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This motion is generated directly either by the water and wind motion, particularly lateral wave motion, exerting forces against the hull or by the ship's own propulsion; or indirectly by the inertia of the ship while turning. This movement can be compared to the vessel's lateral drift from its course.
Consider a boat moving from right to left with constant speed v, emitting waves of varying wavelength, and thus wavenumber k and phase velocity c(k), of interest when < v for a shock wave (cf., e.g., Sonic boom or Cherenkov radiation). Equivalently, and more intuitively, fix the position of the boat and have the water flow in the opposite ...
Ocean surface currents Distinctive white lines trace the flow of surface currents around the world. Visualization showing global ocean currents from January 1, 2010, to December 31, 2012, at sea level, then at 2,000 m (6,600 ft) below sea level Animation of circulation around ice shelves of Antarctica
If a vessel runs directly against a current or directly with a current, the speed of the vessel and speed of the current can be added or subtracted from each other. Such as, a vessel has a speed of 8 knots through the water and the vessel is traveling with the current, which is at 2 knots, then the speed over ground is 8+2 and the vessel's true ...
Hull speed or displacement speed is the speed at which the wavelength of a vessel's bow wave is equal to the waterline length of the vessel. As boat speed increases from rest, the wavelength of the bow wave increases, and usually its crest-to-trough dimension (height) increases as well. When hull speed is exceeded, a vessel in displacement mode ...
The speed of the craft at a given point of sail contributes to the "apparent wind"—the wind speed and direction as measured on the moving craft. The apparent wind on the sail creates a total aerodynamic force, which may be resolved into drag —the force component in the direction of the apparent wind—and lift —the force component normal ...
The squat effect is the hydrodynamic phenomenon by which a vessel moving through shallow water creates an area of reduced pressure that causes the ship to increase its draft (alternatively decrease the underkeel clearance of the vessel in marine terms) and thereby be closer to the seabed than would otherwise be expected.
The legs of water beetles have little hairs which spread out to catch and move water back in the power stroke, but lay flat as the appendage moves forward in the return stroke. Also, one side of a water beetle leg is wider than the others and is held perpendicular to the motion when pushing backward, but the leg rotates when the limb returns ...