Numerical and Experimental Analyses of Transverse Static Stability Loss of Planing Craft Sailing at High Forward Speed

Maneuverability of planing craft is a complicated hydrodynamic subject that needs more studies to comprehend its characteristics. Planing craft drivers follow a common practice for maneuver of the craft that is fundamentally different from ship’s standards. In situ full-scale tests are normally necessary to understand the maneuverability characteristics of planing craft. In this paper, a study has been conducted to illustrate maneuverability characteristics of planing craft by full-scale tests. Accelerating and turning maneuver tests are conducted on two cases at different forward speeds and rudder angles. In each test, dynamic trim, trajectory, speed, roll of the craft are recorded. The tests are performed in planing mode, semi-planing mode, and transition between planing mode to semi-planing mode to study the effects of the craft forward speed and consequently running attitude on the maneuverability. Analysis of the data reveals that the Steady Turning Diameter (STD) of the planing craft may be as large as 40 L, while it rarely goes beyond 5 L for ships. Results also show that a turning maneuver starting at planing mode might end in semi-planing mode. This transition can remarkably improve the performance characteristics of the planing craft’s maneuverability. Therefore, an alternative practice is proposed instead of the classic turning maneuver. In this practice, the craft traveling in the planing mode is transitioned to the semi-planing mode by forward speed reduction first, and then the turning maneuver is executed.

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Development and Optimization of Mathematical Model of High Speed Planing Dynamics

10.5957/fast-2015-043 ◽

2015 ◽

Author(s):

Prin Kanyoo ◽

Dominic J. Taunton ◽

James I. R. Blake

Keyword(s):

Relative Velocity ◽

High Speed ◽

Lift Force ◽

Hydrodynamic Pressure ◽

Physical Nature ◽

Ship Motions ◽

Additional Contribution ◽

Forward Speed ◽

Planing Craft ◽

Hydrostatic Force

The primary difference between a planing craft and a displacement ship is that the predominant force to support the conventional or displacement craft is hydrostatic force or buoyancy. While in the case of planing craft, the buoyancy cedes this role to hydrodynamic lift force caused by flow and pressure characteristics occurring when it is travelling at high forward speed. However, the magnitude of hydrostatic force is still significant that cannot be completely neglected. Due to the high forward speed and trim angle, the flow around and under the planing hull experiences change of momentum and leads to the appearance of lift force according to the 2ndlaw of Newton. In other words, there is a relative velocity between the craft hull and the wave orbital motion that causes hydrodynamic pressure generating hydrodynamic lift force act on the hull surface. Then, in case of behaviors in waves, an additional contribution of ship motions is necessary to be considered in the relative velocity, resulting in nonlinear characteristic of its physical nature.

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Visualization of the Process of Static Buckling of a Micropolar Meshed Cylindrical Panel

10.51130/graphicon-2020-2-4-10 ◽

2020 ◽

pp. short10-1-short10-9

Author(s):

Ekaterina Krylova ◽

Irina Papkova ◽

Vadim Krysko

Keyword(s):

Geometric Nonlinearity ◽

Scale Effects ◽

Stability Loss ◽

Static Stability ◽

Cylindrical Panel ◽

Micropolar Theory ◽

Mesh Structure ◽

Process Visualization ◽

The Mathematical Model ◽

Model Visualization

Process visualization of static stability loss in mechanics is shown by the micropolar meshed cylindrical panel example with two families of mutually perpendicular ribs. The mathematical model of the panel's behavior is based on the Kirchhoff-Love hypotheses. The micropolar theory is applied to ac-count for scale effects. Geometric nonlinearity is taken into account according to the theory of Theodor von Karman. The mesh structure is taken into account based on the Pshenichnov I. G. continuum model. Visualization of numerical results using Autodesk 3ds Max software made it possible to more clearly assess the phenomenon of static buckling of the shell in question. Visualization of the results using 3D made it possible to establish that an in-crease in the distance between the edges of the mesh panel and an increase in the parameter depending on the size does not change the bending shape of the panel, as well as the diagrams of moments and forces at subcritical and supercritical loads.

