Furuno NAVpilot-700 Operator's Manual page 74

4. HOW TO CUSTOMIZE YOUR NAVPILOT
[RUDDER GAIN]: When the boat's heading deviates from the set course, the NAVpilot
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 steers the rudder in
order to nullify 4 degrees of course deviation with various settings of the rudder gain.
Rudder gain =
4°
Rudder angle = 4° x 1=4°
Set rudder gain so that the boat does not make frequent yaw. The figure shown below
provides general guidelines for setting rudder gain.
Fast
Calm
Light
Low
[COUNTER RUDDER]: If the boat is heavily loaded, the heading could change exces-
sively because of inertia. This phenomenon causes the vessel to "overshoot" the in-
tended course. If this happens, the NAVpilot will steer the rudder to the opposite side
and the heading will turn in opposite direction excessively again. In an extreme case
the heading oscillates several times until it finally settles in the new course. An adjust-
ment known as "counter rudder" prevents this kind of oscillation.
Counter rudder is usually not required for small boats. When your boat zigzags a lot
before settling in the new course, increase the counter rudder setting.
4-4
1° Rudder gain =
4°
Rudder angle =
Speed
Sea State
Load Condition
RUDDER GAIN
2° Rudder gain =
4° x 2=8° Rudder angle =
Slow
Rough
Heavy
High
3°
4°
4° x 3=12°