The author calculated the equation of the terrestrial geodesic line and the distance between two points on the line. Let L: longitude l: geographic latitude θ: reduced latitude tanθ=b/a<tanl> a: terrestrial radius on the equator plane b: terrestrial radius on the axis Equation: -[numerical formula] Distance: -[numerical formula] s: distence

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When surveying over the scope of the problems with regard to the safety of anchoring, above treatise must be dealt without any thought that is of secondary importance, which was much emphasized R.L. Danforth as recently as 1945, for it has been well known empirically that shock on riding cable, which is most interesting and important in maintaining good anchoring, is caused by vertical motion of the ship. Fundamental consideration in this paper is due to the theory of small oscillation in conservative system, and transformation of the system is made easier by shifting H_1=const line to equi-potential line in vertical plane of ship's motion. Our treatment make clearer formation of shock on riding cable, but in conclusion, we dare emphasize, at the risk of over simplification that this influence is relatively smaller in heavy storm than in ordinary storm, etc. but without any contradiction to R.L. Danforth's report.

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The auther has studied on the shifting of weights on board when ship rolls and on the rolling of ship listed caused by shifting. The following results have been obtained: -(1) The shifting force be obtained by the equation of motion (1), and "the angle of repose" depends largely upon the shifting coefficent and the position of weights on board as shown in Fig2. Then it is necessary to consider how to store the cargo and to put the shifting board on her roots. (2) When a ship has a list by shifting weights, she roll on each side about that list and at the begining of rolling by the action of wave and wind, she rolls much to that permanent list side, and weights shift to list side increasingly, so we must manoeuvre to avoid the shifting by alter her course for wave and wind. (3) Maximum inclination occures when the rolling by wave and wind action matchs to the shifting of weights on the same side, and the list angle by the shifting of weights grows to be twice the statical inclination. And the inclination by the wave mt. grows to large on small period, ratio so it is important to change the encounter period by moderate manoeuvering.

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From the point of view of Mechanical Statis, when a ship is mooring with anchor and cables in water, the cable makes catenaries. The equation of catnaries is given: as following [numerical formula] σg: Unit weight of cables gr/c. m. T_0: Horizontal force on cable Hence, the investigations were undertaken to find out the relation between horizontal force on cable to catenaries by the experimentary methods. From above mentioned relation (the results of experiment), this paper described about the relation between holding power of anchor and cables to the force worked on ship about the cable run out.

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The following experimental formulas about the damping curve were obtained by our last experiments of magnetic compass bowl, which was reported on Journal No.9. [numerical formula] [numerical formula] Calculation error is contained about 5% in t_i and 10% in P_i, when the card constant (Cn=(d^4/M)^<2/3>) is 10±5 or the simplest card contant (Cn=d^<3/8>/M) instead of Cn is 1±0.5. When the inner part of the card was hollowed out and the clearance has been made bdtween the float and the card, about mentioned formula must be corrected by the following expression. T'=T-kT'(D^3-D^3_0) t'_1=t_1-kt'_1(D^3-D^3_0) P'_1=P_1-kP'_1(D^3-D^3_0) The error caused by this calculation does not exceed 5%, except the breadth of the card is narrower than 1 centimeter. This formula will be used conveniently for the designer of magnetic compass.

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In the following sections, we will consider the diffrence between Rhumb line distance and Great Circle distance which we call Saving of Distance D. § 1. Saving of Distance on Parallel Sailing. § 2. Saving of Distance on Composite Great Circle Sailing. § 3. Great Circle Distance on Middle Latitude for the same D. Long. § 4. Saving of Distance for the short D. Long. § 5. Saving of Distance for the sfort D. Lat. § 6. Saving of Distance for the short distance Principal Results. (1) Saving of Distance on Parallel Sailing for the same D. Long. Take the maximum value at Lat, 50°〜55°. (2) Within about 10' is Saving of Distance on the case of Composite Great Circle Track taking Lat, about 1°20' lower then vertex Latitude as Limiting Latitude.

