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NAUI Master Scuba Diver 198 Navigation for Divers Rectangular Triangular slowly but steadily for 35 bar (500 psi) parallel to the sand ripples on the bottom. You then agree to make a 90° turn toward shallower water on the right and are aided by the sand ripples on the bottom. With the sun in your face, you move into 12 m (40 ft) of water during the next 35 bar (500 psi), then agree to another 90° turn to the right. You again parallel the sand ripples on the bottom, and the sun is on your left. After another 35 bar (500 psi), you and your buddy agree to your final right-hand turn. The sun is now to your back, and you are swimming perpendicular to the sand ripples. As you approach a cylinder pressure of about 35 bar (500 psi), and a depth of 15 m (50 ft), the anchorline of the boat comes into view and you begin your ascent. Strict adherence to a dive pattern is not essential for effective navigation (figure 7-6). Temporary deviations from a heading to investigate points of interest are acceptable as long as the general direction is maintained and some pace of forward progress is maintained or the distance is measured. Another form of natural navigation can be used to identify a position at the surface. A position can be determined from the observations of terrestrial objects. When the direction and distance to two or more landbased objects is known, the resulting position is known as a fix (figure 7-7). Direction is established by natural means through the selection of objects that align with one another, such as a phone pole that is in line with the edge of a house. Two such sets of in-line objects result in a very precise fix. The angle between the two directions should ideally be 90° and should never be in or near a straight line (close to 180°). Notes and simple drawings of a fix should be made. Reciprocal 180�� 90�� 120�� Start/Finish Start/Finish Start/Finish FIGURE 7-5. TYPICAL DIVE PATTERNS FIGURE 7-6. NATURAL NAVIGATION/GENERAL DIVE COURSE


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