Seastate; Autotrim; Configuration; Scaling - Simrad Navico Wheelpilot WP10 Manual

2.7 Seastate

In rough weather, more variations in heading will be
detected by the Wheelpilot due to the heavy seas
yawing the vessel. If no account of this was taken,
then the Wheelpilot would be overworked, causing
unnecessary strain on the unit and excessive drain
on the batteries. All Simrad Wheelpilots will contin-
uously monitor corrections applied to the wheel
over the course of a voyage, and allow a Òdead
bandÓ within which the boat can go off course with-
out corrections being made (Fig 2.6).
The dead band is automatically set and updated
by the Wheelpilot to give the best compromise
between course holding and battery consumption.
However, this can be manually set if so desired.
To manually adjust the Seastate, please refer to
section 3.4.

2.8 Autotrim

Under differing conditions a rudder bias (sometimes
known as standing helm or rudder trim) is applied
in order to steer a straight course. An example is
when sailing close hauled where the vessel will nor-
mally pull into the wind, and the helmsman applies
a standing helm to leeward in order to maintain
course. The amount of this standing helm varies
according to factors such as strength of wind, boat
speed, sail trim and amount of sail set. If no account
of these were taken, then the vessel would tend to
veer off course, or pull round head to wind if sailing
close hauled.
The Wheelpilot continuously monitors the average
course error and applies a bias to the wheel to com-
pensate until the optimum condition is reached.
This bias or standing helm is applied gradually, so as
not to upset the normal performance of the
Wheelpilot. Thus, it may take up to a minute or so
to fully compensate after changing tack. Once opti-
mum trim is reached, the pilot will still monitor for
changes in the prevailing conditions and update the
trim accordingly.
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F
ig 2.6 - Seastate "deadband"
3

Configuration

3.1 Scaling

Before using the Wheelpilot, it is necessary to pro-
gram in the steering sensitivity, which is related to
the number of turns that the wheel makes between
end stops. This will determine the amount of
steering correction the Wheelpilot applies.
With the power OFF, press and hold the TACK
and CAL keys and switch on the power. Both
Port and Starboard LEDs will illuminate, the Cal
LED will flash, and a repeated sequence of beeps
will be heard. The number of flashes and beeps in
the sequence indicates the current scaling factor.
The scaling factor is the total number of half turns
from lock to lock. For example, if the wheel has
three complete turns from lock to lock, the scaling
factor will be 6. If there are 1 1 Ú turns from lock to
2
lock, then the factor will be 3.
Setting Turns Lock To
( No. beeps/flashes ) Lock
2 1
3 1 1 Ú
2
4 2
5 2 1 Ú
2
6 3
7 3 Ú
1
2
8 4
9 4 1 Ú
2
10 5
Press the Starboard key to increase the scaling fac-
tor by one, to a maximum value of 10 (= 5 turns
lock to lock). Press the Port key to decrease the
scaling factor by one, to a minimum value of 2 (= 1
turn lock to lock).
To confirm scaling setting and return to Standby
Mode, press the CAL key.
TACK
TACK
STBY STBY
AUTO
NAV NAV CAL
POWER ON
TACK
STBY
STBY
AUTO
CAL
TACK
STBY
STBY
AUTO
NAV CAL
NAV
Fig 3.1 - Reducing scaling factor by one
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