day. 2. About 60% of them were those smaller than 100 G.T. 3. About 70% of them passed in the daytime and the rest at night, the rush hour being from 06.00 to 10.00. 4. The strong tidal current did not cause any remarkable decrease in passing of the vessels. 5. The course of passing varied with the size of vessels: Those over 1, 000 G.T. were inclined to pass along the fairway regardless of the relative direction and the speed of the tidal current. Most of the boats of not larger than 100 G.T. were inclined to take the course very close to the southern coast especially when they pass against the current, but to take diverse courses over, the fairway when they pass follwing the current.

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The tuna long line fishing in business is one of the most important fishing in Japan. But the catch of fishing decreases recently, so clippers are obliged to go out deep sea and to stay at sea for long time. The clippers have to become larger and larger and have large power engine for sake of compensating the loss of economy. There should be an opposite properties between fishing abilities and navigational requiements. We can not ease to take off this custom on the charactaristics of fishing. Author collected the data of tuna long line fishing boats more than 120 in number and compared the boats which were built after 1963 with the ones were built before 1962, and tried to solve in this problem on view point of both economical and fishing ability.

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There is no method and equipment to measure the speed of small boat accurately. Then we trially made a measuring equipment which use L type Pitot tube and some experimented with this equipment at the several conditions. The results of this experiment were nearly equal to the results obtained with the measured speed by a float.

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We presented on our report I that it is convenient to obtain and use the dimensionless function table concerned with the tension and configuration of towing rope. To acertain these results we made the following experiment: the towing end-free rope. In this experiment it becomes clear that masured value becomes nearly equal to the calculated value with the large specific weight wire rope, but the measured value is not coinside with the calculated value with the small specific weight rope as the cremona.

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Recently, a special feature of the type of many trawlers turn into stern-trawler which supports towing tension of the trawl-net at the end of her stern. In the present paper, the author has analysed the motion of stern-trawler in steered condition under towing a net, especially about the effect of towing tension and propeller slip ratio on the manoeuvrability of ships. The analysis showed the following facts: By the effect of towing tension, directional stability of the trawler under towing a net increases and not only decrement of the yawing becomes rapid but yawing period changes in short.

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This paper deals with the results of experiments toward the sea anchor of parachute type, which was improved from parachute. During drifting with a sea anchor of parachute type, the horizontal movements of relative ship's head bearing was sinuous to the wind direction and the towing rope with a period of about 10 minutes or so. The vertical movement was measured by recording depth meters. The observations were carried out chiefly in regard to the maximum depth, the floating periods, towing tension, and arrangement of weights on various speed. The results showed that the tension related to the nearly square of speed. Generally, the longer towing rope has a tendency to decrease the horizontal movements, dip of horizon and unexpected tension. The bouy rope which length is 20〜50 meters was demanded in order not to sink the sea anchor of parachute type.

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When beam wind and current are experienced the ship is drifted by them, so to proceed on the intended course, we have to revise the ship's head as much as the lee way. But it is difficult to measure correctly the lee way in no time. In this report, the author calculate the track of a ship that heads to a narrow entrance, revising the ship's head as follows: 1) the revised angle to the ship's head are φ+θ 2) φ is the measured angle of the lee way. 3) θ is the angle between the centre line of a narrow entrance and the line to the centre of the entrance from the ship's position. The θ at optional time is given as follows: [numerical formula] k_2…the speed of the ship's fore and a'ft drift θ_0…θ at the initial time. β…k_2+Vcosφ α…k_1-Vsinφ k_1…the speed of the ship's athwartship drift V…ship's speed φ…the measured angle of the lee way L…distance to the centre of the entrance from ship's position at initial time t…time from the initial time And the correct angle to be rivised for the lee way is given as follow in case of k_2=0: [numerical formula]

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In order to recognize some statisical characters of avoiding act, author analyzed the record of "Coarse Recorder" of DW 120, 000 ton tanker, which was putting on the line between Japan and Persian Gulf. There were considered avoiding acts of 338 cases which had ever been practised in Ocean, Malaca Strait and Persian Gulf during 140 days, that is, her voyages of four times. And author quantitatively got a few statistical results regard to following items about avoiding act (1) The Number of avoiding act practised in a watch (2) The Direction, Grade and Pattern of an avoiding act (3) The Transverse shifting distance & proceeding in the acts

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During the preceding years 1964 and 1965, we carried out a series of the model tests on the sinkage of very large vessel through the channel. The details of the work had been already shown in the reports compiled at the last year. The present report was described on the full scale measurement of the bow sinkage, which was down in the shallow water of Abu Jezza Flat (off Mina Al Ahmadi in KUWAIT) in Persian Gulf, during August and October in 1966. The water depth of the locality was in the region of 22m. The actual actual ship tested is "Tokushima-maru" of N.Y.K. Line (D.W. 123,989t). The change of bow sinkage was recorded by Echo-sounder receiving the echo from the water level foreward 13.35m from FP of the vessel, and the change of trim was measured with U tube of 230m long. Then, we estimated the maximum bow sinkage of the actual large tanker by this full scale measurement.

