International Shipbuilding Progress - Volume 29, issue 338

Authors: Latorre, R.

Article Type: Research Article

Abstract: Growth in inland waterway barge transport has resulted in a steady increase in towboat propulsive power. Use of ducted propellers, multiple screw installations and tunnel sterns has enabled this power increase. This paper concerns the trends in comtemporary, high-powered towboat tunnel stern design. Tunnel stern designs from over 60 towboats are used to develop empirical formulas characterizing the stern tunnel design. Tunnel flow angles Θ 1 and Θ 2 are then introduced for use in avoiding vibration problems from poor tunnel flow conditions.

DOI: 10.3233/ISP-1982-2933801

Citation: International Shipbuilding Progress, vol. 29, no. 338, pp. 252-259, 1982

Authors: Burcher, R.K. | McKendrick, G. | Price, W.G. | Stonehouse, M.

Article Type: Research Article

Abstract: A series of model tests are described in which steady state and oscillatory rudder derivatives are measured. During the experiments undertaken in a circulating water channel, the model ‘travelling’ at prescribed forward speeds was either restricted or allowed freedom to roll. The difference in the forms of the side force measurement records obtained from the oscillatory rudder tests are discussed with emphasis on the interaction between rudder and roll motions. In the steady state rudder tests the changes in the measured side forces caused by the forced roll were very small but in the dynamic tests, depending on forward speed, …amplitude and frequency of rudder oscillation, large roll motions could be generated resulting in significant changes in the measured side forces. Additional tests with the model fixed relative to a wave are described. With the rudder positioned at four points along the wave, its effectiveness and interaction with the hull are further discussed. Show more

DOI: 10.3233/ISP-1982-2933802

Citation: International Shipbuilding Progress, vol. 29, no. 338, pp. 260-269, 1982

Authors: Flower, J.O.

Article Type: Research Article

Abstract: The more promising wave-power devices utilize resonance or resonance-like phenomena in their operation. Budal and Falnes [1] have brought the theory of such devices to prominence and have proposed an intriguing active-control scheme which seeks to keep the velocity of the primary moving part of the device and the wave-force acting on it in-phase, at least over critical periods in the cycle. The device is held stationary as the wave advances until such a time in the cycle that release of the device at this moment will ensure that it reaches its maximum velocity simultaneously with the peak of the …wave-force. The precise calculation of the time-of-release involves the solution of nonlinear simultaneous equations. Here we present a simple approximate calculation of this time-of-release and suggest an iterative method of improving the accuracy. Show more

DOI: 10.3233/ISP-1982-2933803

Citation: International Shipbuilding Progress, vol. 29, no. 338, pp. 270-275, 1982