OutdoorNebraska

21 Chapter 3 ■ Bridges ◆ Most states have laws requiring that you pass under bridges at a slow speed. You should always reduce your speed and proceed with caution near any bridge or man-made structure that decreases visibility and passage. ◆ Many bridges are high enough to allow normal boat passage. However, some bridges provide only low clearance during normal conditions or periods of high water. ◆ Many drawbridges open and close when a boat arrives. To request passage, contact the bridge operator using sound signals or a VHF marine radio. ◆ Be aware that debris can collect around pilings of bridges and create dangerous obstructions. Changing Water Levels Fluctuating water levels can cause special hazards for boaters. Water levels can change rapidly due to tides, flooding rivers, or water released through dams. Any of these conditions can cause boats to run aground in areas where navigation may have been safe earlier. Any change in water level also can affect docking to a fixed pier. Tides on Coastal Waters ◆ Tides are created by the sun and moon exerting a pull on the earth. High tides and low tides are predictable, and each one normally occurs twice daily at approximately six-hour intervals. ◆ Boat operators in coastal waters need to be mindful of the effect of tides. The rise and fall of tides can cause water levels to fluctuate by several feet and also can generate strong currents. Some tidal currents are strong enough that some boats cannot make headway against the current. ◆ As a boat operator, you need knowledge of the tides in your boating area. It is a good idea to learn how to read the tide tables found in many newspapers in coastal areas. Tide schedules also can be found on weather radio channels. Compasses and Charts A good compass and chart are always useful. Having a compass and knowing how to use it are invaluable when darkness, fog, or a storm occurs. Therefore, it's a good idea to take a basic course in navigation, usually available from the U.S. Coast Guard Auxiliary, U.S. Power Squadrons, American Sailing Association, and others. Steering Compass ◆ A compass, which is used to assist in navigation, is an instrument that shows magnetic north. You must apply a correction to determine the direction of true north. The ability to steer a boat by a compass is useful if land is out of sight, visibility is reduced, or the boat operator is disoriented. ◆ Mount a boat compass away from iron, magnets, and electrical wiring and equipment. Practice with your compass and other navigation equipment in good weather. Make sure you know how to use them. This will give you confi- dence during bad weather. Nautical Charts ◆ Charts contain important information such as water depths and the locations of channels, sand bars, rocks, and vegetation. This is especially helpful when boating in bays or in large lakes. They also can be used to determine the most direct course possible for fuel conservation. ◆ Check with the local marina for charts. If none are available, obtain local knowledge before boating in an unfamiliar area. chart Map used for navigation Sailboat operators should always check clearance of the boat's mast before passing under bridges. This can be very difficult to determine from the operator's position on the boat. On charted waters, the chart will indicate bridge clearance at a particular water level. Current water level and tide must be factored in to determine present clearance. A boat's compass can be invaluable in bad weather and at night. Make sure you know how to use it. Copyright © 2014 Boat Ed, www.boat-ed.com

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