We observed the time of ship's passage on a crossing line at the URAGA Strait. Meanwhile we measured the ship's speed. The author figured the above results on a diagram, of which the abscissa means time and the ordinate distance along the strait. Any slanting line represents passing ship, and the tangent of its slope corresponds the ship's speed. Any crossing point of the two slanting lines shows that overtaking has done at the time and at the place. If we know the distribution of the ship's speed, and if any ship maintains its speed whether other ship exists near her or not, then we can say how many times of overtaking occur in a unit time and unit distance in the strait. The author showed the above principle using the data at URAGA Strait, and the theoretical value coincides very well with the observed one.

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Since the speed and other quantities of ship dynamics are closely related to the ship length, L_<pp>, these quantities and the traffic capacity are sought as linear functions of λ(=LogL_<pp>). Starting from a linear representation of λ for the dimension of the effective area of ships, the maximum density of ship group, ρ_<max> is also obtained as a linear function of λ by assuming "solid sphere" potential. The traffic capacity is equal to the product of the maximum density and the speed, and hence, the basic traffic capacity, C^<co>_<basic>, corresponding to the probable values of the speed, V^<co>, is given as a linear function of λ. A small deviation of the speed from the probable value, V-V^<co>, requires a small correction to the function.

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We have made an investigation of ship's traffic in the Uraga-Suido for 10 days from 26th Aug. to 5th Sept., 1965, by means of the radar photograph and the visual observation. This paper described the above results on the traffic flow and its amount. It is pointed out that small vessels (under 500 G.T.) sway the whole amount of traffic (69%) and the movements of these small vessels show some characteristic and dangerous features on the traffic flow in the channel, concerning with the geographical arrangement of ports around the Tokyo Bay.

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A generalized criterion for measuring economic effectiveness, the total present worth of both invested costs and future returns was given as a extension of Benford's paper (1963). A block diagram was constructed that quickly shows the logical aspects of the process of comparing ships of different types, sizes, speeds and power plants in order to judge their relative merits from a commercial standpoint. Numerical calculations were also made for oil tankers ranging from about 20, 000 tons to 100, 000 tons in dead weight and 12 knots to 21 knots in sea speed.

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The Fishing vessels casualty occured by Typhoon 29th in Mariana, at eary morning, 7th October, 1965. According the TYPHOON WARNING, 10 Bonits fishing vessels anchored to refuge the typhoon at Agrihan Is. It was reported that the typhoon 29th increased in violence with the barometer 914mb. and wind velocity 70m/s. Unfortunately, 7 vessels of them sunk and 209 crews died. We had search the accident and obtained some lessons from the casualty as follows: -(1) Security of water tightness on fishing vessels. (2) Study for a weather reports and a course of typhoon at low latitude. (3) Improvement of a bait hold. (4) Handling of the main engine under the heavy weather, particularly on a variable pitch propeller. (5) Leadership and labor management.

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In order to prevent many shipwreck due to meteorological phenomena we must to improve the analysis technique of weather forecasting for vessels using by satellite data. In this report I investigated the mechanism of synoptic scale disturbance, fog and etc., by the observational data from meteorological satellite.

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To catch the day to day change of tropical disturbance and frontal disturbance is very important for vesseles undergoing. In this report I attempted to visualize the development of synoptic scale disturbance through the change of the cloud systemes as observed in APT pictures.

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It seems that the disturbance factors such as wave, wind and current are particularly significant for the determination of minimum time ship routing across the ocean. Then, taking these factors into consideration, the formulae of computation of the determination of the routing are evolved using the latitude-longitude co-ordinates on the assumption that the earth were a sphere, and also the routine of computation are presented in the form of flow charts.

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With rapid development of electronics, the miniturized digital computer will be equipped on a ship near future. Under necessities of astronomical navigation with a digital computer, programs of distance and initial and final cources have been set up and tested between two points on the great circle. According to HITAC 5020 (FORTRAN IV), compilation requires 7sec., and computation 0.2sec. each set of the distance and the cources. Computation is executed in 7-figure, the accuracy will be sufficient for astronomical obsernations at sea.

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This paper discusses how to compute hyperbolic lattices of Decca radionavigational system. 1, We decided the more adequate computational procedure instead of which has been used to compute hyperbolic lattices for charting, by HIPAC 103 electronic computer of our Hydrographic Office. 2. The error of estimated lattices due to uncertainty of phase velocity is investigated. Because we are demanded to compute hyperbolic lattices at sea around Hokkaido, but we have poor data on phase variation of signal in the 70〜130KHz band in the above area.

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To know the variation of the tensible strength and the elongation of fibre ropes, Manila, Vinylon, Polyethylene ropes have been exposed to the sun light and immersed in the sea water for three years and eight months. As the result, in the experiment of exposition, the Vinylon ropes have shown a better tensible strength and elongation than the Polyethylene ropes, but in the experiment of immersion, the latter has shown a better result than the former.

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Because of short of the utility and reliability, navigation equipments in automation ships are not so suitable for ships members, but increase burden. So we inquiry into the ratio of utility, necessity and reasons of the failure, found out as follow. 1. There are not so big difference between automation ships and others in navigation equipments. 2. About 77% of failures are caused by electrical and mechanical. 3. About 40% of failures could not repair on board. 4. In order to research the reliability of ship's equipments, we should record every troubles and its details of each ship.

