THE ENVIRONMENTWind and CurrentA boats handling characteristics are effected by wind and current, no matter what type of hull and power combination it has. 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. Since bows on many power boats are higher than the terns, they tend to fall off the wind when backing, despite anything that is done with the helm. |
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| Hull type has the most effect on how a boat reacts to the current. Displacement-type hulls with considerable draft are affected by current to a greater extent than shallower-draft, lighter, planing-type hulls. Water is much denser than air, so a half-knot crosscurrent may have more effect on a displacement cruiser than a stiff 15-to 20- knot wind. 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. Neither a displacement nor planing boat can ignore the wind current. Skipper of both will find one of them a major factor affecting the boats maneuverability. This becomes most apparent while running at low speed in close quarters. | ||||||||||||||||||||||||||||||
Tides and Sea Conditions |
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| Large ocean undulations, generated by distant storms and unrelated to local causes, are called swells. The surface of a swell may be perfectly calm, but it is usually textured by the wind into groups of tiny ripples called catspaws. The ripples gradually build into waves. Each crest reaches higher above its trough as the waves travel faster over a longer fetch-the distance free of obstructions. Increasing wind tears at the wave tops, revealing whitecaps and throwing off spume. When this heavy sea encounters shallow water, its energy can no longer be absorbed by circular movement of water within each wave. The crests rise and break. Surf crashes ashore. | ||||||||||||||||||||||||||||||
| The same sea, meeting a current will rear up, creating a rip, sometimes amplified by the narrowing funnel of an inlet. Over long fetches of shallow water strong winds may create waves of moderate height, but viciously steep and short a chop-even more dangerous than ocean waves of greater size. Lake Erie and Delaware Bay, for example, are two bodies of water renowned for choppy conditions. | ||||||||||||||||||||||||||||||
| Coastal and inland boaters are familiar with currents, the horizontal flow of water in a downstream direction. 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. Ocean, lake and river currents respond to the push of prevailing winds. In addition, ocean currents are affected by variations in water density resulting from different levels of salinity and temperatures. | ||||||||||||||||||||||||||||||
| The largest currents are part of the worlds five gyres- giant circular oceanic currents. There are two gyres in the Northern Hemisphere that travels in a clockwise direction: one circling the North Atlantic; the other, the North Pacific. Three gyres in the Southern Hemisphere circle the South Atlantic, the South Pacific and the Indian Ocean in a counterclockwise direction. While the gyres are surface currents, there are other equally important countervailing deep currents. | ||||||||||||||||||||||||||||||
| Regular, intermittent currents that respond to movement of the sun and moon are called tidal currents. Tides are the actual rise and fall in local water level as tidal currents force masses of water alternately against and away from shore. Incoming tidal currents flood, then ebb as they retreat. The strongest are associated with spring tides during new and full moons, when the moon and sun pull in parallel directions. Tide currents flow more gently as neap tides that occur at the quarter moon. | ||||||||||||||||||||||||||||||
| Every current, regardless of its origin, has a set and a drift (speed). Set is the true direction toward which a current flows; drift is its speed. The speed of tidal currents and the height of the tides are so important to coastal navigation that annual tide tables and tidal current tables are published under government supervision. | ||||||||||||||||||||||||||||||
| Depending upon the bodies of water on which you boat, tides can have a major impact on your boating experience. Watch the tide charts or listen to tide reports in your area before you go boating. Going aground is never a good time. | ||||||||||||||||||||||||||||||
Boating and the Environment |
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| Boat owners who do their own maintenance and repair work must be aware of the environmental consequences, and must learn the basic steps they can take to protect the environment, remembering that they themselves are part of what they will be protecting. If they prefer to use professional maintenance, they should apply the same basic principles to the yard that is doing the work. | ||||||||||||||||||||||||||||||
10 ways to more environmentally safe boating |
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| Boaters have a vested interest in clean water, which is able to support diverse fish and wildlife. One by one our collective actions add up. Here are some ideas from the BOAT/US Clean Water Trust about how you can help the waters while boating. | ||||||||||||||||||||||||||||||
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Marine Sanitation Devices (MSDs) |
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| In most inland and coastal waters, boats with installed toilets are required to have a sanitation system on board in order to control pollution. Standards have been set by the Environmental Protection Agency, and regulations have been Issued by the Coast Guard, covering the certification and use of Marine Sanitation Devices. Sanitation systems consist of an installed head (toilet), a waste-treating device (MSD), and/or a holding tank. | ||||||||||||||||||||||||||||||
| As with most Coast Guard Certified equipment, there are different classifications to cover most every marine application. | ||||||||||||||||||||||||||||||
| Type One MSD systems, such as a head coupled with a Lectra-San, are legal on vessels less than 65 feet that boat in an area not declared a Federal No-Discharge Zone. Type One MSDs typically discharge treated waste directly overboard. Type One MSDs are treatment systems that reduce bacteria and discharge no visible floating solids. (Not legal in some state boating areas as well. Check local laws before installing.) | ||||||||||||||||||||||||||||||
| Type Two MSD systems are similar to type one systems, but are more powerful, and do a better job of treating waste. These are typically installed in boats over 65 feet because of the power demands, but can be used on any vessel outside of a no-discharge zone. | ||||||||||||||||||||||||||||||
| Type Three MSD systems are the most prevalent system in use today, as they are the least complicated and the least expensive. This system used a head connected directly to a holding tank. Some systems use "Y-valves" that allow waste flow to be diverted directly overboard. (outside 3-mile discharge limit) Holding tanks can be emptied at many marinas or state run pump-out stations. | ||||||||||||||||||||||||||||||
| Portable toilets are usually small units (Porta-Potties) that are "charged" with a few gallons of water and special chemicals. This treated water, plus the wastes, are flushed into the bottom each time the unit is used. The toilet can be used for several days before pumpout is needed. Though these are not considered to be MSDs as they are not permanently installed, they are legal to use on all waters. | ||||||||||||||||||||||||||||||
Sewage System OptionsOptions for your boat's sewage system, depending on where you boat: |
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*States with lakes capable of interstate navigation may allow the use of Type I or II's. |
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Are You In Compliance? |
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