This paper includes the results of the tank tests of a systematic series of the MAU-type five-bladed propeller models with the high pitch ratio, and the extended design charts of the propeller series including the results mentioned above.

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Three dimensional photo-elastic analysis of the marine propeller blade was carried out to clearify the stress characteristics of the blade subjected to hydrodynamical forces.
Stress distributions in the blade obtained from photo-elastic method were discussed comparing with the calculated ones by Taylor's method and Shoenherr's method. Tension stress patterns on the face side in the cross sections showed considerably different features from calculated ones, while compression stresses on the back side nearly agreed with calculated ones.
The maximum stress on the face side in cross sections was observed in the vicinity of the nearly half point of the blade width. These features are not always completely explained from the influence of inclined neutral axis in bending, which is comfirmed also in our photo-elastic observations, and the influence of propeller pitch on the stress patterns was not outstanding in this range of the pitch ratio 0.6521.078.

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A practical method is described for calculating the non-lifting potential flow about a slender ship in steady horizontal motion at zero Froude number in shallow water. The present method is some expansion of the previous method for calculating the deep water flows past ship hulls described in author's previous paper. The method utilizes a continuous source density distribution on each surface of the infinite image series of a ship, and treats the normal component v_n, (or integral equation for the source density distribution), radial component v_r and circumferencial component v_θ of disturbed velocity as two dimensional problem, and treats the axial component v_x and veloctiy potential Φ as three dimensional problem. After the integral equations for the source density distribution are solved numerically, pressure distribution and added mass of a ship under various motions in shallow water are calculated easily.

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This paper presents a simple method by which we can calculate approximately but enough accurately added mass and damping of twin hull cylinder making a heaving, swaying and rolling oscillation on the surface of a fluid or we can calculate the wave exciting force working upon this twin hull cylinder when it is held fixed on incoming plane waves if we know those of one cylinder of the twin hull cylinder. And it is known from the previous paper by one of the authors that the accuracy of added mass etc. obtained by our method is almost complete.
Applying this method to some cases of twin hull cylinders, it can be concluded that the hydrodynamic interference between twin hull oscillating or in beam seas is not so small and accordingly we must not neglect this interference effect when we want to make a theoretical study of the motions of twin hull ship in waves.
If we can obtain the solutions of radiation problem for twin hull cylinder by ur method, then the equations of the motions of twin hull ship in head seas or beam seas can be formulated with the aid of the strip method. The solutions of these equations are shown to be generally in good agreement with the experimental results, but the motions of twin hull ship are different from those of single hull ship and this fact results from the interference effect between twin hull. This effect appears typically in the motions in beam seas and if we do not take the effect into account theory can not predict the motions of twin hull ship.

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Recently, the practical use of Transient water waves for Testing Ship Models had been shown by papers, (1), (2), (3), (4). But in making use of this wave, there are restrictions e. g. the linearity, the length of the time history, etc. So the control of Transient Water Waves is necessary.
In this paper, we restrict our attentions to the Concentrative Transient Water Wave (write T. W. W.) and tried to generate T. W. W. with arbitrary characters in frequency domain (Fourier Spectrum) and with arbitrary concentrating position. We considered further the estimation of wave profile of T. W. W.
Consequently, by making use of frequency transfer functions, we could show the method of the generation of T. W. W. with a practical precision. In this paper we showed two T. W. W. The Constant Amplitude T. W. W. is useful like the Constant Amplitude Power Spectrum of white noise. And the Constant Wave Slope T. W. W. has a good character against the wave breake down.
For the Concentration, to determine the sweep time by phase velocity is doubtful. By the experiment, we showed that the wave of an apparent frequency moves with its group velocity, and the T. W. W. moves with its mean velocity as a whole. So, the sweep time should be determined by the group velocity.
Then we explained roughly the concentration of T. W. W. by phase function in time domain. To control the concentration precisely, the transfer function must be introduced. So we proposed a definition of the concentration of T. W. W, in frequency domain by defining time length (T_l) of the T. W. W, and making it minimum. This definition seems to be appropriate. After that, the transition of the phase of T. W. W, was understood precisely, and the position of the concentration could be known exactly.
At the last, we showed the estimation of the wave profile by an arbitrary time history and the comparison with photos was made. From the calculated wave profile at the concentration, the wave break down seemes to be evaluated by the apparent wave slope.
For the limit of the wave height and the wave slope, a new experiment is now planned.

