In this paper, the author tries to explain the present status of several point about the electric welding in America.
1. The welding schools.
After going the general description about the welding schools, he picks up three typical ones and describes their constitution, accommodations aud course of training.
2. Qualification of the welders.
Three sets of specifications are explained, i.c. those published by the Navy Depart-ment, the Building Code and the practice adopted by the Westinghouse Electric & Mfg. Co.
3. Strength of weld.
The numerical values for strength given in the above mentioned rules are explained.
4. Welding machines and welding rods.
The kind of machines and rods which are actually used in several shipyards and the makers of machines and rods are treated.

View full abstract

In the first part two dimensional potential flow round latticed wing is investigated and a new solution was arrived at. The second part is the application of the above theory to propeller. Under the supposition of plane cross section of propeller blades, the effect of mutual interference of blades upon thrust, torque and efficiency is discussed. The effect of interference has tendency to decrease all of them. The amount for thrust and torque hi almost same and hence the efficiency is almost unchanged. For large blade angles the interference is larger than otherwise.

View full abstract

The paper deals with the writer's personal opinion and advices to Japanese Ship-builderson the organization of the ship designing department and for the duty and training of chief designers.
Some improvements in warship and merchant vessel designing departments are in the extreme need for the future development of the Japanese Shipbuilding Industry and for the production of much superior vessels. Various scientific investigations in the design of ships are strongly recommended.
The qualification of the chief designers is discussed, while the extension of the right and duty of the chief designers is proposed and their authorization and confidence are considered very necessary.
The lack of capable designers should be fundamentally made up by the most careful and systematic training of young ingenious naval architects, and the talent of the young generation should be much esteemed.

View full abstract

The completion of the M. S. Tatsuta Maru, the sister ship of the Asama Maru and the biggest motor liner of almost wholly a Japanese production, is an important event for Japanese Shipping and Shipbuilding. On this remarkable occasion, it does not appear to be wholly nonsense to make some reference about these ships.
In this paper, a short review is made about the vast designs and long efforts to arrive at the final elaborate design of the Pacific Liners.
Some results are also picked up from those of the exhaustive trials, and finally, an attempt is made to lay out 2, 000 B. H. P. geared Diesel installation for a high speed Trans Pacific Liner which might come into question in future.

View full abstract

A simple method of drawing ship's lines is explained and it is pointed out that the surface of a ship can be determined by two directrices. Varying the directrices systematically, nine aft-body forms are fixed and they are tested in conjunction with the same fore-body. The resistance of these forms are compared. To obtain informations for designing propellers, the mean annular wakes of these models at the position of propeller are measured and compared.

View full abstract

This paper deals with the designing method of anti-rolling tanks of three types as shown in Fig. A on the theoretical basis.
The main principle for design is that the rolling of ship with tank is surely less than that of the ship with tank checked, so far as the period of wave is less than that of the ship itself.
As for the Frahm's type, the theory given by Woollard is adopted, and therefrom the designing method is developed. The procedure is as follows: let the curve of m(=amplitude of rolling/max. effective wave slope) be drawn with the abscissa e(=period of ship/period of wave) for the rolling with tank open and checked respectively as in the figure on page 10. Then the three conditions are obtained to find the three parameters, i. e. the size and the period of the tank, and the damping in the oscillation of tank water. The conditions are,
1. The value of e, for which the max. m occurs on e>1 side, coincide with that, in which m_μ curve intersects with m_μ=0 curve as M' in the figure.
2. The amplitude at M' is equal to that at e=1, that is, m₁'=mo.
3. The amplitude of oscillation in tank water corresponding to this period of wave for M' must be a given value.
The three parameters are found so as to satisfy these conditions, and the results of calculations are given in Fig. 6, from which, if the height of the tank is given from the constructional stand point (n=max. amplitude of oscillation of tank water/max. effective wave slope), the period(f=period of ship/period of tank), the size (μ=% of loss of metacentric height due to the free sur- facesof the tank) and the damping(b_t=2×extinction coef. of free oscillation in tank/π) can be easily found with the max. rolling angle(m=max. rolling angle/max. effective wave slope).
In this method, the effect of the position of the tank is neglected as secondary.
For Foerster's two types, the new theory is established in each case, but their actions are quite similar, only differing in the resistance to the motion of water in tank. The rolling angle for variable e is shown in Fig. 7, where μ means the same as above. From this figure, it is observed that the max. rolling occurs at e=1 so far as e_??_1, and by this fact, the relation between the maximum rolling angle and μ is obtained and given in Fig. 8. The resistance to the motion of water in tank affects the curve of Fig. 8. very slightly, and is safely neglected for designing purpose. As for the size of the hole which connects the tank with open sea, its determination is much affected by the resistance, and for that purpose the formula is given for the known value of the resistance, which must be experimentally determined in each practical case.
Lastly, the three types are compared, and the author's opinion is that the Frahm's type is better than the others on the practical point of view, if it is suitably designed.

View full abstract

1. The object of the research is to find some proper means to determine a very small quantity of petroleum vapour in air, so as to prevent the explosion danger, for instance, in the holds of an oil-tanker.
2. On measuring the refractive index of the petroleum vapour, the authors have found that it has so high a value as 1.0015. Taking advantage of this physical property, the authors introduced for the analysis of a very weak mixture the Doi's refractometer* which is manageable for even a novice. By means of this instrument the petroleum vapour content of about 1/10, 000 (by volume) could easily be detected.
3. Actual explosion tests were carried out on five kinds of gasoline and crude oil in the market. The higher and lower limits of inflammability were determined both by refractometer reading, and whence deduced by calculation in usual volume percentage. The lower limits of various samples seemed to coincide roughly.
4. Upon these, the possibility and the merits of the refractometer for the analysis of air-petroleum mixture are discussed, and the instrument is recommended for such practical purposes as for the case of the oil-tanker.
* Sc. Instr. from I. P. C. R., Tokyo, No. 33; Jap. Pat. 73 953 (1927).

View full abstract

This paper is a report of the launching of M. S. “Tatsuta Maru.” In this paper the author states the plan and calculation of the launching and then goes to the following items, viz;
Launching speed:
Method of estimation.
Comparison of the estimated speed and the actual one.
Frictional coefficient between the ways.
Starting force.
Method of the launching drag to be taken by The Nagasaki Dock Yard.
Publication of the results of his investigation carried out basing upon his own actual measurement of the position of lift by stern, and measurement of the pivoting pressure.
Result of the calculation of the longitudinal strength during launching.

View full abstract

In this paper the author describes practical methods of the application of the electric welding to hull constructions which he studied at Maiduru Naval Dockyard. First he explains about the electrodes, welding apparatus and the welders of the yard, and then about some tests in which he compared the welded cons tructions to the rivetted ones.Finally he describes his experiences with several examples.

View full abstract