This paper gives the general velocity potential due to unsteadily moving blade in the water field with free surface from the stand point of the accelerated potential theory. The General expression of the velocity potential φ is given in §2.

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The effects of ship form on the frictional resistance are calculated on the basis of the turbulent boundary layer theory.
The stream is confined to be 2-dimensional, the effect of gravity is neglected. The boundary layer is assumed to be completely turbulent from the begining and the form effect is expressed as the ratio of the coefficient of frictional resistance of ship (C_f) to that of flat plate (C_f0)-the boundary layer of the flat plate is also assumed to be completely turbulent.
The calculation of the turbulent boundary layer is worked out in accordance with Bun's method.
At first, the ratio of length to breadth is maintained to be 7.00 (const.) and the water plane area coef. is varied, and then, the latter being maintained approximately constant, the ratio of length to breadth is varied.
The forms of ship water plane in the Z₁-plane are attained from the following equations
1)Z₁=Z+ma²/Z+na⁴/Z₃ n=-1+4/3m
the ratio of lengh to breadth=7.00
2) Z₁=Z+ma²/Z+na⁴/Z₃ n=1-m/3
where Z is put to be ae^iθ, that is, these ship forms are the conformal representations in the Z₁-plane of a circle in the Z-plane.
If the frictional stress is assumed to be 0 at the rear portion of the separation point, the calculated results are as follows.
1) m=.74 .76 .78 .80 k=1.203 1.174 1.145 1.122
2) m=.70 .80 .85 k=1.158 1.122 1.087
where k=C_f/C_f0 C_f=the coeft. of frictional resistance for ship form =R_f/ρLV², L=length of the ship. C_f0=d0. for flat plate.
These values are closely in accordance with the results of more elaborate calculation obtained by Okabe, the member of the Research Institute for Fluid Engineering, but in the range of small length-breadth ratio, the agreement is not so good, showing the fact that the form effect is not satisfactorily explained with the length to breadth ratio and the coeft. of fineness.
The k values agree approximately with the results obtained from the experiments of usual ship form models.

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1. When the curvature of the surface of a ship is everywhere small, the following equation of motion is obtained, assuming that within the boundary layer, the pressure does not vary in the normal direction to the surface.
u∂u/∂x=-1/ρ∂p/∂x+X+ν∂²u/∂y² (1)
The X-axis is in the direction of stream line, the y-axis in the direction of surface normal, u the velocity of the stream, p the pressure of the fluid at y=δ(δ=the thickness of boundary layer) and X is x-component of gravity. ρ & ν is the density and the kinematic viscosity of the fluid respectively.
Take ζ-axis in the direction vertically upwards, the following well-known relations are obtained.
p=const-ρV²/z-ρgζ X=-g∂ζ/δx
where V=[u]y=δ and g is the acceleration of gravity.
The equation (1) is then transformed into the form
u•∂u/∂x=∂/∂x(V²/z)+ν∂²u/∂y² (5)
Therefore, if the distribution of fluid velocity, and the form of stream lines are known for potential flow, the solution of 2-dimensional cases will readily give the distribution of tangential stress etc. along stream lines. The equation (5) also show that the effects of gravity come in evidence in the form of dynamic pressure only.
2. According to above mentioned idea, a calculation of boundary layer thickness at free surface was worked out. The result, show good proximity to experimental values.
Corresponding to the velocity increases & decreases at wave surface, the thickness of boundary layer has thin & thick values, the rate of growth of layer fluctuates about some positive values.
3. Assuming the variation of fluid velocity in the vertical direction, the distribution of tangential stresses, the frictional resistance etc. were calculated about a cylinder of parabolic waterline (L/B=16.5).
The frictional resistance along a stream line has a tendency to increase near the free suaface and the total frictional resistance is about 4% greater than that calculated on the basis of Froudes method.

