About: Beam (nautical) is a research topic. Over the lifetime, 1113 publications have been published within this topic receiving 4771 citations. The topic is also known as: BOA.
Papers published on a yearly basis
TL;DR: Estimates of the ship beam and its velocity are dealt with by processing SAR images of the Kelvin and turbulent wakes by employing a novel method that exploits the expansion of the turbulent wake aft a ship.
Abstract: Synthetic aperture radar (SAR) images of ships and their wakes frequently exhibit long dark and bright streaks. Some of them can be attributed to the Kelvin wavewake and others to the turbulent and bright narrow V-wake. The wakes contain information about the ship. The present work deals with estimates of the ship beam and its velocity by processing SAR images of the Kelvin and turbulent wakes. It is assumed that the ship moves along a straight path with constant speed. For the detection of the linear features of the ship wake, the fast discrete Radon transform is employed. Once the turbulent wake is detected, the ship beam is estimated by a novel method that exploits the expansion of the turbulent wake aft a ship. A semiempirical relation between the ship beam and the width of its turbulent wake is derived and analyzed. An algorithm for estimating the width of the turbulent wake in SAR images and the ship beam is developed. The spectrum of ship-generated waves along the Kelvin cusp-lines is discussed. Processing of the lines, pertaining to the Kelvin wake bounds, and analysis of the spectral peaks enables to estimate the ship speed. Numerical examples of processing of airborne SAR images are provided.
TL;DR: In this paper, a review of the mechanics of ship capsize under steady and transient conditions is reviewed, focusing on recent applications of global geometrical techniques of nonlinear dynamics.
Abstract: The mechanics of ship capsize under steady and transient conditions is reviewed, focusing on recent applications of global geometrical techniques of nonlinear dynamics. These yield significant new ideas about capsize in waves and its generalization, the escape of a driven oscillator from a potential well. These ideas are robust against gross changes in the forms of the stiffness and damping functions. Fractal basin boundaries in phase and control space yield useful design criteria against transient capsize, which have been applied to real ships. Invariant manifolds are used to explain and predict the sudden loss of safe basin in the space of the starting conditions, and indeterminate resonant jumps to capsize. Further work is concerned with capsize suppression by heave-roll coupling; effects of parametric excitation; and capsize under a propagating wave front. After this historical review, the practical relevance of the results is assessed, and suggestions are made for a standardized transient testing procedure for hulls. A systematic formulation for rolling in beam waves, employing the effective gravitational field perpendicular to the wave surface and the Froude-Krilov assumption, allows the use of the calm-water GZ curve. With general stiffness and damping functions, dimensional analysis offers insights that are often overlooked: for example, the sustainable wave slope is always proportional to the angle of vanishing stability. A degree of quantification is provided by a design formula derived from the displacement magnification of linear resonance. This is validated by Melnikov theory and simulation. It predicts that under worst-case excitation we have: sustainable wave slope = 2 ζθv , where θv is the angle of vanishing stability and ζ is a damping ratio appropriate for heavy roll. So in ocean waves of slope 0.5 (≈30°), a vessel with a θv of one radian needs a damping ratio of about 1/4. Implications for the design of hulls reveal counter-intuitive results: it is the distance of the potential barrier, not its height, that prevents escape or capsize. The formula helps to define a universal capsize diagram. New results on symmetry breaking are finally presented. These show that capsize studies of a symmetric unbiased vessel can give seriously unsafe results. The sustainable wave slope is so sensitive to a symmetry-breaking bias (due to wind or cargo imbalance) that a static heel of 2.5° can halve the sustainable slope over a wide range of sea states. This review article has 112 references.
TL;DR: In this paper, the stiffness and damping characteristics of the journal bearings' oil film, ship hull and bearings frame should be taken into account, and the presented numerical analysis method is compared and verified by measurements on real ships.
Abstract: Proper shaft line alignment is one of the most important actions during the design of the propulsion system. Usually, a beam model of the power transmission system is isolated from the ship hull. Therefore, determining the correctness of the boundary conditions is one of the most important and difficult issue during the marine shaft line alignment calculations. In the author's opinion stiffness and damping characteristics of the journal bearings’ oil film, ship hull and bearings frame should be taken into account. Ship hull deformations, under different load conditions and regular sea waves, are also analysed. The presented numerical analysis method is compared and verified by measurements on real ships.
TL;DR: In this article, a dynamic model of a ship-mounted container crane (called the "mobile harbor") subject to the motions of ship itself imparted by random sea waves is investigated, and the condition of the sea is assumed to be State 3.
Abstract: In this paper, a dynamic model of a ship-mounted container crane (called the “mobile harbor”) subject to the motions of ship itself imparted by random sea waves is investigated. The condition of the sea is assumed to be State 3. The ship's heaving, pitching and rolling motions are considered as the main motions in exciting the mounted crane. Equations of motion are derived using the Lagrange method. Simulation results reveal that the lateral sway angle of the load becomes the biggest in the beam sea, whereas the pitching motion of the ship in the heading sea is the biggest. As a conclusion, the operation of mobile harbors in the heading sea is recommended. The developed mathematical model has been validated by experiments.
TL;DR: In this article, a procedure to calculate horizontal slow drift excitation forces on an infinitely long horizontal cylinder in irregular beam sea waves is presented, where the hydrodynamic boundary value problem is solved correctly to second order in wave amplitude.
Abstract: A procedure to calculate horizontal slow drift excitation forces on an infinitely long horizontal cylinder in irregular beam sea waves is presented. The hydrodynamic boundary-value problem is solved correctly to second order in wave amplitude. Results in the form of second order transfer functions are presented for different two-dimensional shapes. It is concluded that Newman's approximative method is a practical way to calculate slow drift excitation forces on a ship in beam sea and suggested that it may be used in a more general case. Applications of the results for moored ships are discussed.