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In this paper, experimental confirmations of our approximate nonlinear theory on the shallow water waves which was previously published are reported. The results obtained are as follows :
In the range of ω<3 ω₀ (ω is the frequency of oscillations of the tank containing the shallow water and ω₀ is the natural frequency of the water), the theory sufficiently well represents the wave motions as well as the pressure relation that the bottom pressure exerted from the waves is equal to the static water pressure. The bore and the standing wave appear almost precisely at ω=ω₀ and ω=2 ω₀ respectively. The existence of the special combinations of horizontal and inclining oscillations of the tank where no wave motion is excited is also proved experimentally.
At higher resonances of ω=3 ω₀, 5 ω⁰ etc., wave motions are very complicated and appear to include the subharmonics having the frequencies such as 1/3ω=ω₀ for ω=3 ω₀, 1/5ω=ω₀ and 3/5ω=3 ω₀ for ω=5 ω₀ and so on, respectively. This phenomenon can not be derived from our simple theory. We became recently aware of Chester's elaborate works on the same subject as ours (he deals with the horizontal oscillation only), so we could not learn from him to our great regret.

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This paper deals with the motions of a high-speed container ship at sea, which is chosen as the prototype of the ships recently built in Japan.
The model experiments in regular and irregular oblique waves were performed in order to compare their results with those obtained by the theoretical calculations based on the “strip method”, not only as to longitudinal motions but also lateral motions.
The agreements between calculated and measured amplitudes of motions are very good for pitching, fairly good for vertical and lateral accelerations, good for rolling, while the difference is considerable in yawing.
The results of the theoretical calculations covering wide range of sea conditions are also represented as the contour maps of the amplitude, by which the effects of ship speed, encounter angle to wave and wave period on severe motions of the ship are discussed. As the results, for example, the cause of the large rolling motion which has been frequently experienced at such high-speed vessels in quartering sea is shown.

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The authors tried the theoretical analysis on the motions, hull surface pressures and transverse strength of a gigantic oil tanker in regular waves.
In the first place, the ship motions in regular waves from different directions were analysed by assuming the coupled equations of heaving and pitching motions and those of swaying, yawing and rolling motions based upon the modified strip theory. The non-linear roll damping was introduced into the latter coupled equations of motion.
In the second place, the hydrodynamic pressures induced on the hull surface were evaluated theoretically by using the solutions of ship motions.
Finally, the transverse strength calculations were performed for several cases of the ship in waves by using the obtained hull surface pressures and the estimated cargo oil pressures.
The large hydrodynamic pressures were found in beam and quartering waves, which produced the large bending moments at the deck corner, bilge and bottom of longitudinal bulkhead in the transverse ring.

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In the Part 1, arrangement of the new seakeeping basin, hydraulic wave maker and high speed towing carriage which were completed on March 1969, have been reported in detail. This part is devoted to describe main towing carriage and subcarriage built in 1970 fiscal year. The main towing carriage, of which the principal dimensions are 31. 68 m in width, 8. 050 m in length and 6. 209 m in height, moves longitudinal way above the rectangular part of new basin and the subcarriage moves transverse way on this main carriage.
Accordingly by manual or automatic control of both carriages, it is possible to make the subcarriage pursue a free running ship model and always stay right above it. Therefore, it is very easy to supply electric power to a model running on water surface without any restriction of motion, or to recieve eletric signal from the model and record it on the subcarriage. Moreover by moving both carriages simultaneously, it is able to make a model ship advance obliquely to the direction of wave propagation, and to measure the hydrodynamic force acting on it or its motion in oblique waves.

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The new method of this report is to be named PAL-test, because it employs several Parallel Alignment Lines, in navigational words, transit lines. If we measure only two series of data, namely time points of transits with a stop-watch, and ship's headings by a gyro-compass, while an actual ship is under stationary turnings across PALs, we can determine turning characteristics : angular velocity, turning radius, tangent speed, drift angle, pivoting point, and reach, advance, or transfer, tactical diameter of the ship, which are necessary to calculate the ship's path.
Full-size experiments were carried out with a 360 GT training ship, and the usefulness of the method seems to be verified. Parallel quay lines along waterways in the Port of Kobe port, instead of PALs were employed, therefore, the experiments were partly unsatisfactory due to other ship's disturbances. The author proposes some plan of PALs to be constructed for public use.