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At the squatting or critical speed, the bow begins to rise and the stern to settle abruptly, and the increase of ship resistance happens at the same time. Mr, Wigley and other researchers calculated the wave resistance by the Michell-Havelock theory; those conclusions agreed with the experimental results very well even at speeds beyond squatting. Hitherto the effect of trim on the ship resistance has been slight, and Mr, Taylor expresses in his work that the rapid change of trim is a symptom rather than a cause of resistance.
From the same point of view the “shallow-water effects” had been analysed by the Michell-Havelock theory, and it has seemed as if this theory solved the cause of increasing resistance. But in the case of the “restricted-water effects” this theory yielded results that differed widely from the experimental results. On one hand Mr, Kreitner dealt with this subject by the one-dimensional theory and explained the wave that is in advance of the ship. This Kreitner's theory could not also explain the increase of ship resistance.
The author developed a new theory for the restricted-water and explained the cause of the increase of trim. Then he verified that greater part of the increase of resistance is the resistance by
R_??_ρgVδ/L, where V=volume of displacement, δ=increase of trim, L=length of a ship.
Moreover the author pointed out that the resistance based on the trim or based on the unsym-metrical local disturbance is a possible phenomenon in shallow-water and even in deep-water.

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The author has carried out the theoretical investigation of the symmetrical fluid field of a nozzle in his previous papers. This paper shows an analysis of the fluid field of the nozzle which travels in an oblique direction. In this case, trailing vortices depart from the trailing edge of the nozzle and these cause an induced drag of the nozzle.
The author shows a simple method to calculate the induced drag of a nozzle in this paper.

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The Author performed the Open-tests of the Blade-Wheel-Propellers with the orthodox Voigt-Schneider drive and a lever-crank drive, which are designed by the theory reported by him formerly.
The results of experiments agree with the theory resaonably.
The propeller design charts are drawn from the test results.
The Blade-Wheel-Propeller with the orthodox Voigt-Schneider drive is superior about 5-15% to that with the lever-crank drive.

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To utilize the energy of the rotation, existing in the slip stream behind a ship, the reaction rudder has been used commonly. But it seems that there is no reasonable method of designing this rudder. To improve the propulsive efficiency of single-screw ship still more, we investigated the action of the reaction rudder, and obtained a theoretical method of determining the chief character of this rudder
Relating to this investigation we measured the distribution of the direction and velocity of the slip stream behind a ship model at a self-propelled condition, and as a example, by means of the above-mentioned method, the optimum reaction rudder is designed for that condition.

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Contrarudder を装備した船舶の准進性能の理論的研究の中, 単独推進器-contrarudder の組合せにおける性能計算を行つたもので, 実船における計算例の結果は, contrarudder を有する場合は普通型舵を有する場合に比して, 従来実験的に確められていたように約1～3%の推力の増加が理論的にも確められた。

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Firstly the author considered, for the sake of simplicity, the case of a prolate spheroid and a sink propeller abaft, both advancing in a same direction of axis at fixed immersion under the free surface, and then he obtained theoretically the change of flow around the spheroid due to the suction of the propeller, which had been unduly neglected as small in the former theory of mutual interference, in the form of power series distributions of source and sink.
Then he calculated the resistance augmentation by the theory of wave resistance, and finally, discussed some interesting conclusions coming from the numerical results obtained.

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In order to obtain the necessary information for designing the propellers of fishing-boats, the mean wake fractions at the propeller position were measured by the means of blade-wheels on twenty-six models, in which the volume-length ratios, prismatic coefficients and breadth-draughtt ratios are varied systematically within the following range.
Volume-length ratio ∇/(L/10)3=7.5_??_15.0
Prismatic coefficient φ=0.55_??_0.75
Breadth-draught ratio B/T=2.2_??_3.0
The range of speed in the experiments covered from 0.20 to 0.38 in Froude's number, and from the results obtained the effects of the above factors of hull forms, speed, trim and vertical position of the propeller center upon the mean wake fractions were studied.

