![]() ![]() While the gyres are surface currents, there are other equally important countervailing deep currents. Three gyres in the Southern Hemisphere circle the South Atlantic, the South Pacific and the Indian Ocean in a counterclockwise direction. ![]() There are two gyres in the Northern Hemisphere that travels in a clockwise direction: one circling the North Atlantic the other, the North Pacific. The largest currents are part of the world’s five gyres- giant circular oceanic currents. In addition, ocean currents are affected by variations in water density resulting from different levels of salinity and temperatures. Ocean, lake and river currents respond to the push of prevailing winds. Currents are also found in open water where they range from huge, persistent ocean movements, such as the Gulf Stream or the California Current, to the strong but short-lived undertow, or rip current, of a beach where surf finds its way back offshore. Lake Erie and Delaware Bay, for example, are two bodies of water renowned for choppy conditions.īoth coastal and inland boaters are familiar with currents, the horizontal flow of water in a downstream direction. Over long fetches of shallow water, strong winds may create waves of moderate height, but with a viciously steep and short chop- which is even more dangerous than ocean waves of greater size. The same sea, meeting a current, will rear up, creating a rip, sometimes amplified by the narrowing funnel of an inlet. When this heavy sea encounters shallow water, its energy can no longer be absorbed by the circular movement of water within each wave. Increasing wind tears at the wave tops, revealing whitecaps and throwing off spume. #Reduce speed and head into the waves at 45 degree angle freeThe ripples gradually build into waves.Īs the waves travel quickly over a long fetch, the distance free of obstructions, each crest reaches higher above its trough. The surface of a swell may be perfectly calm, but it is usually textured by the wind into groups of tiny ripples called "catspaws". Large ocean undulations, generated by distant storms and unrelated to local causes, are called swells. This becomes most apparent while running at low speed in close quarters. Skippers of both will find one of them a major factor affecting the boat’s maneuverability. Neither a displacement nor planing boat can ignore the wind current. On the other hand, given the same conditions, a planing - type hull with a high tuna tower could be more affected by wind than by current. Water is much denser than air, so a half-knot cross current may have more effect on a displacement cruiser than a stiff 15 to 20 knot wind. Displacement-type hulls with considerable draft are affected by current to a greater extent than shallower-draft, lighter, planing-type hulls. Hull type has the most effect on how a boat reacts to the current. This will help you maintain control, and avoid falling off of a wave, or having a wave break over your stern. So, in general, when operating a boat in large waves and high winds, head into the waves at a slight angle, and reduce your speed. Since bows on many power boats are higher than the sterns, they tend to fall off the wind when backing, despite anything that is done with the helm. ![]() Keeping a course or maneuvering in close quarters may be straightforward on a calm day during a slack tidal current, but the boat may become quite ill-mannered when coping with a stiff crosswind or crosscurrent. Boat Owners Association of The United StatesĪ boat’s handling characteristics are affected by wind and current, no matter what type of hull and power combination it has. ![]()
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