ComNav P4 Installation and Operation Getting Started
Document PN 29010100 V1r0 - 117 -
It is always a good idea to check all the compasses on your boat, for accuracy in all
directions, on a regular basis - approximately once or twice a year - and before setting off
on any
long voyage. A good way to do a quick check is with any of the traditional “box the
compass” methods,
which every professional mariner should have learned as a novice.
Simply find some convenient ranges which have good cuts between them, and steer back
and
forth along them.
Steer various straight tracks, in as many directions as possible, between pairs of
charted objects. Determine the Coastal and Marine Geology (CMG) between various
plotted positions (with GPS, or with two or
three-bearing LOP fixes with a good Pelorus
or hand-bearing compass, etc.) on your
paper charts.
You might even want to do a box-the-compass confirmation right now, simply as a final
“double check”
of the compass setup you just completed.
Sea Trials
Sea Trials allow you to test out the basic functions of your P4 autopilot while
underway, and to
fine-tune the steering parameters for the best performance. The goal
is to achieve accurate course-keeping, and smooth, rapid changes of heading, without
excessive movements of
the boat’s rudder.
NOTE: before you begin Sea Trials, it’s a good idea to review how you steer your
vessel manually, and how that compares to how the P4 performs when
steering the
boat under autopilot conditions. Please re-read the chapter on “How Autopilots Work.”
During Sea Trials, you will test the default Steering Parameters of the P4 on your specific
vessel, and
make adjustments if necessary. When the Steering Parameters are properly
adjusted and fine-tuned for your boat, the autopilot
will do the same as you would
manually; which is to allow the boat to adapt to the body of water, yet still maintain as
straight a track as possible in the current conditions, on the desired heading or course.
NOTE: To accurately and successfully complete Sea Trials, you must be familiar with the
operation of the autopilot in AUTO mode and with the specifics of the Auto menu.
Sea Trial Procedure
The initial Sea Trials should be done in relatively calm conditions.
Adjust Rudder Gain and Counter Rudder for Hi Speed
1. Bring the boat up to a speed where the boat’s rudder (or steerable-thrust system,
such as
an outboard or I/O leg), provides sufficient steerageway that it has
accurate, firm control
of the boat’s direction of travel. Typically, this will be less
than your normal “cruising speed,” perhaps by quite a margin. For
many boats, this
will be around 7 Knots.
2. Bring up the Auto menu, highlight “Parameter Set” and select “Hi”.
3. If ALC is set to “On”, highlight it and set it to “Off”.
4. Start with “Rudder Gain” and “Counter Rudder” set to the factory defaults (for Hi): 5
and 3.
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