All Magnetic Compasses are vulnerable to magnetic interference, which will produce errors, called deviation. It is the Owner/Operator and/or Helmsman’s responsibility to make sure the compass is properly installed and compensated. Compensation is the act of correcting for MAGNETIC deviation aboard your boat. Every boat has its own "magnetic signature", magnets (speakers, microphones etc.), ferrous metals (steel, iron, etc.) and current carrying devices are common causes of deviation. It is important to understand that magnetic compasses point toward Magnetic North unless they are "deviated" by othe magnetic influences
NOT TO BE CONFUSED WITH TRUE NORTH. There is a difference between Magnetic North and True North, and that difference is called variation. Variation differs depending on your geographical location and can be determined by referring to a local chart. THESE INSTRUCTIONS DO NOT PERTAIN TO VARIATION.
We highly recommend using a professional compass adjustor, however if that is not feasible here are some basic instructions on how to adjust your compass.
FOR SAFETY AND ACCURACY, FOLLOWING ANY OF THESE INSTRUCTIONS IT IS NECESSARY TO HAVE AT LEAST TWO EXPERIENCED HELMSMAN ON BOARD THE VESSEL DURING THE COMPENSATION, AT LEAST ONE PERSON TO STEER THE VESSEL AND KEEP WATCH FOR HAZARDS AND ONE PERSON TO PERFORM THE COMPENSATION.
METHEOD 1 . (Preferred)
STEP ONE. With the compass in its intended position, but not finally secured, (see Mounting the Compass) select a course on your chart using two fixed aids that are within ten degrees (10°) of the North/South line. Try to select this course so that you can maneuver your boat “down range” of the marks selected.
STEP TWO. From a position down range of the North/South marks, and keeping the marks lined up, run the boat visually along the Northerly course selected. Turn the port/starboard compensator (slot is facing starboard) until the compass reads correctly.
STEP THREE. Simply repeat steps 1 & 2, except this time, using an East/West course and the fore/aft compensator (slot is facing aft).
STEP FOUR. Check compass alignment by running the boat in a Southerly direction, again keeping the marks lined up. If the compass is not correct at this time, there is an alignment error. To correct, rotate the compass itself to remove one half of this error. Repeat steps 1, 2 & 4 until your North/South line is correct then repeat step 3.
STEP FIVE. Install fastener (s), taking care not to disturb alignment.
METHEOD 2. (Requires the use of GPS)
In this method you will be using a GPS as your reference.
1. Your GPS must be set to provide you with Magnetic, not True headings. Check your Manual.
2. GPS provide headings based on COG (course over ground). Compasses provide heading based on the direction the boat is actually pointed. Because of Tides, Currents and Winds, the boat may not always point in the same direction as COG. Pick a time and location that will minimize these effects.
STEP ONE. While at sea, with the compass in its intended position, but not finally secured, (see Mounting the Compass), obtain the GPS bearing to a fixed aid or landmark that is within 10 DEGREES of a North/South line.
STEP TWO. Position your boat along that line and steer directly at that mark. Turn the port/starboard compensator (slot is facing starboard, THE PORT/STARBOARD COMPENSATORS ONLY AFFECT NORTH-SOUTH) until the compass heading matches the GPS bearing.
STEP THREE. Simply repeat steps 1 & 2, except this time, using an East/West course and the fore/aft compensator (slot is facing aft, THE FORE/AFT COMPENSATORS ONLY AFFECT EAST/WEST)
STEP FOUR. Check compass alignment by running the boat 180 degrees from the heading used in step 2. If the compass is not correct at this time, there may be an ALIGNMENT ERROR.
To correct for an alignment error, rotate the compass itself to remove one half of this error. Repeat steps 1, 2 & 4 until your North/South line is correct then repeat step 3.
STEP FIVE. Upon completing the procedure, secure the compass in its final position. If you feel that the deviation on your boat is of an unusual nature, the services of a professional compass adjuster will be a wise investment.
To assure accuracy on all headings, check for deviation every thirty degrees and record any deviation on a deviation card. We recommend checking at the start of each boating season, and any time new equipment is added near the compass, for deviation
Protect your compass from the sun when not using your boat. Strong sunlight may decrease the life of your compass. Custom fit covers are available for Ritchie compasses. To remove salt spray deposits or dirt, rinse the entire compass with clean, fresh water and wipe carefully with a damp cloth.
Important Note: Never Use Chemical or Abrasive Cleaners to clean your compass.