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In order to distinguish the mark of the calcurated azimuth N or S, navigators have used "the tabb of the altitude on the prime vertical" complaining that this method is too troublesome through the process. Considering this point, we have newly devised a simple method in which they should use a diagram on the plane of the observer's celestial meridian instead of the above table for the same purpose, and then in this paper we shall introduce the new method in anticipation to the practical navigation. I Summary explanatron of the new method with an example (Refer to Fig.2 & Fig.3) Problem: Celestial body=Fixed star "Altoir", Hour angle=301°7', Latitude=25°58' N are given. Find the mark of the azimuth N or S. Solution: Plot Altair's position on its dotted line (repr: diurnal circle) according to given hour angle. Take the zenith on the outer circle (repr.: observer's celestial meridian) according to given latitude and draw a straight line (repr.: prime vertical) from the zenith to the original centre (repr.: E or W point). Then Altair's position is southerly from this line, therefore the mark of the azimuth is "S" II Excellent points of the new method in comparison with the former. (i) In spite of the marks and quantities of declination and latitude, we can directly distinguish the mark of the azimuth to the effect of saving time. (ii) At the first glance we can easily get the relation between the celestial body and the observer ; through the process, therefore, we have no fear of insecurity and can avoid unexpected mistakes. (iii) This diagram rather have the higher accuracy than "the table of the altitude on the prime vertical".

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A running fix may be in error unless the course and distance are correctly estimated. If there is no current errors inherent in running fix are due to the error of the log, the Compass error and the error of plotting. In above case the relative error of position which is due to the inaccurate distance is equal to the relative error of the log, and the error is due to the inaccurate bearings are given by following formula when considered that errors of two bearings are equal, [numerical formula], where Δa is the error of the position, Δθ is the error of bearing given by radian, l is the distance run and α is ***acute angle of the bearings. If we admit the error of position in one mile, the limitation of the acute angle is 10 degrees. When there is current the errors of the position depend upon the amount of the current and set. If the current is perpendicular to the first bearing the error is greatest and parallel to it, the error is nill. In the Case of 0<θ+φ<π, the actual position is near the object and in the case of 2π>θ+φ>π, the actual position is father out. Here, θ is the bow angle of the first bearing and φ is the direction of the current against the Course. If we admit the error of the position in one mile, it desire to avoid advancing the position line more than 30 minutes when we estimated the current is 2 knots.

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The effect of Marine Radar have to be studied synthetically from various points of view. One of them, the writer, from a view point of regular service of steamship, investigated samples about under way time of State Connecting Steamers between AOMORI and HAKODATE for the purpose of comparison of under way time and tests of percentage of delay, which depend on the Marine Radar equiped on ship or not. THE RESULT: The MARINE RADAR makes a contribution concerning maintenace of Regular Run.

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Using the test tank of anchor and cable which is established at the Kobe University of Mercantile Marine recently, the movement of anchor which is lain in the water bottom is showed its details through the measurement instrument. This paper is its first report which is showed stockless anchor's foundamental data ; Viz ; (1) Shapes and weight (2) Fluke angle and weight proportion by means of holding pull amount.

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Supposing that dips depend on the temperature at the observer Tn and the one just above the sea-surface, we have obtained the heat conductivity of the lower atmosphere by observing the timely variation of dips. As the results we have got the order of magnitude of b^2D as 2×10^<-2>〜3×10^<-2> hour^<-1>

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"Trim" is to be defined as the inclination of a vessel in a fore and aft direction. I have pleasure in introducing a very simplified trim gauge observed easily fine inclination of a vessel on this paper.

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I have created a new type of mechanical torque amplifier by new idea and succeeded to apply this mechanism for controlling of a rudder of small ships such as catcher boats or tunuafish boats etc. This system is guickly changeable to either manual or mechanical stearing according to desire. Using this system, human stearing torpue was amplified about 40 times easily.

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