In thc Sea-areas along the Oceanic front (boundary of water masses) or of current-rips and tide-rips some very dangerous zones for sea-farers occur on the stormy days Several remarks for such cases and proposal for future researches in this line, especially for the theoretical and experimental studies of mechanism of pyramidal waves or crossed-sea due to the superposition of wind and current with the variation of bottom and topographic features.

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昭和30年9月15日午前6時42分、A丸(総トン数7611トン)が、ヒリツピンのBlack rock pass.の北水道を東行中に、北緯12°18'10"東経123°48'40"の地点で、図載12.2メートル水深の至近のところに水深7.1メートルの浅瀬を発見した。当時A丸の吃水は、船首6.75船尾7.94メートルで、排水量15980トンであつた。

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During the War, the Aero-Navigation Tables (Astronomical Navigation Tables, abridged) and Alt-Azimuth Ephemeris were published by our H.O., The purpose of these tables were to simplify the calculations within the error of 2'-3', which balances with the errors of determined positions of ships in ordinary navigations.

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It is customarily required by surveyors to set wooden ventilators among rice bags carried by sea. Besides the researches made by the present authors there has been made no measurement or discussion of the quantitative efficiency of wooden ventilators and stowing methods of rice in bags in the ship's hold. Many of the changes in the quality of the rice may be the effects of the solar radiation, the temperature of sea water, atmosphere and ship's shell plates and the air condition in cargo spaces. The authors tried to find a better method of stowing bags of Burma rice and their proper management during the voyage. They measured the humidity, temperature, air velocity and moisture ratio of rice, setting many measuring points in and out of ship's hold. They noticed the following facts. 1. The temperature of the upper deck plates rose as high as 60℃ in the daytime and the heat flux into the hold reached 190Kcal/m^2.h. and there was almost no changes of the temperature inside the cargo throughout the voyage from Burma to Japan, though the temperature fell considerably as the ship neared Japan. 2. There was some air flow inside the wooden ventilators at all times through the voyage. And its average velocity was 0.1m/sec〜0.7m/sec. The velocity of the air flow was as great as 2m/sec inside the trench in the cargo. The continuous air flow inside the wooden ventilators, however, had little or no effect on the cargo temperature. 3. There was no gain of moisture ratio of the rice, either. But some condensation of moisture was seen on the skin of the ship, inevitably caused by the cooling down of the ship's shell plates near Japan. We can say that there was no changes of temperature and moisture ratio of rice in the ship's hold throughout this transportation from Burma to Japan.

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The problem of spare bunker is a great concern not only Engineers but for ship's master. In case of a shortage, the master will be the one blamed and special attention, therefore, should be given for it. Generally, it has been accepted that 25 percent of fuel in excess of contemplated needs was sufficient quantity. The said figure, howerer, cannot be applied in all cases and should be figured out in accordance with the kind of ship, route and season respectively. The weather is the main factor to contrilbute to sea margin and in the following, a certain suggestion to the question was offered by vessels engaging in the North Pacific Ocean trade.

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Estimation of the nearest approach is one of the most important problems at the navigation with Radar. An attempt already performed to determine the nearest approach by a kind of nomogram, but it seems to have many disadvantages. We contrived more convenient nomogram (the Radar Plotting Diagram) for the determination of nearest approach, by which one can obtain it at once from the value of R_1, R_2 and β without any calculation, where R_1 is the first range, R_2 the 2nd and β the change of bearing. An accuracy of the nearest approach is function of the values of R_1, ΔR_1, β, and Δβ etc. (ΔR_1 is the probable error of R_1 and Δβ that of β), and one can easily see it by the formula and curves shown in this paper. Examples for selected values of R_1, ΔR_1, β, and Δβ etc. are also shown. The nomograms for the relative speed Vrel and the time T requied to arrive at the nearest approach from the first observation are shown. By these Radar Plottig Diagrams and data, one can obtain rapidly and acculate the necessary values for Radar navigation.

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It is well known that the gratest care must be taken of the treatment of the chronomter. As an experiment of the case where the chronometer is treated most carelessly, we tested several times what effect would be produced on the daily rate immediately after the day on which the winding was forgotten full one day. From the results of our experiment and the reference materials offered by Kobe Marine Meteorological Observatory, the following points were clarified. (i) The daily rate which appears on the day following the day when the winding is forgotten is always larger than the mean of the common daily rates in the absolute value, and takes the same sign with the latter. (ii) The value of the daily rate which appears on the day following the day when the winding is forgotten is almost constant on each chronometer, but considering generally, this value cannot be estimated before the winding is forgotten, becsuse the ratio of this value to that of the mean of the common daily rates is unsettled. (iii) Excepting the chronometer having especially high efficiency, the effect of the forgetting to wind upon the daily rate may extend not only to the next day but also to the following few days ; The fluctuation of the daily rates which appear on the following few days, however, is comparatively small and not worthy of notice.

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In the last paper, we treated the errors of line of position that is plotted on the Mercator's chart and found that the error due to the convergency of meridian was most severe for the high latitudes. At this paper, in order to exclude this error, we get the stereographic projection from the conditions of conformality for polar representation. We investigate the characters of the errors of line of position on this projection arising from: (i) the length of intercept taken from the latitude graduation, (ii) the position of the terminal of intercept plotted as straight line, (iii) the azimuth of position line plotted perpendicular at the terminal of straight line intercept, and (iv) the line of position as approximation of the circle of position. The resultant effect to the fixed position is sufficiently small for the ordinary air or surface navigation at higher latitudes, for example, less than one mile for latitude 80°, and less than four miles even for latitude 60°. For the polar navigation, we adopt the pole itself as an assumed position and can easily plot the line of position without computation. A simple correction table for the curvature of position line is provided, which can be used for the whole polar region higher than latitude 85°.

