ComNav Commander P2 - Changing Wind Angle; Low Wind Speeds; Tack & Gybe Inhibit

ComNav Commander P2 & P2VS Installation & Operation Advanced Operations
Document PN 29010074 V4.1 - 153 -
Changing Wind Angle
To change the Commanded Wind Angle, rotate the
C
C
O
O
U
U
R
R
S
S
E
E
C
C
H
H
A
A
N
N
G
G
E
E knob. The angle will
change by 1° for every click of the knob.
 Important! Turning the
C
C
O
O
U
U
R
R
S
S
E
E
C
C
H
H
A
A
N
N
G
G
E
E knob, tells the autopilot to turn the
boat in the direction you turn the knob. But keep in mind that the change in
the Commanded Wind Angle depends on the Tack you are on:
• On Port Tack, turning knob clockwise (thus turning the boat to Starboard)
increases the Commanded Wind Angle, since the boat will turn farther away from
the wind. Similarly, turning the knob counter-clockwise turns the boat to Port,
and so decreases the Commanded Angle.
• On Starboard Tack, it is the opposite way around.
Of course, as the boat turns you should also trim your sails to suit the new wind angle!
Tack & Gybe Inhibit
The 045° to 160° wind angles for the “ WIND mode entry range” are in fact the Close Haul &
the Gybe Hold angles, respectively. The actual values of each of these points of sail can be
changed, in the Wind menu, if you wish – and if you do so, the “entry range” will change too.
However, attempts to change the Commanded Wind Angle beyond these Points of Sail (i.e.,
less than Close Haul or more than Gybe Hold) will be ignored. This is a safety feature known
as Tack and Gybe Inhibit.
 Caution! These Inhibits are not a guarantee against hazardous situations.
When sailing under autopilot control, your attention is required at all times,
most especially when running or beating.
The Tack and Gybe Inhibits are meant to prevent unintended, accidental Tacks & Gybes.
However, there is a way to perform Tack and Gybe manoeuvres intentionally , using the
T
T
U
U
R
R
N
N button – see pages 156 & 159.
Low Wind Speeds
A warning will appear on the screen any time the wind speed is below about 9 – 10 Knots
38
;
for example, in Figure 97, the display would show “Low Wind” instead of “App. Wind”.
The reason for this warning is that sailing in light winds (below about 6 Kn, on a typical
sailboat) under autopilot control can be very tricky. The boat speed will be low, and so there
will not be sufficient steerageway for the autopilot to control the boat’s direction properly.
However, the autopilot will still try to do its best in a Low Wind condition – and so the warning
is to remind you that it may not have very good control of the steering!
When the wind speed is above 9 – 10 Kn, the low wind warning will be replaced with either
“App. Wind” (Apparent Wind) or “True Wind” (determined by the Wind Source parameter).
• If the wind speed drops to about 3 Kn, a “Wind Sensor Error” alarm will occur. In this
condition, the wind speed is too low to maintain the Commanded Wind Angle, and so
the autopilot will instead try to maintain the Heading the boat was on just before the
alarm occurred. Typically, this will cause the rudder to move gradually to the Dead
Ahead position
39
.
• This alarm will also occur when using a Wind Vane, if the vane fails.
• When using an NMEA source, this alarm will occur if there are no valid wind data
sentences received for ~2 seconds.
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There’s a 1 Kn hysteresis on the Low Wind & Wind Sensor Error detections, to reduce annoying warnings & alarms
around the thresholds.
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If there is also a problem with the RFU, the autopilot will simply keep the rudder at the same position it was at.