5.0 SEA
TRIALS
Initial sea trials should be carried out in calm
conditions and with plenty of sea room. The
previously conducted functional test will have
verified that the autopilot is operating correctly
and that you are familiar with all of its controls.
Check that the gain control on the rear of
the control unit is adjusted to the setting
recommended for the particular vessel category
given in Fig. 3.1, Then set the
Sea
control to ‘0’
and the
Rudder
control to ‘4’.
Initial sea trials on fast planing vessels
should be conducted at no more than half
engine throttle under which conditions the
recommended mid-way setting of the rudder
control should give acceptable steering
performance. A mid-way setting of the rudder
control will also give acceptable steering
performance in sailing and displacement power
vessels under all conditions for initial trial
purposes. Fine setting of the
Rudder
control is
discussed later.
5.1 FIRST TRIALS
.The following initial trial procedure is
recommended:
Steer manually on to a fixed heading and
hold the course steady.
Switch the autopilot to
Set
and allow up to
1.5 seconds for the compass to adjust
automatically to the manually steered
heading.
Switch to
Duty
and the autopilot will
automatically take control. In calm
conditions an extremely constant heading
will be maintained.
Increase the setting of the
Sea
control until
a good heading is achieved with a minimum
number of wheel movements. Correct setting
of this control for varying sea conditions is
essential to avoid unnecessary wear and
tear on the autopilot and to minimise
electrical power consumption.
Alter course to port or starboard using the
Steer
control on the main control unit, (or
the
Left/Right
control on the auxiliary
control unit with the main control unit
switched to
Remote).
Major course
alterations are best applied by switching to
Set
and then manually steering the vessel
on to the new heading. When the new
course is acquired, hold for a few seconds
and then switch the autopilot back to
Duty
to maintain the new heading.
If a hand-held remote control is fitted, switch
from
Auto
to
Manual
and then power steer
the vessel by the control wheel. Switch back
to
Auto
and the vessel will return promptly
to the original heading.
When the autopilot is set to
Duty
return to
manual steering may be instantly achieved
by switching to
Set
or
Off
on the main
control unit. It is very important to remember
that manual control can only be obtained on
the auxiliary control unit if the main control
unit is switched to
Remote.
The importance
of being able to regain manual control of
steering must-be stressed. The
Off
button is
red for easy identification and
manual take-over procedures should be
at an early stage.
5.2 RUDDER CONTROL ADJUSTMENT
The gain control on the rear of the control unit
has been previously set according to the
recommendation given in Fig. 3.1. This control
sets the range of adjustment available on the
main panel
Rudder
control and in all but
extreme cases should not need further
adjustment.
In all cases, excessive rudder application
results in ‘oversteer’ which can be recognised
by the vessel swinging slowly from side to side
of the controlled heading. In addition, distinct
overshoot will be observed when the course is
changed. This extreme condition may be
corrected by reducing the
Rudder
control
setting.
Similarly, insufficient rudder application will
result in sluggish steering response which is
particularly apparent when changing course
using the
Steer
control. This condition is
corrected by increasing the
Rudder
control
setting.
Oversteering and understeering tendencies
are most easily recognised in calm sea
conditions where wave action does not mask
basic steering performance.
The operational adjustment technique for the
Rudder
control varies significantly between
planing and displacement craft and is
described separately below.
5.2.1 PLANING
Planing craft operate over a very large speed
range. Rudder effectiveness increases very
significantly at higher hull speeds and it is thus
necessary to reduce the
Rudder
control setting
as speed increases to avoid oversteer. In
normal cases the rudder control setting would
be reduced almost to
at maximum planing
speed and increased towards ‘7’ at minimum
displacement speeds. Oversteer can be
extremely violent at planing speeds and it is
thus essential to reduce the rudder setting
before opening the throttle.
