mjm yachts 50z Downeast, Owner'S Manual

Page: 9 / 72

CHAPTER 1
Compass Heading
There are 3 heading references for navigation on the 50z: (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. Use COG as the primary reference at a time when you are
not influenced by wind/wave/tidal set.
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.
1.5 Hauling & Blocking A facility that is unfamiliar with the 50z may require information before
hauling the boat with a Travelift 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 pilothouse... 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
Avoid storing steel or iron items such as tools nearby any compass.