Research on bulbous bow ships¹

Subtitle: Part I.A. Still water investigations into bulbous bow forms for a fast cargo liner

Article type: Research Article

Authors: van Lammeren, W.P.A. | Wahab, R.

Note: [1] Communication of the Netherlands’ Research Centre T.N.O. for Shipbuilding and Navigation.

Abstract: 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.

DOI: 10.3233/ISP-1966-1314201

Journal: International Shipbuilding Progress, vol. 13, no. 142, pp. 163-180, 1966