NAUI Master Scuba Diver 200 Navigation for Divers that is directly in line with the course you wish to follow. You can then make your way to the object without having to watch the compass continuously. When the object is attained, use the compass to select another object on the heading to be followed. Simply repeat the procedure for as long as you desire to follow the heading. Just be sure the compass needle is properly aligned when you take each sighting. Your compass can assist you in conducting very precise dive patterns. You can swim a square pattern by swimming the first leg on a heading of 0°, the second leg on a heading of 90°, the third leg on a heading of 180°, and the fourth leg on a heading of 270°. An outand back pattern is referred to as a reciprocal course, which is always 180° opposite that of an initial heading. If you swam away from a boat on a heading of 10°, your reciprocal course to return to the boat would be 190°. It is easy to set a reciprocal course on your compass. Just turn until the south end of the needle is between the index marks where the north end was on the outbound leg. A compass can also be used for surface navigation to fix a position when in-line objects are not available. Compass bearings to various terrestrial objects can assist you with the relocation of a dive site, although this type of fix is not as precise as a fix which uses two or more sets of objects which are aligned. Position relocation from a boat using a hand bearing compass can also be quite accurate. Care of your diving compass is required to keep it functioning properly. The instrument should not be dropped, shocked, or abused. Leaving a compass in the sun for prolonged periods can cause the liquid inside to expand and a leak can result. The instrument should be rinsed after use, as sand and grit can jam the bezel. The bezel should turn freely, but should hold a setting. Do not place or store your compass near magnetic items or magnetic fields, including electric lines or cables. COMBINING NAVIGATIONAL TECHNIQUES Both natural navigation and compass position fixing techniques are used to locate a dive site. If swimming from shore, you may swim along a course indicated by a set of in-line objects (such a course is called a range), or along a reciprocal course indicated by a compass bearing from an object on shore. This heading is maintained until the course intersects another line of direction that fixes the desired position. In such cases, the compass heading is selected and set prior to descent. The heading frequently uses the shoreline as a reference so you will know if you are swimming toward or away from shore once you are on the bottom. Upon reaching the bottom, landmarks are noted to indicate your point of departure, especially if you intend to return to that point at the end of the dive. Other natural aids to navigation are noted. Turn yourself to align your centerline with the starting bearing of the compass and take a sighting on a distant object on the course you wish to follow, then move in that direction. Distance is estimated and your heading is changed as is appropriate to maintain your planned dive pattern. Natural aids to navigation—depth, shadows, water movement, etc.—are noted all along the way. Frequent reference to your compass and depth gauge allow you to navigate more accurately than by the use of natural aids only. You take pride in returning to your exact starting point at the end of a dive without surfacing. Your combined navigational skills have made your dive easier and FIGURE 7-9. NAVIGATING UNDERWATER WITH A CONSOLE-MOUNTED COMPASS
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