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When two vessels are approaching one another, involving risk of collision and the standing on vessel continues to keep her course and speed, there are the extreme relative positions that the giving way vessel cannot avoid collision even if she is manoeuvred with crash astern or steered hard over. Hereupon the auther calls them the manoeuvrable limits. We replace a vessel with a circle of diameter equal to ship's length. If the two circles which represent two vessels intersect or contact with each other, thare is a high possibility that the two will collide. In this report, the auther calculates geometrically the process that two circles come to contact with each other and finds the manoeuvrable limits to avoid collision at sea in case of end on and crossing.

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The present paper deals with some experimental investigations on the yaw of ship in case of riding on a single anchor or of mooring, under the strong wind and high wave, carried out at the experimental water tank topped with wind tunnel. The main object of the present experiments is concentrated on the additional effect of waves. The important results obtained are summarized as follow: 1) The methods by which the motions of ship and shock loads acting on anchor cable can be eased and minimized, as proposed in the previous paper, are also valid for the present case. 2) The shock loads acting on cable are larger in wind and waves than without waves. 3) The extent of yaw of ship appears to be smaller in wind and waves at light loaded conditions, while larger at full loaded conditions, than in wind but without waves. 4) So far as the present experiments are concerned, in case of mooring, the effects of waves on the motions of ship at light loaded conditions are so complicated and indistinct.

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When a ship moves in shallow water, the hydrodynamic phenomena around the sides of ship cause the increasing of added mass moment of inertia of ship. This in turn affects on natural period of rolling of ship. This paper relates to some model experiments in respect to shallow water effects upon the rolling period of ship in still water. Tests were carried out for 3 models their principal dimensions are shown in table 1. As results of these tests, periods of rolliog are virtually increased in accordance with decreasing of water depth shown in Fig.1 & 2. For example, it is necessary to correct the rolling period of 20 percent or so in shallow water depth is twice the draft of ship.

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The ship's bodily sinkage caused by her passage through the restricted channel was the most important primary effective element to decide how much to need the bottom clearance for the safe navigotion of very large vessels. As the results of the tank test of ship's model (1m, 2m, & 3m in length.), we observed the following facts ; a) In the general type of very large vessels with a bulbous bow, the sinkage of bow was more than that of stern, and even if the depth of water becomes extremely shallow, excessive sinkage of the stern, what was called, SQUAT, did not occur. b) The initial trim had not so much effect on the mean sinkage, but only on change of trim underway. c) Though tendency of trim of the bow could be applied to very large vessels, it was done not always to other ships. d) Revolution of the model's propeller had not so much effect on the bodily sinkage. e) The bodily sinkage, tested at every various speeds in the restricted water, generally indicated the same tendency as values calculated by J. Kreitner's method.

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The previous paper of this series had revealed that the marine radar had small target but was available for detection of the dolphin bamboo shelter under the ordinary meteorological and oceanographic conditions. But the navigator should be aware of the critical conditions of the radar to pick up the target. This is due to the following possibility: They are frequently obliged to detect even small objects such as small fishing craft and floating part or marker of the fishing gears settled. These will usually have the target of small equivalent echoing area, consequently give fluctuating echo weaker than the rain or sea clutter echos. The above-mentioned facts meant that it is hard to neglect of the possibility of mis-detecting the small objects in these obstructive clutters. In addition, the detection range of target will suffer considerably from the reduction of the projected area of the target or the effect of the shadow sector due to the ships structure. The present paper dealt with the radar detection of the dolphin bamboo shelter in relation to either the relative direction of the shelter or the obstruction due to rain and sea clutters or to shadow sector.

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Concerning the probable circle, which is a method of expressing error boundaries of ship's positions, the writer has investigated the conditions in which the probability is 95% based on the probability integrations. In this paper, he reports on the method and results when the system is applied to error boundaries of ship's positions, and the isopleths presented here will help navigators to know easily and clearly the error boundaries of their own fixes.

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This paper deals with the present status of the international standardization of freight containers, with priority given to the dimensional element, including the national standardization of freight containers in U.S.A., U.K. and Japan.

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Concerning on the measurement of ship's motions in a seaway, 5 of ship's motions of 6 freedoms as a rigid body in a space, that is, rolling, pitching, surging, swaying and heaving, could be measured by newly deviced apparatus which consisted from Vertical gyro, Stabilized plate and Transducer for 3 dimensional accelerations. The block diagram of this apparatus is shown in Fig.2. The view of entire instrument is shown in Photo. 1 and also the stabilized plate with sensing elements is shown in Photo. 2. The example of the record of motions by this apparatus is shown in Fig.8. The maximum values of acceleration in heaving motions and its power spectra are indicated in Table 2 and Fig.9, respectively ; the later were computed by HIPAC 103 Electric Digital Computer in Center of Hokkaido University.

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Since old age the sea anchor is very effectrve to keep a small ship driffting in safety. Many reports which the sea anchor being useful, has been sent to us. Here the way of using sea anchor in storm or typhoon is mentioned.

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