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Comparisons Between Prediction and Experiment for Lift Force and Heel Moment for a Planing Hull

Journal of Ship Production and Design ◽

10.5957/jspd.2013.29.1.36 ◽

2013 ◽

Vol 29 (01) ◽

pp. 36-46

Author(s):

Carolyn Q. Judge

Keyword(s):

High Speed ◽

Lift Force ◽

Forward Speed ◽

Dynamic Effects ◽

Planing Craft ◽

Underwater Photography ◽

Calm Water ◽

Transverse Stability ◽

The Relationship ◽

Righting Moment

Even in calm water, high-speed vessels can display unstable behaviors such chine walking, sudden large heel, and porpoising. Large heel results from the loss of transverse stability at high forward speed. When a planing craft begins to plane, the hydrodynamic lift forces raise the hull out of the water. The available righting moment resulting from the hydrostatic buoyancy is, therefore, reduced. As the righting moment resulting from hydrostatic buoyancy is reduced, the righting moment resulting from dynamic effects becomes important. These hydrodynamic righting effects are related to the hydrodynamic lift. This article explores the relationship between the hydrostatic lift and righting moment, the hydrodynamic lift and righting moment, and the total lift and heel-restoring moment of a planing craft operating at planing speeds. A series of tow tests using a prismatic hull with a constant deadrise of 20 measured the lift force and righting moment at various angles of heel and at various model velocities. The model was completely constrained in surge, sway, heave, roll, pitch, and yaw. The underwater volume is determined from the known hull configuration and the underwater photography of the keel and chine wetted lengths. The results presented include the total lift and righting moment with the hydrostatic and hydrodynamic contributions for various model speeds at two model displacements.

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Experimental Analyses of Standing Static Stability of Bipedal Robot Equipped with Bi-articular Muscles Function

Journal of the Society of Biomechanisms ◽

10.3951/sobim.41.4_221 ◽

2017 ◽

Vol 41 (4) ◽

pp. 221-229

Author(s):

Toru OSHIMA ◽

Tomohiko FUJIKAWA ◽

Tatsuo MOTOYOSHI ◽

Ken’ichi KOYANAGI

Keyword(s):

Static Stability ◽

Bipedal Robot ◽

Experimental Analyses

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Empirical Methods for Predicting Lift and Heel Moment for a Heeled Planing Hull

Journal of Ship Production and Design ◽

10.5957/jspd.2014.30.4.175 ◽

2014 ◽

Vol 30 (04) ◽

pp. 175-183

Author(s):

Carolyn Q. Judge

Keyword(s):

High Speed ◽

Experimental Program ◽

Naval Academy ◽

Forward Speed ◽

Empirical Methods ◽

Empirical Relationships ◽

Planing Craft ◽

Underwater Photography ◽

Calm Water ◽

Transverse Stability

Even in calm water, high-speed vessels can display unstable behaviors such as chine walking, sudden large heel, and porpoising. Large heel angle can result in the loss of transverse stability at high forward speed. When a planing craft begins to plane, the hydrodynamic lift forces raise the hull out of the water, reducing the underwater geometry. An experimental program at the U.S. Naval Academy has been designed to investigate the transverse stability of planing hulls. An experimental mechanism to force a planing hull model in heave and roll motion was designed and built. The first model tested was a wooden prismatic planing hull model with a constant deadrise of 20, a beam of 1.48 ft (0.45 m), and a total length of 5 ft (1.52 m). The model was held at various heel and running draft positions while fixed in pitch, yaw, and sway. The tests were done at two model speeds, for one model displacement, five fixed heel angles, and five fixed running heave positions. The lift and sway forces, along with the heel moment, were measured and underwater photography was taken of the wetted surface. This article presents a set of equations based on empirical relationships for calculating the lift and heel moment for a prismatic planing hull at nonzero heel angles.

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