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Accuracy of the finite element solutions is due to discretization and round-off errors. The discretization error of the finite element method is closely related to the idealization of structures or the mesh pattern, and is investigated in the present paper. By expanding the displacements around a node, we can derive differential equations from the fundamental equations of the finite element method according to Walz, Fulton and Cyrus and the error terms can be obtained by comparison of the resulting equations with the governing equations. Such error terms govern the local character of the solutions ; if they are of higher order, the solutions form smooth surfaces and yield more accurate values of strains. This situation can be attained by regular mesh division. The method of expansion is effective to the expressions for strains, and it is shown that the nodal and edge averaging for strains yields accurate approximations in case mesh patterns are symmetric with respect to the node or the midpoint of the edge. The boundary conditions are also investigated, and it is clarified that they are less accurate compared with the field equations.

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In this report the strength of are carriers and ore/oil carriers is examined in order to establish their design basis. At first the method of calculation is established. The calculation is divided into two steps. First step is the calculation of stresses in case the relative displacement of longitudinal members are neglected. The second step is the calculation of stresses due to the relative displacement of longitudinal members. The stresses calculated by such method were found to coincide with experimental results fairly well.
Then the standard load conditions for both are and oil services are adopted among several typical conditions.
Analysis of the transverse strength of the are carriers and ore/oil carriers built so far was carried out under the said standard conditions.
Finally, considering the results of the calculation and also taking account of the specification of classification societies' rules, design stresses corresponding to such standard condition is determined.

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There are few literatures available on the calculation of the concentrated critical loads subjected to the edges of the reinforced rectangular plate. In this paper the author studied the problem by means of the energy method. And he calculated the critical loads and wave pattern when buckled.

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The eigen-values and dynamical stress distributions of the stiffened plate contained web frames are analyzed theoretically. As a numerical example, the free vibration of forepeak tank bulkhead of 67, 800 tons tanker, which arranged the web and ordinary frame alternately, are treated.
The effect of the aspect ratio of panel on the lowest eigen-value is very important, i, e. in the case of the large aspect ratio, both web and ordinary frame vibrate up and down in the same direction (case 1), but when aspect ratio of the panel is small, the web frames vibrate torsionally and ordinary frames make up and down motion (case 2), and when this aspect ratio becomes smaller, both web and ordinary frames vibrate torsionally (case 3).
The effect of the bending stiffness of the ordinary frame on the mode shape is hardly recognized for the case 1, but it becomes the important factors for the case 2 and 3.
The approximate calculation method of the eigen-value of the stiffened plate contained web frames is introduced, and the calculation results agree fair well with the exact solution.
The considerably high dynamical bending stresses concentrate at each joint of the plate and stiffeners.

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In a previous report, the plastic deformation behavior of a notched specimen welded between 60 kg/mm² high strength steel (HT 60) and mild steel (SM 41) has been investigated under static tension applied parallel to the weld line. Because of the asymmetry of specimen, however, it is difficult to estimate from the above experimental results the effect of a notch on the plastic strain behavior of composite weldment. In the present research, therefore, two kinds of notched specimen (SHS and HSH specimens) are used in which HT 60 and SM 41 are symmetrically arranged about the axis parallel to the direction of tensile load. Strains which occurred in the notched specimens have been analyzed experimentally by the use of strain gages and the use of a Moiré method, and stresses distributed on the net section of specimens have been calculated by incremental strain theory from the measured strains.
The strain concentration is more remarkable on the notch of HT 60 sides of the HSH specimen than on that of SM 41 sides of the SHS specimen. Since the stress redistribution takes place on the SHS specimen, the stress concentration at the root of notches is lowered after the SM 41 sides begin yielding. On the contrary, the stress redistribution does not occur on the HSH specimen.

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Many works have been done on the problem of end cracking in one side welding. To the authors knowledge, however, any attempt has not been successful in practice to change the temperature distribution during welding in preventing this end cracking. In order to establish effective means to prevent this cracking, the present authors carried out a series of experiments on one side welding accompanied by several kinds of countermeasures. They measured the position and length of the crack as well as the expansion of root gap and the final shrinkage across the weld. As a result of these experiments, it was confirmed that the end cracking could be prevented by countermeasures based on mechanical considerations. It was found to be especially effective to heat or cool the plate at proper position during welding.

