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NAUI Master Scuba Diver 202 Navigation for Divers Desired Course Bearing Bearing Actual Course meridian. Such lines of latitude and longitude appear on charts and are used to establish position as well as to provide an accurate scale for distances on a chart. The interpretation of charts and the proper use of them requires training. Such training is readily available through Power Squadron and other boating courses. These courses are inexpensive and recommended. The navigational techniques learned are applicable to diving navigation. ADVANCED UNDERWATER NAVIGATIONAL EQUIPMENT Among the most sophisticated equipment for underwater navigation are acoustic beacons and receivers. These are small, battery-operated devices that transmit and receive a high frequency signal when activated. A diver who is equipped with a receiver determines the direction of the beacon by slowly rotating in the water until the receiver produces an audible tone in a headset. A compass bearing (the angular direction to an object expressed in terms of compass degrees from north, e.g., a bearing of 270°) is then noted and the diver swims toward the beacon until it is visually located. These types of “pingers” are often used by scientists or commercial divers to mark expensive instruments or structures under water, in order to relocate them. There are new sophisticated personal homing and navigation systems available for recreational divers. These systems make it easy to relocate a boat, another diver, or any underwater location that is marked. One system has a reported range of 600 m (2000 ft). More advanced systems incorporate communication, sonar navigation, mapping, and data recording capabilities into one package. Global Positioning System (GPS) devices enable boats to move to surface locations with errors of less than 50 m (165 ft). SUMMARY Diving navigation is more than just taking a bearing and swimming. Advanced divers know how to organize and execute a dive knowing their approximate location at all times, using natural and compass navigational aids. A compass is one of the diver’s most valuable tools, and it is important to learn to use it correctly. This chapter described some of the features and methods of using a compass under water. Only by continued practice while diving will most divers become competent and proficient navigators. Desired Course Actual Course Compensate by swimming at an angle into the current Uncompensated Compensated FIGRUE 7-10. COMPENSATING FOR LEEWAY FOR FURTHER READING Blount, S. Treasure Hunting with a Metal Detector, In, Around, and Underwater. Pisces Books. Desert Star Systems. Advanced Navigation Equipment. www.desertstar.com. Gray, L. How to Navigate Today. Cornell Maritime Press, Best Publishing. Joiner, J. NOAA Diving Manual: Diving for Science and Technology. 4th Edition. Best Publishing, 2001. Keatts, H.C. Guide to Shipwreck Diving, New York and New Jersey. Pisces Books, 1992.


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