How to Adjust Ritchie Magnetic Compass
- 1). Mount the compass in its intended location in the boat, but do not permanently secure it. It may be necessary to rotate it during the adjustment process. Make sure any metal objects near the compass are secure in their normal, seagoing position. Note the two compensating magnet adjustment rods on the compass. (On some models, black plastic caps must be removed to gain access to the adjusting rods.) The slots on these adjusting rods should be in their horizontal or neutral position.
- 2). Identify two sets of landmarks on the chart: one set aligned as closely as possible (within 10 degrees) of a magnetic north and south line, the other aligned east and west. These work best if the boat can be maneuvered “downrange” of the two landmarks, so you can line up the two marks visually while navigating along the line. If a GPS is available while you're under way, it can be used instead of a chart to line up with a landmark along a magnetic north/south or east/west line.
- 3). Line the boat up along the north/south line you have identified and run it toward the north. Adjust the port/starboard compensator until the compass reads exactly north.
- 4). Reverse course and run the boat due south along the same line. If the compass does not read correctly, do not adjust the compensator, but rotate the compass itself enough to remove one half of this error (called an alignment error.) Reverse course again and repeat Step 3, and then repeat this step until the compass reads correctly in both northerly and southerly directions.
- 5). Perform the same series of steps along the east/west line, adjusting the fore/aft compensator to point the compass due east or west when you are running in that direction. At this stage, any alignment error should have been removed in the previous steps, so rotating the compass should not be necessary.
- 6). Secure the compass in place after it reads accurately when running north, south, east and west. As long as nothing changes on the boat (such as adding another piece of equipment near the compass), the compass should remain accurate. It is a good idea to check the compensation accuracy once a year.
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