SOME QUESTIONS ABOUT GENERAL STRENGTH, PROPULSION AND ENERGY EFFICIENCY OF DEADRISE HULLS

Abstract

Introduction. When a high-speed vessel is moving in the transitional mode loads increase from the interaction of the bottom of the vessel and the waves. Accordingly increase adverse effects health of the passengers and crew. Hull structures and equipment may also be damaged. Modern requirements of classification societies significantly raise the level for permissible accelerations on board high-speed vessels. Various methods are used to reduce shock loads. One of them is an increase of deadrise angle . A decrease in resistance is possible by increasing the relative length of the vessel, which can lead to problems in ensuring general strength. To determine the maximum possible value of the relative length requires knowledge of the relative section modulus. The lack of information about the relative section modulus of an equivalent girder of the vessel occurs during various studies. The choice of the relative length of the vessel is associated with such quality as propulsion and many others. And sometimes, the shipbuilder’s desire to reduce water resistance, by increasing this parameter, is limited by the difficulties of ensuring general strength. In this study, a try will be made to combine the requirements for general strength, propulsion and energy efficiency in order to create new and improve existing ships. Purpose. The goals of this work are to determine: the value of relative section modulus of an equivalent girder for a small vessel, the method for determining the maximum value of the relative length of a small high-speed vessel, the way for reducing the value of the factor EEDI. Results. The value of the relative section modulus of an equivalent girder for a small vessel of transitional mode is defined in this article. Graphic solution of two equations proposed in the article: equation of general strength, taking into account wave acceleration and the equation for the relative section modulus, taking into account the geometry of the hull. The result of this decision is the value of relative section modulus of an equivalent girder for a small vessel of transitional mode. This parameter is required to determine the limiting value of the relative length and finding solutions to reduce the coefficient EEDI. Comparative analysis of the obtained data with the data about strength and weight of the H-girder with length similar to the ship was conducted. The formula for determining the limiting value of the relative length was obtained from the equation of general strength. The way to reduce the energy efficiency factor EEDI, by increasing the relative length, was proposed in this article and demonstrated on the example for a real small high-speed vessel. Conclusions. Improvement of existing technologies may lead to the appearance of new technologies. The software is based on algorithms. The creation of such algorithms is necessary for new programs or for “one digital” assessment of the project, at the beginning of making design decisions. The algorithm proposed in this article can be used to achieve such goals.