Research on bulbous bow ships¹

Subtitle: Part II.B. Behaviour of a 24,000 DWT bulkcarrier with a large bulbous bow in a seaway

Article type: Research Article

Authors: van Lammeren, W.P.A.^* | Pangalila, F.V.A.

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

Note: [*] Superintendent of the Netherlands’ Ship Model Basin

Abstract: The propulsive performance, the bending moments amidships and the motions of a ship model representing a 24,000 DWT bulkcarrier were measured in smooth water and in irregular long-crested waves, over a speed range corresponding to 10 knots through 16 knots. The model was tested with a conventional bow and with a 9% bulb added respectively. In the loaded condition and for the speed range considered with smooth watertests, no saving in power was measured for the model with the bulbous bow in comparison with the model with the conventional bow. In ballast, however, smooth water tests showed that a reduction in power was obtained for speeds above 13 knots when the ship model was fitted with a bulb [3]. The waves in which the models were tested correspond to long-crested irregular head seas, windforce Beaufort 6 with a significant wave height of 2.90 m and an average period of 7.2 seconds. In the ballast condition for the sea described, the model with the bulbous bow still required less power than that with the conventional bow to attain speeds above 13 knots. Only small differences in bending moments due to rough seas were measured between the two models and hardly any difference in pitch angle. Smaller amplitudes of the relative motion of the bow were measured at the model with the bulbous bow when it was in loaded condition. In the ballast condition the average immersion of the propeller was reduced by the bulb.

DOI: 10.3233/ISP-1966-1313701

Journal: International Shipbuilding Progress, vol. 13, no. 137, pp. 3-13, 1966