easy calculations and adjustments 67
- Remove index error. Set the micrometer drum and index arm to zero. Look
through the scope at the horizon or a distant horizontal surface. If you see a
broken line, you must make this adjustment.
Set your tool into the horizon glass screw closest to the sextant frame. Now
look at the horizon again and slowly turn the setscrew up or down until you
see a straight line.
Always make a fi nal adjustment check. Go back and check all three adjust-
ments again, and if necessary, repeat steps 1 through 3. Remember, you must
go through all three adjustment steps in the order shown.
How to Adjust Your Radar for the Best Picture
No other electronic instrument off ers the versatility or multitasking of the
modern radar. It gives navigational information, tracks targets, allows entry
into port during fog, and warns of approaching squalls and storms. (Chapter
7 includes tips on using radar for collision avoidance.) Newer radars even
interface with GPS receivers and chart plotters.
Most modern radars have automatic tuning, but knowing how to adjust
yours manually puts you in control and oft en gives a sharper picture.
THE FIVE MAIN CONTROLS TO GET YOU STARTED
Brilliance: Adjust how bright the monitor and text look. Use this control as
you would use any computer screen brightness control.
Contrast: As on a computer screen, the contrast control changes the vibrancy
of an image or text. Increase contrast to sharpen images and text. Decrease
contrast for a soft er eff ect.
Gain: Th is is the system’s main receiver control. Gain measures the ability of
the receiver to process the refl ected signal properly. Use the gain control to
tweak the radar for a good picture.
Sea clutter (STC): Use this control to clear up screen clutter caused by signal
refl ections from wave or swell faces.
Rain clutter (FTC): Use this control to clear up screen clutter caused by signal
refl ections from rain, squalls, or storms.
START WITH A WARM-UP
If you’ll use the radar with the engine running, start your engine or engines.
Turn on all electronic gear. Then turn on the radar receiver. Wait 2 to 3
minutes before beginning adjustments.