Bahrein's middle body corroded badly after 13 years of service in carrying gasoline. The corrosion was so deep that the middle body became unfit for service and beyond restoration by ordinary repairs.
American Bureau of Shipping surveyed and condemned the ship as unfit for navigation in September 1934 owing to the result of the serious corrosion of her middle body.
Ship's owner, therefore, decided to take extraordinary measures to repair her by renewing her middle body.
Asano Steel Sc Ship Building Co. accepted the job and made the middle body and launched it at its ship building yard.
Old Bahrein was drydocked and her middle body was cut off. The new middle body was successfully fitted while afloat in a drydock.

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In the first part of the paper the authors described the towing-experiments of spheres of various sizes under varying depths of immersion. They calculated mathematically the wave resistance of a sphere and the bottom effect upon it, and compared them with those obtained by the experiment. The conclusions drawn are as follows :
(1) When the depth of immersion is large enough to avoid the surface effect, the relation between the resistance coefficient and Reynolds' number is analogous to the experimental results of the wind-tunnel within range of Reynolds' number between 1.5 × 10³ and 2.5 × 10⁶.
(2) The calculated values 'of the wave resistance of spheres, and of the bottom effect agree fairly well with those obtained by the experiment.
In addition the air-draw phenomena for small depths of immersion were minutely examined, an, d some explanations relating to the cavitation phenomena were given.
In the second part the authors investigated the resistance of spindle-form, and of analogous bodies by using the models of some fishes, submarines, and etc. Besides the study of the results of the towing-experiments of the models above referred to, they discussed briefly the law of similitude, and calculated the value of the wave resistance according to the authors' mathematical formula.
The deduction of the mathematical formulae are shown in the appendix.

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The authors examined the effects of depth of water on the resistance of ships by the towing experiments of warship models at several depth of tank water, and the following general conclusions were obtained :
(1) The resistance curve in shallow water shows a hump, and the shallower the depth of water, the lower the speed at which hump occurs.
(2) The trim of the ship changes abruptly at the critical speed at which the abovementioned hump occurs.
(3) Percentage increases of effective horse power in shallow water for ships examined by the authors are shown in Figs. 7 to 1G.
(4) It is impossible t find a general law for estimating the influence of depth of water on the resistance, as this amount differs considerably according to the principal dimensions and ship form in addition to the speed and the depth of water.
(5) The critical speed can be expressed by the following formula : -
D/L=k (v/√L) ²-k₁ (v/√L),
where D… Depth of water in m.,
v… Critical speed in m/sec.,
L …Length of the ship in m.,
k, k₁ … Constants having values shown in Table 4.
(6) Minimum depth of water at which resistance does not increase can be estimated roughly from Fig. 21 or Fig. 24 according to the length and speed of the ship.

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Up to the present, 17.5 kg/cm² G. and 365°C were the highest pressure and temperature in steam plants of merchant vessels, in this country.
The steam condition of 27 kg/cm² G. and 390°C was adopted in these new ships, where coal was the fuel, in order to improve the whole plant efficiency, also save weights and spaces of boilers.
The three main boilers are the Mitubisi three drum type marine water tube boilers, having the heating surface of 385 square meters each, equipped with the Taylor multiple-retort underfeed stokers for burning the Fushun coal, the horizontal type convection superheaters and the tubular air preheaters.
On the official sea trials of the S. S. “Oryoku-Maru, ” the whole plant efficiency of 18.9% was obtained.

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The behaviour of a panel of thin plate with initial curvature under compression differs from that of a purely flat plate, even if its buckling is taken into consideration. In this paper, the relations between the initial curvature, the compressive force, and the resulting strain in the direction of compression, are theoretically obtained by the energy method. By taking the definition of the effectiveness of a thin plate as the ratio of the mean compressive stress to the compressive strain multiplied by the Young's modulus, a simple method of its calculation is given for a given form of initial curvature.

