Second-order steady drift of a floating triangular platform : theory and experiment

• Main Author: Dunphy, Patricia
• Other Authors: Memorial University of Newfoundland. Faculty of Engineering and Applied Science
• Format: Thesis
• Language: English
• Published: 1989
• Subjects: Ocean waves > Mathematical models; Offshore structures > Hydrodynamics; Newfoundland studies; University of Newfoundland
• Online Access: http://collections.mun.ca/cdm/ref/collection/theses2/id/232976

Thesis (M.Eng.)--Memorial University of Newfoundland, 1989. Engineering and Applied Science Bibliography: leaves 94-98. As ocean industries have grown to demand larger offshore vessels achieving ever increasing levels of performance, the need for a better understanding of the phenomena which govern motions and loading of these structures has been recognized. These motions and forces are a result of complex environmental conditions including ice, wind, current and waves. A significant part of the environmental loading is due to waves. -- In general wave loading on a structure is a complex non-linear process of which the first- and second-order (in wave amplitude) components are of main interest. The steady second-order component of drift force may cause large excursions of the structure and therefore must be seriously considered in the design considerations of mooring and dynamic positioning systems. -- In this thesis second-order mean drift forces on a triangular floating structure in regular waves are calculated utilizing far field potential theory. These computed forces are compared to those measured during testing of a 1:200 scale model of a moored triangular body. This is done in an attempt to decide whether mooring forces can be reasonably estimated for such a structure. -- It was concluded that the mean drift forces can be reasonably well predicted using the method presented. Therefore this method can be used as an aid in the design process.