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An attempt is made to establish a simple diagram for the approximate calculation of the distance and time required to stop a ship from any ahead speeds by using her various backing powers. This time three diagrams are prepared for only the supertankers of more than 40,000 D.W.T.

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Conventional log carriers in the lumber trade for major coasting service and the proposed log barge system are compared in order to judge their relative merits from a commercial stand point. As a result, by the use of the log barges with log loading crane and side-tipping arrangements to load and unload, it is suggested that port time will be reduced greatly and each barge can therefore make more trips in a year, thus ensuring that the improvement applied to economy of transportation will be attained.

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The authors reported formerly about the time research of the liner boat on a berth. In that paper, they pointed out that the most effective counter-measure will be shortening of anchoring hour for rationalization of ship operation. In consequence, it should be increased the loading rate for the reduction of the term of one round voyage. It will be very difficult to keep a high loading efficiency by ship's excellent loading faculty only. The loading rate will be affected not only by ship's conditions but also outside conditions. For instance, the rate will be varied by cargo flow to the ship from inland deposit. There are two representative cargo lanes. One of these is on the quay with a transit shed using a fork-lift truck and another one is on the water using a barge. The loading rate using a barge is low degree. Accordingly, it should be eliminated the cargo through the barge as much as possible. Recently, they tried the statistic investigation on the connection between the loading rate and the mixing ratio of quay and barge cargo on the Yamashita and Center Pier at Yokohama harbour. Rasults: (Fig.2-2, 3-1) y_1= 58x_1+123…Yamashita Pier y_2=35x_2+139…Center Pire where Y_1, y_2…Loading rate (T/Gang-shift) x_1, x_2…Mixing ratio (P/B) P…Tons of quay cargo B…Tons of barge cargo There are some differences in these two equations but the mean value of loading rate of samples have become entirely equal to 157 T/G-S at each pier. The average hook cycle is about 2〜3m.p, c. on a loading of break-bulk cargo under the ideal condition. Consequently, the upper limit of y may become to 240〜360 T/G-S. The value of x should be increased up to 1〜1.5 at least making high loading rate.

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Investigations were made on the vessels fishing with long-line or floating-gill-nets concerning the above mentioned 'carrying of an additional light', with the questionnaries answered by 186 fishing vessels. According to those answers it was ascertained that the number of the vessels carrying the light was no more than 4.8% of the whole ; the reason of which was brought under researching investigations and the following items were clarified: -(1) During the fishing the direction of the gear is under perpetual changes, which makes it difficult to keep the light carried right to the direction. (2) Even when the light is kept right to the direction, it is not always easy to discern the direction of the gear by the guidance of the light. (3) The small sized fishing vessels are generally low masted, and illuminated with high-powered working lamps ; which makes it extremely difficult to discriminate the carried light from others. (4) On the contrary, there is the possibility that the carried light may be misunderstood, which may incur some dangerous accidents.

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Among the numerous factors which affect on the probabitity of the maritime distress, the bigness of the ship is very important. The actual probability of the maritime distress (Y), correlate with the gross tonnage (X) in some restrieted range, as follows. Y=aX^n or logY=loga+n・logX Constant (a) and exponent (n) of several kinds of distress in some statics are shown in table 1.

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Some problems to Vessels taking refuge from a submarine Volcanic eruption are studied in this paper. 1. Vesseles under way or at anchor may be endangered in the following cases. A. Direct hit by Volcanic bombs or mud eruption. a. Eruption at a center crater or a parasitic crater. b. Eruption in a radial fissure or regional fissure. B. Lava flows or mud flows. C. Tidel wave…(tsunamis) 2. Marinars should exercise caution when encountering with: a. Hot water disturbunce, b. Mud flows. c. Pumice flows. d. Drifting lumbers by Volcanic tsunamis. e. Extrusion of spine or lava dome. f. Volcanic big waves.

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