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The brittle fracture initiation in butt welded joints of two kinds of 80 kg/mm² class high strength steels has been studied using wide plate specimens each of which had a surface notch along the weld bond and was given the weld angular distortion. Effects of the residual stress adding, the offset and the ACI (Anti-Crack-Intiating) beads on the brittle fracture initiation characteristics in such a specimen has also been studied.
It has been found that the residual stress adding made it easy at higher temperature for the specimen to failure under low applied stress and that the ACI beads shifted the fracture stress transition temperature to extremely lower temperature.
The effect of a offset on the fracture stress transition temperature was extraordinary remarkable, and has been clalified quantitatively by means of a newly developed K_I equation. This equation makes also it possible to express the effects of surface notch size, amount of angular distortion and another various kinds of conditions on the brittle fracture initiation characteristics of the welded joint.
Furthermore the effects of weld heat input and chemical composition of steel on the fracture initiation characteristics of the weld has been cleared through experiments and the K_I equation.

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In the previous paper, a pulsating tension test was carried out using wide plate specimens of mild steel with a central notch of stress concentration factor K_t to be 5 and 10. By simulating the cyclic behaviors of the strain at the tip of a notch to hour-glass shaped small specimens, the low-cycle fatigue crack initiation life of a plate specimen was compared with that of a small bar specimen. The results showed good correlation between the wide plate and the small bar specimen, but the life of the plate specimen with a notch of 5 in K_t was slightly longer than that of small bar specimen, while that for notch of 10 in K_t was slightly shorter. This fact shows that the crack initiation life depends on not only the cyclic behavior of strain but also the configulation of a notch.
In this paper, a same test was carried out using wide plate specimens and small bar specimens of mild steel and 50 kg/mm² high tensile steel, and the crack initiation life was investigated more precisely based on the present and previous results. It was revealed that dominant factors affecting the crack initiation at the tip of notch in the pulsating tension test are maximum strain at the first loading, strain amplitude, increasing mean strain and restraint of deformation at the tip of a notch. Since the influence of the restraint of deformation at the tip of notch can not be realized in the strain controlled test simulating the cyclic behavior of strain at the tip of a notch, the larger K_t of a notch is, the shorter the crack initiation life of the plate specimen is than that of simulating test on the small bar specimen. By comparing with the results of completely reversed strain-cycling test of small bar specimens, it was found that mean strain and its increase show supper posed effect on the crack initiation life when the life of the plate specimen is shorter than about 700 cycles. As for the effect of the increasing mean strain, an effect of the increasing mean strain was found to be appeared only when the increasing rate of mean strain is larger than about 0.1%/cycle, from the results of comparing test of linearly increasing mean strain with that of constant mean strain.
In this paper, two cumulative damage rules in low-cycle fatigue are proposed taking into consideration of four factors affecting the crack initiation. One is based on the cyclic behavior of strain, and the other on the cyclic behavior of notch opening displacement. These two rules are able to estimate the fatigue life of the plate specimen within a small extent of deviation.

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In the previous report, the authors studied the finite element method for large deflection and elastic-plastic analysis of plane frame works.
The behavior of the structure was analized by the incremental load procedure (Step-by-Step method). The incremental stiffness matrix of the deformed structure was derived from the principle of virtual work for an incremental theory taking into account the spreading of the plastic regions into members. It is possible to make analysis of the structure including both, material and geometrical nonlinearity by this method.
In this report, the authors treat numerical analysis containing the unloading process of plasticity (strain reversal), so that they can practice to determine the maximum strength (ultimate load) of elastic-plastic structures, and also to persue the behavior beyond the ultimate load by using this method.
Hitherto, many researchers have dealt with inelastic buckling strength and plastic behavior of compression members.
For the first numerical analysis the authors deal with the strength of eccentrically loaded column. with the rectangular cross-section, and compare the obtained results with that of Chwallas. Next, the experiment of H-section columns with small imperfections is carried out to investigate the elastic-plastic characteristics, maximum strength, and behavior beyond the ultimate load of the column. The theoretical and experimental results are in close agreement. Moreover, beam-columns under high axial load and moment. are calculated and discussed comparing with CDC's method and experiments at Lehigh University, relatively to next analysis of framed structures.
Secondly, the instability of elastic-plastic frame works is studied. This method is a general method to make it possible to solve easily the complex and multi-story frames, which, so far, have many difficulties in solving and computing the elastic-plastic behavior of unbraced frames including sidesway. To investigate the sidesway failure, the numerical analysis by this method is carried out for portal frames and three storied frame with large vertical loads with no brace, and compared with Prof. Wakabayashi's experiments and that of Lehigh University. There are good agreements between authors numerical analysis and these experiments.
The computer program formulated by this method makes it possible to analize 200 elements at most by the use of HITAC 5020 with short computing time. Therefore this method is quite efficient to the analysis of elastic-plastic planar frames involving instability and of determining the ultimate load of framed structures.