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As regards the bending strength of the rectangular plate, stiffened by beams, with elastically built-in edges, we can refer strain energy method by Mr Okuda and Mr. Arima⁽¹⁾, and direct method by Mr. Fujii⁽²⁾. The author, in thelast paper, presented general theory and those numerical examples of the rectangular plate, when torsional rigidity of stiffeners ignored, under the conditions that two opposite sides of the plate are simply supported and the other two opposite sides
simply supported or buit-in, which are parallel with the stiffeners. In this paper, he presents the general theory and those numerical examples of the plate in the consideration of not only deflexional rigidity but also torsional rigidity, under the conditions that the two opposite sides of the plate are simply supported and the other two oppositeseides are elastically built-in, which are parallel with the stiffeners.
Foot Notes:
1) Katumi Okuda and Takasi Arima: “Streng th and Frequency of Natural Vibration of Rectangular Plate with Longitudinal and Lateral Stiffeners” Jour Soc Nav Arch, Tokyo, 58 (1936), p. 59-78 & 59 (1936), p. 163-178.
2) Chuji Fujii: “Rectangular Plane Plate and Beams”

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As regards the free vibration of rectangular plate, stiffened by beams, with elastically built-in edges, we can refer strain energy method by Mr. Okuda and Arima⁽¹⁾, and slope-deflexion method by Mr. Suhara⁽²⁾. The author, in this paper, presents theoretical treatise in which he expressed the reacting forces and moments of the stiffeners or boundaries by the impulsive function of o-th or lst oder, and obtained the characteristic solution and the value of homogeneous partial differential equation of the rectangular plate, under the conditions that the two opposite edges of the plate are simply supported and the other two oppositesides elastically built-in, which are parallel with the stiffeners. And he showed some numerical examples of them.
Foot Notes:
1) Katumi Okuda and Takasi Arima: “Strength and Frequency of Natural Vibration of Rectangular Plate with Longitudinal Stiffeners”, Jour. Soc. Nav. Arch., 58(1936), p. 59-78, & 95(1936), p. 163-178.
2) Jiro Suhara: “On the Stiffening Effect of the Parallel Bar-Stiffener against the Free and Forced Vibration of Plane Plates.”

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塑性論の境界値問題への適用は, 弾性成分を無視した場合や, 一軸応力, 捩れ, 中心対称の如き簡単な場合に行われているに過ぎない。著者は塑性変形理論の立場で一般の二次元境界値問題の解析法を提案した。本方法は弾性歪と塑性歪が何れも無視出来ない弾塑性問題に有効である。独立変数としてx, yの代りに共軛複素数を採用することは計算を著しく簡易化し, 又等角写像の導入も容易にする。
解析は摂動法に基づいており, 第0近似は弾性解に相当する。例として円孔を有する薄い無限板が無限遠で一様な張力を受けている場合を解いた。
結果によると, 円孔の最大引張応力の集中度は外力をますと弾性解の値3より次第に減少するが, 最大圧縮応力の集中度は1より殆んど変らない。円孔側部の引張応力は円孔の辺より僅か離れた点で最大となることは注目に値する。残留応力は円孔周辺で圧縮応力を残し, 円孔の側部で円孔半径の25%外方までは圧縮応力が生じ, それより外方では引張応力を生ずることが判つた。

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In the previous papers, we have studied, theoretically and experimentally, the thermal and residual stresses under one and two dimensional stress distribution and followed up the causes of the residual stresses for each cases.
In this report, let us deal with the shrinkage stresses of circular cylinders rapidly cooled in water from uniformly heated condition, as an example for the case of three dimensional stress distribution.
To avoid the effects of the transformation stresses, we used the low carbon steel and the heating temperature was hold 600°C under the transformation temperature.
Three kinds of test cylinders were made, and the diameters were 40, 50 and 60mm respectively; however the length of each ones was constant 150mm.
We measured the cooling temperature at the outer surface of the test cylinders and the residual stress distribution by Sachs'method. These results are plated Fig. 2 and 8 respectively.
To analyse these experimental results, we calculated the temperature distribution at each moment as shown in Fig. 3, and obtained, by plastic calculation, the maximum plastic deformation, which will occur in some part during cooling. This maximum plastic deformation, components of which are expressed by gr, gt and gz in this paper, becomes the cause of constraint to the residual stresses.
The residual stress distribution can be obtained as a special case of thermal stress during the cooling of the test cylinder by using the respective stress-strain relations for the elastic and plastic zone.
The theoretical stress distribution is shown in Fig. 6, and the residual stress due to heating and cooling can be calculated theoretically with sufflcient accuracy, not only for one or two dimensional stress distribution but for three dimensional one.

