MJM Yachts 36z Express - Manual (Page 7)

CHAPTER 1
Compass Heading & Calibration
There are 3 heading references for navigation on the 36z: (1) The compass on the dash, (2)
Autopilot digital compass, and (3) GPS COG (Course Over Ground). All of these headings should
be within a degree or so of each other when underway. If not, it is recommended that differences
be recorded on a deviation card after following the calibration method outlined below or
employing the services of a compass adjuster. Use COG as the primary reference at a time
when you are not influenced by wind/wave/tidal set. The digital compass sensor is located on a
stringer outboard to port under the cabin sole. It is accessible by opening the cabin sole hatch
and looking aft and to port.
Avoid storing steel or iron items such as tools next to it.
Ritchie Ship’s Compass Calibration Method
1) With the compass in its intended position, but not finally secured, select a course on your chart
using two identifiable marks, buoys or landmarks 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.
2) 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 until
the compass reads correctly.
3) Reversing direction, run the boat southerly, 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 and 2 and then recheck this Step 3.
4) Simply repeat the procedures of Steps 1, 2 and 3, except this time, using an east/west course
and the fore/aft compensator, although at this time any alignment error should have been
eliminated.
5) Upon completing the procedure, secure the compass in its final position.
Boat Speed Rather than a paddle-wheel or sonic device, the Raymarine C120 plotter is used
to generate SOG (Speed Over Ground) that is displayed by the chart-plotter and may also be
shown in larger digits on the Autopilot display. Eventually, you will learn to approximate boat
speed through the water by relating it to RPM on the tachometer.
1.4 TOWING Refer to the included ISO Owner’s Manual or to a book on seamanship and
boat handling for
towing guidelines.
1.5 HAULING OUT A facility that is unfamiliar with the 36z may require information before
hauling the boat with a Travel-Lift or crane & straps. Refer to the illustration included at the
back of this manual. The keel (centerline of the boat) and chines (edges) should be used to
position weight bearing supports. You will note that the fore and aft lift points are located
approximately at either end of the pilot house... e.g. abeam of the windshield and the aft end of the
hard top.
Point loading flat areas other than centerline and chine or setting the
weight of the hull on supports of insufficient area may result in damage to the hull.
OPERATION 6