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A description is given of construction and equipment of the shallow water laboratory of the Netherlands Ship Model Basin at Wageningen, inaugurated on April 16, 1958. Aim and planning of this new facility are specified and the various parts are described. Finally a few suggestions are made for possible future developments and an increased contact with practice.

This paper presents the results of an extensive research into model test technique and the extrapolation problem in shallow water. These results enable us to examine the necessity for the use. of a method of three-dimensional extrapolation for shallow water. Experimental data on wall effect have been obtained by carrying out tests according to the method of images in a pressure-tight shallow-water basin. With the aid of a three-dimensional extrapolator the wall effect has been divided into effects on frictional and on wave-making model resistance. The results of the wall-effect tests were compared with the Kreitner theory and the influence of slots between tank walls and an adjustable bottom was analyzed. The results of propulsion and overload tests are given. Finally the correlation between model tests in shallow water and full-scale trials on a lake and the river Rhine has been discussed.

A description is given of the design and the construction of a special seakeeping laboratory, in which ship models can be tested in regular and irregular waves of any given direction. By means of a wave generator which was developed recently, the possibilities of imitating actual conditions at sea have been increased as compared with the facilities in existing basins of the conventional type.

This paper deals with the resistance- and thrust-measurements on a series of nine geometricall similar Victory ship models, ranging in scale from 160 to 18, and on a Victory model boat of scale 6. The first part of the paper gives a description of the ship, the propeller, the models, the test apparatus, the test performance, the instrument calibration and the necessary corrections. The measured resistance and thrust values of the model boat are correlated with the results of the tests with the models using three methods, i.e. the Schoenherr, the Hughes, and the Lap-Troost extrapolators. The results of experiments for the determination of the wall-interference are given. These experiments are on the principle of the “image method”. An attempt is made to analyse the thrust deduction factors as a function of the Reynolds number. Conclusions and a programme for the continuation of the tests are presented at the end of the paper.

The paper deals first with the deficiencies in the theory of wake-adapted ship screws. Next, a method of design for these screws is discussed which, by starting from the available data of the circulation theory, has been developed with the aid of experimental data in such a way that the screw design satisfies the requirements with regard to correct pitch and cavitation properties. Using this method of design, a series of 4-bladed wake-adapted screws has been calculated. The appropriate design charts are provided, and a numerical example given. For readers not acquainted with the fundamentals of the circulation theory a brief review of the screw design according to this theory is given in the appendix.

The deficiencies of cavitation tunnels of current design, where screw propellers are tested in a homogeneous velocity field, are discussed. A description of a new design of a tunnel is given, where propellers can be tested in a homogeneous flow as well as in velocity fields corresponding to those which exist behind the ship. A new method of carrying out cavitation tests and of dividing the ship’s propulsive efficiency into a number of components is suggested. The results of some comparative cavitation tests are shown. A few possibilities for future research are summarized, followed by a number of conclusions. The paper concludes with two appendices, in which some theoretical remarks on the inequality of the velocity field behind the ship are given together with the results of a number of systematic experiments for determining the relation between thrust and torque constants in the “open water” and “behind” conditions.

A description is given of the development and construction of a special seakeeping laboratory in which ship models can be tested in regular and irregular waves from any direction. By means of a recently developed type of wave generator, the possibilities of imitating actual sea conditions are increased as compared with the facilities in existing basins. The basin can also be specially adapted for tests at restricted water depths.

The research reported in this paper has been carried out to investigate the effect of large bulbous bows on the resistance and propulsion of a ship. The basic shape of the investigated bulbs was a sphere, connected to the ship in such a way that the original hull form was maintained as much as possible. The basic ship was a fast cargo liner of 150 m (500 ft) length. Her trial speed corresponds to about Vs/Lf=0.90. The application of a bulb of conventional size and shape would not favourably affect the resistance in the speed range of interest. The application of a bulb based on a big sphere, however, did reduce the required power at equal speeds. For the ship under consideration this reduction was 8.9 per cent. at Vs/Lf=0.90. The size of the sphere, needed to reduce the bow wave system as much as possible, was determined by a simple approximative theory. The experiments concerned in the first instance the location of the sphere relative to the bow, the effect of a variation of the diameter of the sphere and of the angle of entrance of the water lines of the ship. When the ship was fitted with a large bulb faired into a more conventional shape, the resistance curve of the ship obtained the character of that of a ship one or two knots faster than the basic ship. Finally the effect of a bulbous bow was compared with the effect of small changes in the main dimensions of the ship.

Model tests were carried out to determine the still water performance of a 24,000 DWT bulk carrier, provided with a large bulbous bow of hemi-spherical form. A comparison of the results with those of the same ship model, however, with conventional bow was made both for the loaded and ballast condition. Considerable savings in power were found for the ship with bulbous bow in the ballast condition. In the loaded condition practically no influence of the bulbous bow could be established. The results were checked on possible laminar flow effects by carrying out additional tests with extra turbulence stimulators. Flow observation by underwater television and flow tests with paint showed that separation of flow on the forebody did not occur. Overshoot manoeuvring tests have indicated that the manoeuvrability of the ship model is hardly affected by fitting the bulbous bow. A comparison of the maximum rates of change of heading at given rudder angles shows that there is only a very slight difference between the values of the model with conventional bow and those of the model with bulbous bow, which means that the bulbous bow has practically no effect on the directional stability either.

The paper describes a new facility of the N.S.M.B., in which manoeuvring properties and behaviour of ships and other structures in waves, current and wind can be studied. Design considerations and data concerning wave generators, pump installations and various other structures are given. A paragraph is devoted to instrumentation and the paper ends with a short enumeration of tests, that can be carried out in the new laboratory.

The development of facilities and experiment techniques at the Netherlands Ship Model Basin takes place along well-defined lines, which are described in the paper. The set-up and working methods of this institute are discussed. An idea about investments and turnover is given. The existing facilities, as deep water tank, cavitation tunnels, shallow water tank, seakeeping tank and computer centre are described as well as the high speed tank and the wave-current tank under construction. A brief review of the main experiment techniques is given.