International Shipbuilding Progress - Volume 8, issue 83

Authors: Swaan, W.A. | Vossers, G.

Article Type: Research Article

Abstract: Experiments have been carried out with a series of six models. These models had the same principal dimensions and displacement, but differed in section shape in the forebody and in prismatic coefficient. Results are presented from tests in head seas and in bow seas. Measurements have been made of pitch, heave, motion of the bow relative to the waves, thrust increase, and midship wave bending moments. It is concluded that U-shaped sections are advantageous as regards wetness, speed loss, bending moments and even as regards slamming on some occasions. V-shaped sections are advantageous as regards motions, especially in waves …longer than the ship (i.e. for small ships). Furthermore, it is found from the experiments that decreasing the midship coefficient is unfavourable in regard to wetness and the tendency to slamming. To reduce speed loss a low midship area coefficient is to be preferred for fast vessels and a large value for slower ships. Experiments with a model having extreme flare above water in the forebody showed only a small influence on the motions. The extreme flare, however, made the model much more susceptible to slamming. Show more

DOI: 10.3233/ISP-1961-88301

Citation: International Shipbuilding Progress, vol. 8, no. 83, pp. 279-301, 1961

Authors: Vossers, G. | Swaan, W.A. | Rijken, H.

Article Type: Research Article

Abstract: In this paper results are presented of a systematic programme on the influence of principal dimensions and block coefficient on the midship vertical and lateral bending moments. The models form a related family and have been chosen in accordance with the Series 60 lines. The models have been tested in regular waves with five different lengths and five different wave directions; all tests were carried out at one given wave height and one given weight distribution. The results of the tests have been made dimensionless and diagrams are given from which at four different Froude numbers the following variables can …be read off: still water vertical bending moment due to forward speed, vertical and lateral wave bending moment variations, phase angle between vertical and lateral wave bending moment and shift of the mean value of the vertical wave bending moment. As an example of the use of the diagrams a prediction of the stresses in the deck edges due to the combined action of lateral and vertical wave bending moments is given. Finally a comparison of the measured values with the results of statical calculation is made. Show more

DOI: 10.3233/ISP-1961-88302

Citation: International Shipbuilding Progress, vol. 8, no. 83, pp. 302-320, 1961