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From the point of view of the analysis of the motions of ships in the sea, this is the study on the maneouvering of ships in rough sea. On the solutions for the linear differential equations of ship's motions, given some conditions and simplified, for instance, assuming that the ship is underway in regular sea, then it is given the comparatively simplified equations for relations between the ships and sea. 1) According to the above equations, author defined the critical ranges of the motions of ships and made the diagrams for the relations between wave periods, angles of wave encounter and tuning factors. 2) And, author defined the critical conditions of the relativity of ships motions for sea surface. For an instance, author calculaed and discussed about the ship's data in table 1 on above items.

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It is considered one of the important functions for transformers to investigate the accident of marine transformers. According to the results of my survey on Japanese vessels, I have found that 5 accidents break out every year, and the marine transformer oil will deteriorate in 4 or 8 years since it began to be used. Therefore we should examine transformer oil, and overhaul the inner part of transformer once every four ycars. in that case, it is necessary to change transfarmer oil, when in bad condition. And it is a good idea to examine oil colour once every year.

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In order to obtain the calculating formula of the turning circle of ship, it is assumed according to the results of turning trials of actual ships and model experiments that the turning angle and speed of ship in turning is expressed by linear and exponential function of t, the turning time, respectiveley. Then following formulas are obtained, by integrating the product of above two functions with respect to t, and changing the variable t to θ. [numerical formula] Where x: abscissa (or Transfer at θ=π) in m.. y: ordinate (or Advance at θ=π/2) in m.. t_0: putting time of the helm angle in sec. k: ratio of final speed and initial speed. m: direction coefficint or angular velocity in radian/sec. θ: turning angle in radian. n: speed decreasing coefficient of exp. function. V_0: initial speed in m/sec.

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The safety of a vessel and its crew frequently depends on knots and splices used in joining lines together. In using lines, the breaking strain on the rope proper is plain enough, while the reliable data in joining ropes have not been well known. Therefore we have been to examine their strength on various methods in joining fibre or wire ropes. This time we investigated how many tucks each strand should splice in wire and manila rope splicings.

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Using the test tank of anchor and cable which is established at the Kobe University of Mercantile Marine, the movement of anchor and cable is showed its details through the measurement instruments. This paper is its third report which is showed stockless anchor and cable moving data ; Viz: (1) Holding pull effect at var. cable length. (2) Holding pull effect when let go anchor with moving ships head, etc.

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Sea-water are good electric conductor which disolved much inorganic salts, therefor, the electric corrosive worked all the time on the ship's hull. If coating films interfere with the electric current, it is a way prevent from the corrosive. Then, the auther tried to experiment that measured to electric resistance of coating films and corrosion of the iron piece. From there results may be draw a conclusion that the following. (1) Owing to the better anticorrosive effect for eiectric corrosive etc., we get at the painting has much influence. (2) The electric resistance of coating films are affected by the vehicle.

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We have recently come to use the phthalic alkyd resin paint in painting many ships. To test the adhesion of the paint on prime coats the auther studied on the experiments of painting on some prime coats and also of drying time of the primers. As the result, the marine zinc chromate primer is suitable for the paint and it is desirable that the drying time of the primer is one day to a week.

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I, as a representative of Apex Sangyo Co., Ltd., would like to emphasize that pest control in the ship is one of the most important problems for raising up efficiency of ship operation. The insecticidal lacquer is newly-born weapon for insect control mainly for cockroaches which the most of ships are infested as much as rodentia. Insecticide called "Dieldrin" which is contained in this particular lacquer has a remarkable residual effect which we have never found in other insecticides. Since it has been considered difficult to have complete kill of cockroaches by cyanide gas fumigation accomplished in compliance with present Quarantine Regulations, I, therefore, am sure that this insecticidal Lacquer be suggested to be hired in addition to the said fumigation performance. After several field experiments, another thing to be emphasized by the lecturer is, on above reason, rat control by cyanide gas fumigation and insect control with various sorts of insecticides should be considered separately, since insect extermination requires long-lasting residual effects. Ingredients of the insecticidal lacquer is as follows ; Hexachloro-octahydro-epoxy-dimethano-naphthalene (Dieldrin) Benzene Hexachloride (BHC) Solvent (Clear lacquer) Vinyl-resion solution [numerical formula]

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There is no question that officers and crew should attend deligently to their duties and persevere in their efforts to progress the technical skill. Furthermore, for the purpose of safe and efficient operation of ships, the need of technical mutual understanding between all departments in the ship must be recognized, because a ship may be thought as an organism. Between Deck and Eng. dept., there are some technical problems to be understood each other in connection with abovementioned matter, and it is indispensable to inquire them from the practical point of view. As the first step of inquiry, we have tried to ask some questions on the subject matter to the students of Kaigi Semmon Gakuin, including the Correspondence Students, and made investigation principally based on their answers.

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The energy requirement of the seamen was investigated. The calory consumption for a seaman on board the diesel boat and the coal burning vessel were 2535cal. and 2737cal. respectively.

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The Correspondence Course for Ship Officers was established in Kaigi-Semmon Gakuin in 1951, and its aim is to give knowledge and technical skill necessary for deck and engineering officers. In this paper, we shall report the result of our recent survey on the actual condititions and opinions of the correspondence-students. According to the survey, generally ship officers under 35 years old the main source of the students, and they consist of the graduates of all seafarers' educational institutions in Japan and others. Such content as useful to fulfil their duties successfully is supported as the aim of compiling text-books, Such instructive activities as question & answers, reports and schooling are to be taken up more positively. On the educational management, the speciality of ocean-going ship service is to be fully considered. In conclusion, it is important to realize "a correspondence instruction of the ship officers, by the ship officers, for the ship officers".

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