International Shipbuilding Progress - Volume 48, issue 2

Authors: Wind, H.G. | Rotgers, A.

Article Type: Research Article

Abstract: In this paper a concept is studied, where the energy for the propulsion of a ship is extracted from the down flow of the river. In this concept three elements are important; a wire which is connected upstream, paddles on both sides of the ship and a drum which rotates due to the movement of the paddles Due to the rotation of the paddles, the drum winds up the wire and pulls the ship upstream A theoretical framework is developed …and verified in flume. The conclusion is that the concept indeed is feasible. For the experimental configuration the velocity of the vessel relative to a fixed observer is about 20%–25% of the flow velocity of the river. Show more

Citation: International Shipbuilding Progress, vol. 48, no. 2, pp. 91-101, 2001

Authors: Pasqualino, I.P. | Estefen, S.F. | Netto, F.A.

Article Type: Research Article

Abstract: Ultimate strength of structural flat panels typical of ships' structures is analysed. Finite element models have been used to consider geometric and material non-linear behaviour based on thin shell and plasticity flow theories. The effects of initial geometric imperfections, boundary conditions and applied loads on the structural capacity of a stiffened panel are investigated. Results from buckling analyses are compared with design recommendations.

Citation: International Shipbuilding Progress, vol. 48, no. 2, pp. 103-116, 2001

Authors: Dejhalla, R. | Mrša, Z. | Vuković, S.

Article Type: Research Article

Abstract: A computational method developed for solving the minimum ship wave resistance problem is presented in the paper. The method involves coupling ideas from two distinct research fields: numerical ship hydrodynamics and genetic algorithms. To approach the minimum ship wave resistance problem numerically, the genetic algorithm is coupled with a numerical method for solving the three-dimensional potential flow past a ship moving at constant speed in calm water. The numerical method is based upon a well known …Dawson's method. The developed optimization procedure is demonstrated by selecting the Series 60 (C_B =0.60) hull as mother-model for the development of the optimal ship hull forms. The numerical results of optimization procedure indicate that the optimized hull forms yield a reduction in wave resistance. Show more

Citation: International Shipbuilding Progress, vol. 48, no. 2, pp. 117-133, 2001

Authors: Millward, A. | Askew, K.M. | Whattam, P.

Article Type: Research Article

Abstract: An investigation has been made to measure the variation of the actual or running wetted surface area (RWSA) of a round bilge light displacement monohull and a catamaran for different separation ratios to determine the effect on the calculation of the resistance component of the total resistance and hence on the predicted power requirement of a full scale vessel. The results of the investigation showed that the RWSA for this type of round bilge …light displacement hull was larger than the static wetted surface area (SWSA) for the monohull by up to 10% for a Froude number of 1.0 and as much as 20% for a Froude number of 1.2. The change in the proportion of frictional resistance to residuary resistance was shown to reduce the estimated power requirement for a sample 25m vessel by approximately 10%. No systematic variation of the RWSA with hull separation (S/L) was found for the catamaran configuration, except for the narrowest separation (S/L =0.2) over the Froude number range 0.6 < F_n < 0.7, so that the variation of RWSA was found to be essentially the same as for the monohull. Consequently the interference factor between the hulls was only found to be affected at the higher Froude numbers. Show more

Citation: International Shipbuilding Progress, vol. 48, no. 2, pp. 135-148, 2001

Authors: Prpić, Jasna | Nabergoj, Radoslav

Article Type: Research Article

Abstract: A numerical approach for predicting motion and tension of marine cables during laying operations in a rough sea is presented. The solution methodology consists of dividing the cable into straight elements, which must satisfy equilibrium equation and compatibility relations. The system of obtained nonlinear differential equations is solved by Runge-Kutta method, taking explicitly into account the effect of regular and/or irregular waves. Illustrative applications of the method are given for a cable-lying …ship of approximately 100 m length, designed to install and repair submarine cable systems. The results are presented as transfer function and response spectrum of cable dynamic tension for two different types of cable, several ship velocity-heading combinations. The obtained responses make it possible to determine order statistics of the cable lying process. Show more

Citation: International Shipbuilding Progress, vol. 48, no. 2, pp. 149-167, 2001

Authors: Santos, T.A. | Soares, C. Guedes

Article Type: Research Article

Abstract: This work presents a formulation to calculate the time change of the damage stability of ships with open water. It adopts a pressure integration technique, which has been used earlier to calculate the hydrostatic properties of marine structures, and is extended here to compute the rates of flow through damage openings while performing flooding simulations. The principles of this technique are exposed and its advantages and disadvantages are discussed. Using a practical method to generate the …panels required to use the pressure integration technique, a damaged Ro-Ro ship numerical model has been generated. Results of its intact and damaged stability, obtained using the pressure integration technique, are presented, compared with other numerical results and discussed. The technique is then applied to estimate the rate of flow through damage openings on the ship's hull. The results allow the conclusion that this technique can be successfully applied to the time domain simulation of ship flooding, both to compute the damaged ship hydrostatic properties and the rate of flow through the damage openings on the ship's hull. Show more

Citation: International Shipbuilding Progress, vol. 48, no. 2, pp. 169-188, 2001