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About the corrugated bulkhead on ship's construction, we have first defined its elastic modulus and rigidities, then solved the deflections of it using of consideration substituting that bulkhead with orthogonal aerotropic plate and compared them with those of experiment. We can, at the results, decide the method to be useful for its approximate calculation. As we cannot, however, determine the deflection so easily as expected by it, we produced at last other more simpler formula than that of former method taking advantage of the effective width.
After applying this formula to calculate the deflection and stress, then comparing them with the experimental results we have obtained some final conclusions about that bulkhead.
(1) The beam having section of one pitch wave with which the corrugated bulkhead is constructed, generally may be thought being that of simple beam theory if it has the effective width of the point at which the maximum bending moment would be happened, through all length of that beam.
(2) Stress for lengthwise direction may be solved being such a problem as that determined statically or unstatically on simple beam theory.

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In the railway ferry-boat for the Aomori-Hakodate route, especially the “Seikan-maru” No 5 and other ships of the wartime type which followed it, serious damage has been caused to the hull part near the fender which is liable to strike against the quay-wall.
So that, the investigations are need for obtaining data for the theoretical designing of the ship structure near the fender by clarifying the impact force between the ship and quay-wall.
In this paper, the author gives a result of theoretical study on the pressure between the ship and quay-wall in contact, according to the Hertz's theory of impact.
In the hull part which is liable to strike against the quaywall, the equation of motion becomes as follows,
where η+αηⁿ=0 η is displacement of this part. α equals to C/Me. c is constant, or the rigidity of the hull structure, Me is effective mass of ship.
From the theory of contact, n equals to 1.35, then, solving this equation, he obtains the impact pressure between the ship and quay-wall as follows.
F_max=1.097 C^0.4255•(M_eη0²)^0.5745

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Stress distribution due to the distributed incompatibility is studied. Total strain (ε_x, ε_y, γ_z) which satisfies the condition of compatibility consists of two strains, the elastic strain (ε_x', ε_y', γ_z') and the additional strain (ε_x'', ε_y'', γ_z'').
The elastic or the additional strain does not satisfy the condition of compatibility by itself. Fundamental relations are as follows:-
(1) Strain
ε_x=ε_x'+ε_x'' ε_y=ε_y'+ε_y'' γ_z=γ_z'+γ_z"}(1)
(2) Condition of compatibility
∂²ε_x/∂y²+∂²ε_y/∂x²-∂²γ_z/∂x•∂y=0 (2)
(3) Stress-strain relations
ε_x'=1/E(σ_x-υσ_y) ε_y'=1/E(σ_y-υσ_x) γ_z'=1/Gτ_z} (3)
where σ_x, σ_y, τ_z}: stress components E: Young's modulus G: modulus of rigidity υ: Poisson's ratio
(4) Condition of equilibrium of stress
∂σ_x/∂x+∂τ_z/∂y=0 ∂τ_z/∂x+∂σ_y/∂y=0} (4)
The stress function F must satiafy the next equstion,
∇⁴F(x, y)=E•R(x, y) (5)
where,
∇⁴=∂⁴/∂x⁴+2∂⁴/∂x²•∂y²+∂⁴/∂y⁴ R(x, y)=∂²ε_x"/∂y²+∂²ε_y"/∂x²-∂²γ_z"/∂x•∂y} (5)'
R(x, y) will be called the incompatibility at the point (x, y).
The relation between the stress function and the stress components are,
σ_x=-∂²F/∂y², σ_y=-∂²F/∂x², τ₂=∂²F/∂x•∂y (6)
The general solution of Eq. (5) is,
F(x, y)=E/8π_??__sR(x', y')r'²logr'dx'dy'+B.H. (7) where r'=√(x-x')²+(y-y')²
B. H: Biharmonic function
The integration is performed over the domain ^S where the incompatibility exists.
(7) will be changed to,
F(x, y)=E/4π_??__sφ(x', y')logr'dx'dy'+E/4π_??__sη(x', y')logr'dx'dy'-E/4π_??_sξ(x', y')(y-y')logr'dx'dy'+B.H. (8)
where
φ(x, y)=ε_x"+ε_y'' η(x, y)=-1/2(∂x/∂y+∂γ_z"/∂x) ξ(x, y)=-1/2(∂x/∂y-∂γ_z"/∂x) x(x, y)=ε_x"-ε_y"} (8)
Thus the sress distribution due to distributed incompatibility can be calculated by the expression (7) or (8).
The distributed incompatibilit is equal to the distributed rotational dislocation and also equal to the combination of the distributed dilatation and the two displacemental dislocations.
Next the special solution convenient for the problem of axial symmetry is obtained.
Some applications of this theorem for the thermal stress and plasticity are also carried out.