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In the previous papers, a relatively rigorous theory was presented with respect to the elasto-plastic behaviours of bi-axial bending beam-columns. An aproximate analysis deals with the same problem as above and a relatively simple interaction formula is proposed for the maximum values of forces and bi-moments. The formula simultaneously takes into account the danger of plastic collapse by bending and that of buckling by torsion-bending. It gives safety with respect to the results of theory and those of tests.

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This paper treats the transmission of the shock waves in beam structures.
Main contents are as follows.
1. The transmission of the flexural shock waves in an infinite beam is analysed from a standpoint of energy transmission and approximate solutions are obtained.
2. Approximate solutions are compared with exact solutions. When γ²/a²t>4, distributions of energy density in beams, envelopes of vibration amplitudes, and periods etc. obtained from exact solutions converge to the approximate solutions given in this paper. Even if the initial conditions of the beam, namely the initial shape and velocity shape of the beam, are arbitrary, approximate solutions of the beam response can be obtained easily by this method.
3. Shock wave transmission in structures composed of beams of different shape sections or corners are analysed using this method and compared with experimental results. In general, they were fairly in good agreement.

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The current engineering fracture criteria K_c, Φ_c and ω_c⁺ for brittle fracture initiation are critically reviewed analytically and experimentally.
The followings are obtained conclusively :
(1) The fracture initiation in existence of residual stress, say due to welding performance, pre-loading etc., is explained equally well by Φ_c or ω_c⁺ criterion, but not by K_c criterion.
(2) Φ_c criterion is refered to qualifying examination as a fracture criterion throughout the small & large scale yielding regions. It is confirmed that COD test on small specimen can predict the fracture behaviour of large specimen or structural member.
(3) The value of Φ_c is dependent on degree of triaxiality of stress or plastic constraint (notch acuity, plate thickness, structural constraint etc.) as well as temperature.

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Recent progress in fracture mechanics suggests the possibility of its practical application to the purpose of preventing the brittle fracture of steel structures constructed of ductile material such as ordinary structural steels.
One of the problems in determining permissible defect size, allowable stress level and service temperature on the basis of laboratory tests is the fact that fracture toughness values such as K_c or Φ_c are not material constants in a strict sense but rather variables depending on the intensity of mechanical constraint of the defective region of the structure.
When the deformation at the crack tip in plate thickness direction is highly constrained, multiaxial state of stress is developed, which is supposed to cause the decrease of fracture toughness and the increase of transition temperature.
This paper describes the results of an investigation on the brittle fracture initiation characteristics of severely constrained structural member using model specimen with a defect coupled with stress concentration, mechanical constraint and welding residual stress.
These three factors are considered to increase the susceptibility to brittle fracture initiation. Comparative experiments have been carried out using wide plate notched tension test (without three factors) and that with longitudinal welds (with residual stress) to clarify the effect of the three factors mentioned above.
Further the effects of pre-loading and cyclic loading at room temperature were investigated using the constrained model specimens.
COD concept was applied as the fracture criterion for the analysis of the test results.

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Brittle fracture initiation characteristics of a single notch or the correlation between the brittle fracture initiation temperature and the crack length at any stress levels has been evaluated by using the deep notch test specimens.
However, sometime two cracks might exist in the welded joint and the distance between these notches is so small that the interference should be taken into account.
In this paper, the effect of distance between twin notches or equi-length notches in a line being perpendicular to the applied stress on the brittle fracture initiation characteristics was investigated experimentally by using the wide plate test specimens with twin notches.
The length of through-thickness notch was 40 and 80 mm, and the distance between two notches varied from 10 to 160 mm. The steels tested was a 60 kg/mm² high strength steel and the specimen size was 20×400×500 mm.
In addition, the crack opening displacement (C. O. D.) at the inside and the outside tips of notch were measured by means of the electrostatic capacitance method which has been recently developed by the authors. The test results were compared with the theories based on the stress intensity factor and crack opening displacement.
When the distance between two notches, l, is less than the notch length, 2 c, the fracture stress decreases with decreased distance, l. However, when l is small, the fracture stress increases casually with decreased distance, where the fracture stress is nearly equal to that for a single notch in a length of overall length of two notches, 2×(2c)+l.