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The present work is a sequel of the previous paper entitled “Boundary Stresses in a Plate having an Elliptic-Hypotrochoidal Hole.” The first part of this paper deals with the stresses in the vicinity of the hole which were overlooked in the above mentioned paper. The second part deals with the stresses in a plate having a reenforced part of several forms, in order to inferring the effect of stiffening members at the rim of the hole on the stress distribution. In conclusion, the author deduces the effect of coaming plates on the stress distribution of deck platings in the following degree. If the coaming plates are moderately strengthened, stresses round the opening (except in the immediate neighbourhood of corners) may be expected to be so small, that the thickness of the plating abreast hatchway need not be increased over that of ordinary deck platings. To the experimental verification of the above deduction, the author hopes to return in a later communication.

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On the assumption that the stress-strain relation in the tension test holds in the case of bending, the general theory of the plastic bending of a mild steel beam having a section, which is unsymmetrical to the elastic neutral axis, was developed. This theory was applied to some special cases of practical interest. As an example, ⊥-section beam and rectangular beam were numerically treated, and the moment-deflection relations in these cases were graphically shown, using the ratio of the lower yield point to the upper one as a parameter.
In the latter part of this paper, comparing the theoretical results with the experimental ones on the ⊥-section beam and the rectangular beam, the relation between the elastic failure and the stress-distribution, which is considered as an important problem in the plasticity, was discussed. And it was found that the elastic failure started from the outer-most fibre of the beam and proceeded into the inner part gradually. Accordingly, it can be seen that, if both of lower and upper yield points are taken into account, the older theory of failure, in which the elastic failure is considered to have no connection with the stress-distribution, is consistent with the experimental facts.

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With wood blocks, ship-models and ships the following experimental investigations were carried out :
1. rotating axis and rotating resistance,
2. pivotting point and rotating resistance in turning, and then with a ship-model the experiments of advancing and rotating resistances in turning were carried out by a new small turning experimental tank.

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Forced vibrati ns in a vessel are attributable to many causes, and those due to the main engine and propeller have the most remarkable effect. Vibrations due to the unbalance of the main engine have of late been considerably reduced with the advance in knowledge concerning design, and it is now not impossible to eliminate those which are produced by the reaction of torque, by means of a torque reaction balancer. However, as regards the vibrations caused by propellers, until recently there have been no means other than those conservative or passive methods which can only reduce, vibrations, and such are not of much effect.
The author conducted investigations into the causes of vibration in the S. S. “Nagasaki Maru” and “Shanghai Maru” in the year 1929, and discovered that the propeller was responsible for the vibrations and that there was a great variation in them, depending on the phase difference of the rotations of the propellers on both sides. To prevent these vibrations, a phase synchronizer was invented by the author, which is the subject of this paper.
Investigations have been continued since then of vibrations in vessels, with the result that the author found a great variation in the vibrations of twin-screw or quadruple-screw vessels, and confirmed that they came from the main engines or propellers The gear in question has recently been adopted for the first time in the new Shimonoseki-Fusan Cross-channel Ferry Boats of the Imperial Government Railways, the “Kongo Maru” and the “Koan Maru”, and actual results are now available.
In the present paper, the author gives the results of investigations on the relation between the phase difference of rotations the variation of vibrations due to the main engine and the propeller, together with an account of the principle and construction of the phase synchronizer as well as its actual performance results.

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The authors suggest a hydrodynamic method for damping the vibration of a ship. Submerged blades of moderate elastic resistance and inertia mass that are fitted to a ship's hull, are possible to fairly damp the vibrations of that ship for any frequency of the forced vibration, particularly in certain speed range of the ship. The nature of the problem is ascertained mathematically and confirmed through model experiments. It is shown, in some example, that the maximum amplitude of the ship (among different vibrational frequencies) with a damper, is merely 1/9 that of the case of no damper. The applicability of the result of the investigation to the actual case is also discussed.
The details of the problem as well as its theoretical and experimental treatments are shown in the Appendix towards the end of the paper.

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