Experimental Determination of the Added Inertia and Damping of a 30 Degree Deadrise Planing Boat in Roll PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages : 38
Book Description
This is the fourth of four reports on research designed to obtain basic hydrodynamic information about planing hulls through the use of captive models tests. The information is to be used for the general study of dynamic stability while underway, course keeping, turning and maneuvering, etc. The models tested were of idealized patrol boats having an LBP of 100 ft., a beam of 20 ft., and a displacement of 100 long tons. The models had prismatic hull forms with 10, 20, and 30 degrees of deadrise. The report presents the results of free oscillation tests on an unappended prismatic hull with 30 degrees of deadrise. The tests were conducted at a beam loading coefficient of 0.4375, at three speeds Cv = 1.5, 3.0, and 4.0, three trim angles 0, 3, AND 6 DEGREES, and at yaw angles of 0,10, and 15 degrees. Roll extinction records were taken with four different spring stiffnesses, first at rest in air and then underway in water, at each test condition. The roll period and logarithmic decrement were determined from these records and tabulated. The added mass moment of inertia and damping in roll were deduced from these data assuming a linear damped harmonic oscillator. Empirical expressions for the inertia and damping are presented and compared with the data. These expressions are used to predict the rolling characteristics of a prototype 100 ft. boat.
Author: Publisher: ISBN: Category : Languages : en Pages : 38
Book Description
This is the fourth of four reports on research designed to obtain basic hydrodynamic information about planing hulls through the use of captive models tests. The information is to be used for the general study of dynamic stability while underway, course keeping, turning and maneuvering, etc. The models tested were of idealized patrol boats having an LBP of 100 ft., a beam of 20 ft., and a displacement of 100 long tons. The models had prismatic hull forms with 10, 20, and 30 degrees of deadrise. The report presents the results of free oscillation tests on an unappended prismatic hull with 30 degrees of deadrise. The tests were conducted at a beam loading coefficient of 0.4375, at three speeds Cv = 1.5, 3.0, and 4.0, three trim angles 0, 3, AND 6 DEGREES, and at yaw angles of 0,10, and 15 degrees. Roll extinction records were taken with four different spring stiffnesses, first at rest in air and then underway in water, at each test condition. The roll period and logarithmic decrement were determined from these records and tabulated. The added mass moment of inertia and damping in roll were deduced from these data assuming a linear damped harmonic oscillator. Empirical expressions for the inertia and damping are presented and compared with the data. These expressions are used to predict the rolling characteristics of a prototype 100 ft. boat.
Author: Publisher: ISBN: Category : Languages : en Pages : 38
Book Description
This is the fourth of four reports on research designed to obtain basic hydrodynamic information about planing hulls through the use of captive models tests. The information is to be used for the general study of dynamic stability while underway, course keeping, turning and maneuvering, etc. The models tested were of idealized patrol boats having an LBP of 100 ft., a beam of 20 ft., and a displacement of 100 long tons. The models had prismatic hull forms with 10, 20, and 30 degrees of deadrise. The report presents the results of free oscillation tests on an unappended prismatic hull with 30 degrees of deadrise. The tests were conducted at a beam loading coefficient of 0.4375, at three speeds Cv = 1.5, 3.0, and 4.0, three trim angles 0, 3, AND 6 DEGREES, and at yaw angles of 0,10, and 15 degrees. Roll extinction records were taken with four different spring stiffnesses, first at rest in air and then underway in water, at each test condition. The roll period and logarithmic decrement were determined from these records and tabulated. The added mass moment of inertia and damping in roll were deduced from these data assuming a linear damped harmonic oscillator. Empirical expressions for the inertia and damping are presented and compared with the data. These expressions are used to predict the rolling characteristics of a prototype 100 ft. boat.
Author: Edward M Lewandowski Publisher: World Scientific ISBN: 9814490067 Category : Technology & Engineering Languages : en Pages : 424
Book Description
This book presents a theoretical treatment, as well as a summary of practical methods of computation, of the forces and moments that act on marine craft. Its aim is to provide the tools necessary for the prediction or simulation of craft motions in calm water and in waves. In addition to developing the required equations, the author gives relations that permit at least approximate evaluation of the coefficients so that useful results can be obtained. The approach begins with the equations of motion for rigid bodies, relative to fixed- and moving-coordinate systems; then, the hydrodynamic forces are examined, starting with hydrostatics and progressing to the forces on a moving vehicle in calm water and (after a review of water-wave theory) in waves. Several detailed examples are presented, including calculations of hydrostatics, horizontal- and vertical-plane directional stability, and wave-induced motions. Also included are unique discussions on various effects, such as fin-hull interactions, numerical stability of integrators, heavy torpedoes, and the dynamics of high-speed craft. The book is intended to be an introductory-level graduate text and a reference for the practicing professional.
Author: Edward M. Lewandowski Publisher: World Scientific ISBN: 9789810247560 Category : Technology & Engineering Languages : en Pages : 428
Book Description
This book presents a theoretical treatment, as well as a summary of practical methods of computation, of the forces and moments that act on marine craft. Its aim is to provide the tools necessary for the prediction or simulation of craft motions in calm water and in waves. In addition to developing the required equations, the author gives relations that permit at least approximate evaluation of the coefficients so that useful results can be obtained. The approach begins with the equations of motion for rigid bodies, relative to fixed- and moving-coordinate systems; then, the hydrodynamic forces are examined, starting with hydrostatics and progressing to the forces on a moving vehicle in calm water and (after a review of water-wave theory) in waves. Several detailed examples are presented, including calculations of hydrostatics, horizontal- and vertical-plane directional stability, and wave-induced motions. Also included are unique discussions on various effects, such as fin-hull interactions, numerical stability of integrators, heavy torpedoes, and the dynamics of high-speed craft. The book is intended to be an introductory-level graduate text and a reference for the practicing professional.