Ritchie S-OFF90 Installation And Maintenance Instructions

S-OFF90
Installation, Compensation, and Maintenance Instructions
Made in U.S.A.
CAUTION:
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 deviation. 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. 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.
Please read the Instructions completely before beginning installation.
The S-53-OFF90 is a specially designed compass for a unique application. THIS COMPASS SHOULD
NOT BE USED FOR ANYTHING OTHER THAN ITS INTENDED APPLICATION. It was designed to be
mounted facing the Port side of the vessel. The compass dial reads 90 degrees out so that when you
reference this compass you get the actual magnetic heading of the boat.

Testing Your Chosen Location

Use your compass to test a location. There are two brass rods near the bottom of the compass, which rotate 360
degrees; the slotted ends may be all that is visible. These compensation rods are used to correct your compass
for deviation. When testing a location, you do not want pre-set corrections in your compass, so neutralize the comp-
rods by setting the slots in a horizontal position.
Begin your test by holding the compass away from any possible interference and observing the compass reading.
Then move the compass into position carefully; keeping it pointed in the same direction. If the compass reading is
different without a change in direction you are observing deviation. You need to find a location that has less than 20
degrees of deviation on the 4 cardinal points if you intend to adjust your compass using the compensator rods.
After finding a location you should test for intermittent changes in the magnetic field. With the compass mounted
temporarily in its intended position try moving the steering wheel, throttle controls or anything else that might cause
deviation. It is also advised to turn electrical devices off and on. Please be advised that a changing magnetic field
cannot be corrected with compensation and you will need to find another location for your compass.

Installation (all Models)

Mounting the Compass

Great care must be taken to mount the compass so that it is aligned exactly 90 degrees to the keel of the boat.
Due to variations in bulkhead and deck materials, mounting screws are not supplied. Use hardware that is suitable for
your specific installation. SELECT MOUNTING HARDWARE THAT IS NON-MAGNETIC. Most quality stainless steel
and solid brass fasteners can be used. If you are unsure test them with a magnet.
This unit has a built-in lights which will require routing the wire or wires to your power source. To assure a clean
installation you may want to wait and drill the routing holes after you are satisfied with the compass alignment.
Specific model installation instructions are as follows:
Remove the base by "squeezing" the buttons on the side of the housing while carefully pulling on the base. Mount the
base as instructed (see Installation above). Re-install the compass and begin compensation (see Compensation
instructions below). Note: the mounting holes for this model are slotted, so by centering the mounting screws within
the slots you can install all screws and make your alignment corrections later.
Mounting pads are provided if you do not wish to drill any holes. Remove the mounting pads from their backing and
stick them over the mounting slots. Because alignment is difficult to verify at this time we suggest temporarily
securing the base (masking tape works well) until after compensation. After alignment has been verified, make a
small pencil mark at the front and back of the compass and deck. Remove the remaining backing from the pads and
secure the base to the deck using the pencil marks as a reference.
Note: The light wire can exit the compass either through the back or down through the bottom.