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The test result of the usability of welding electrode is said to be liable to vary, when the test welder is changed.
The object of this paper is to verify the effect of individuality of test welder on the usability test result.
Usability test for 36 different coated electrodes made with the same core wire are carried by 3 welders.
These test results are then analysed statistically.
The matching theory is used for this analysis. a).
We confirmed that the test results performed by 3 welders are cnosiderablly agreed.
a) S. S. Wilks; Mathematical Statistics 1944

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“FERNMANOR” was built by “KAWASAKI DOCKYARD CO., LTD.” Kobe, for the order of Messers “FERNLEY & EGER, ” OSLO, NORWAY. She was the largest export oil tanker built in Japan since the end of the World War II.
The followings are the summary of building procedure of the ship.
Contract signed on Feb. 17, 1949 Laying of keel on Apr. 8, 1949 Frame erection on Aug. 19, 1949 Launching on Dec. 19, 1949 Delivery on Jun. 17, 1950
The most noteworthy points of “FERNMANOR” are:
In the 1st place, the tank capacity which has sufficient amplitude and being equipped with powerful cargo oil pumps; for instance, by making the engine room compact to the farthest extent possible, the tank capacity was raised to 26, 550M³ against the official dead weight, 18, 384 K. T. which enables to load different sorts of oil without much trouble. At the same time 2 units of Worthington cargo oil pumps, each, having a capacity of 500T/h×70M, give facility to handle the cargo oil speedily.
In the 2nd place, the ship has the most excellent living accommodations: as “FERNMANOR” is intended for tramper vessel, she is destined to navigate sea far from her home waters, cruising around all over the world. In consequence, her officers and crew are expected to remain on board for many months on end without viewing even a shadow of their native land, the ship is virtually their own home. To case their living, their quarters are designed to give them an utmost comfort, every officer, and even crew, has his own private room.
Besides, there are provided many spacious and comfortable public rooms, that is, Saloon, separate mess-room each for officers, petty officers, stewards, and crew. As for a smoking room, there are provided in addition to the Saloon, separate rooms for officers and crew.
Especially in consideration of the fact that this ship, being the 1st large export ship, and liable being criticized by the World wide shipping interest, the designing and appointment of her living quarters were concentrated to make the quarters highly comfortable and livable.
In the 3rd place, her solidity of hull against 5877T steel weight, 866, 000 pieces rivets are planted and the welded length runs to 98, 100M.
However by the request of owner, the steel weight was made to exceed the rule by 150 tons. Besides there exists an undesirable factor as being in excess weight, comparing with the weight of other large type oil tankers built in this country nowadays.
Nevertheless, the ship in agreement with the desire of the owner was completed as a 30% welded ship, to which all our past experience and learnings were in corporated.
Especially every possible care and precision was given to make the tanks absolutely oil tight, the utmost care also was paid to give the superstructure its constructional symmetry and suface beauty of finish.
By looking back the building stages, the most important ones can be sequenced as follows, Aquirement of steel-Frame erection-Tank test-(Launching)-Outfitting-Testing of equipments-Sea trials-(Delivery)
These stages involved untold number of difficulties, but what was present in our mind at all time was completing the ship worthy of praise as the 1st large epxort ship.
Fortunately, we could secure the full satisfaction of the owner, and the ship was delivered officially to him on June 17.
We are fully convinced of her that she would not defame the reputation of Japanese ship-building under the strict and unreserved criticism of the world. It is our utmost pleasure that we can report you our success with a pride. Her particulars are as follows:
L×B×D 168, 000×21, 600×12, 000M.
d 30′×4.4″ (9.256M)
G.T. 13, 233.92T.
DW 18, 384K.T.
Rated speed at full load condition 14.853KTS
Main engine 7, 000 BHP KAWASAKI M.A.N. D7Z72/120P

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