Edgewater Networks 240IS, Owner'S Manual

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Compensation
A built-in correcting magnet system consists of two sets of magnets fixed to two adjusting rods with slotted ends. The
slots should be horizontal before starting the adjusting procedure. A small non-magnetic screwdriver is provided for
this purpose.
Before starting compensation, make sure you have a suitable location (see Testing Your Chosen Location).
B-51, B-51G, B-51W, B-51-A, RA-91, F-50, F-50W & D-55
(see below for V-57’s, S-53’s & RA-93)
Method 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 (See example).
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 mark
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.
Method 2. (Requires the use of GPS or Loran)
In this method, you will be using a GPS or Loran as your reference.
1. Your GPS or Loran must be set to provide you with Magnetic, not True headings. Check your Manual.
2. GPS and Loran 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.
3. Because the GPS and Loran calculate COG based on current and past positions you will see greater heading
accuracy while traveling at higher speeds. We recommend at least 10 knots.
Step One.
While at sea, with the compass in its intended position, but not finally secured, (see Mounting the Compass),
obtain the Loran/GPS bearing to a fixed aid or landmark that is within 10
o
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) until the compass heading matches the Loran/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).
LIGHTHOUSE
DOWN RANGE
TOWER
EXAMPLE
LIGHTHOUSE