Furuno NAVPILOT-500 Marine Instruments User Manual


 
4. MENU OPERATION
4-5
WEATHER
When the sea is rough, the boat’s heading fluctuates to port and starboard. If the rudder is
driven very often to maintain the set course, the helm mechanism may wear out. To prevent
this, the weather adjustment makes the NAVpilot-500 insensitive to minute course
deviations. You may choose a degree between 1° to 10°. Until the course deviation exceeds
the selected setting, steering to correct the heading will not be initiated.
The illustration below shows boat’s track lines with weather setting 3° and 7°. When 7° is
set, for example, the rudder is not driven until the course deviation exceeds 7°. Increasing
the setting reduces activation of the steering gear, however the boat tends to zigzag. When
the sea is calm, set a smaller value.
7
3
Weather = 3 Weather = 7
Track line and weather setting value
RUDDER GAIN
When the boat’s heading deviates from the set course, the NAVpilot-500 adjusts the rudder
to correct it. The rudder angle (number of degrees) which is steered against every degree of
course deviation is known as the rudder gain.
The following illustrations show how many degrees the NAVpilot-500 steers the rudder in
order to nullify 10 degrees of course deviation with various settings of the rudder gain.
Rudder gain = 0.1
Rudder gain = 0.3
Rudder gain = 0.8
Rudder angle = 10 x 0.1=1
Rudder angle = 10 x 0.3= 3
Rudder angle = 10 x 0.8= 8
10
10
10
Rudder angle and rudder gain setting