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Effects of stress-relieving heat treatment on brittle fracture initiation in welded structures are quantitatively discussed in terms of fracture mechanics. The basic concept employed for discussion is that brittle fracture should initiate when tensile yield zone formed ahead of a pre-existing crack attains a critical size depending on the material.
The critical zone size as a function of temperature is predictable from Charpy-V transition temperature. Metallurgical information on welding residual stress and Charpy-V data for various conditions of heat treatment is compiled and put into the proposed logical frame of fracture mechanics.
There is a divergence of conclusion for every case of steel type. Cases studied are those of an ordinary mild steel, two kinds of quenched-and-tempered high strength steels and a Mn-Mo steel for nuclear pressure vessels.

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The brittle fracture initiation characteristics can be evaluated by measuring the crack opening displacement (C. O. D.). Especially, it is very difficult to analyze the brittle fracture phenomenon of welded structures by computation, and the measured C. O. D. in the vicinity of crack tip is significant.
The authors developed newly a measuring method of crack opening displacement by means of the measurement of change in electrostatic capacitance caused by the crack opening. A sheet of foil strain gage as an electrode inserted in the slit works effectively for the measurement of change in clearance of slit.
By adopting this new method, effects of width of test specimen and slit were studied from viewpoint of C. O. D. experimentally as well as theoretically.

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In winter sometimes the icing of ships sailing in northern seas results from mostly the freezing of sea spray blown over them, which has led frequently to cases of capsizing due to extreme loss of stability.
The author trys to make clear the icing mechanism and develop the estimating method of the ice rate of growth on ships to be duly considered referring to the meteorological and sea conditions around our country.
This first report describes theoretical and experimental studies on the icing of cylinders.

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This report deals with the specific methods for modernization of the assembly line of the curved panel units.
One of the vital problems in the modern shipbuilding industry is the modernization by means of mechanization and automation, to overcome insufficient labor sources in the recent years, during the hull assembly process. Conventionally, the modernization of the hull assembly process has been achieved mainly by the automation of the welding, but it has been limited to be applicable to the flat panel units only. However, the hull, as its movements are much related to the stream-line, the adoption of the stream-line is indispensable, and the fore and the aft parts of the hull naturally include the curved panel units. These curved panel units usually are made up with three dimensional faces, furthermore, each unit has different shape and arrangement. For this reason, it has been considered impossible to apply the mechanization and the automation, and the assembly work has had to rely on the skilled workers, therefore, at present it requires more skilled workers than in the case of work on the flat panel units. Also, in consideration of adoption of the flow line production system for the assembly process, the work is often interrupted by the dangerous turn-over of the units for the safety's sake, which causes considerable occasions of waiting time, one of obstacles in the flow line production sytsem for the assembly process.
From the viewpoints mentioned above, the authors have conducted checkings for the modrenization in extensive fields of the assembly processes of curved panel units, and as its first stage, we developed the automatic assembly apparatuses for the curved panel, composed of the forming jack device, the welding positioner, and the one-side automatic welding machine.

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Recently all tankers should not discharge any oily water which contains more than limited value of oil, and mostly have to be arranged slop tank and adopt “Load On Top System” to cope with oil pollution. But, it is a very pity that we have not kept enough actual data of distribution of oil in slop tank during settling of oily water which was used to clean cargo oil tanks.
As the first step, we carried out following on-board test on the above item when the M. S. Jingu-Maru (about 138, 000 MTDW Tanker) was on her way from Japan to Persian Gulf.
The test was carried out in the duration, from May 1968 to January 1969. Consequently we got these distributions and effects by tank-heating, the type of suction pump and some emulsion-breaker during the No. 1 settling. Additionally we measured the thickness of surface oil in the slop tank, and carried out quantitative analysis of the surface oil gathered by sampling device through butterworth hole.

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This paper stresses the rapidity of change in today's world and underscores the necessity of learning to live with change. It points to probable future growth in the worldwide need for ocean transport and predicts the relative importance of various kinds of ships in meeting those needs. Trends in ship production techniques receive attention, as does the probable future demand for air cushion vehicles, hydrofoil craft, and other novel types of marine vehicle. The problem of air freight competition is discussed briefly. The place for education and research in a changing world receives particular emphasis.

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