COURSEMASTER CM82i User guide

COURSEMASTER
AUTOPILOTS
A
ustralia's world leader in autopilot technolo
gy
CM82iSYSTEM MANUAL
11-09

CM82iSYSTEM MANUAL
Your Coursemaster CM82iautopilot system is engineered for accurate and
reliable steering. But remember that it cannot keep a lookout.
SAFE NAVIGATION IS ALWAYS YOUR
RESPONSIBILITY.
COURSEMASTER AUTOPILOTS PTY LTD.
2/66 LOWER GIBBES STREET,
CHATSWOOD NSW. AUSTRALIA 2067
ABN 25 001 306 369
Phone [phone]
Fax [phone]
E-mail [email protected]
Website www.coursemaster.com
Copyright 2009. This manual, the mechanical and electronic design of the CM82i
autopilot system and its associated software are protected by copyright. Unauthorised
copying may result in prosecution.
11-09

QUICK START
•Press the STANDBY key to turn the system on.
•Hold down the STANDBY and PILOT keys together to turn the system off.
•Steer to the desired course and press PILOT.
•Use the arrow keys to change course.
•To engage the auto-navigate system, hold the PILOT key down for two
beeps. Press PILOT once to cancel the auto-navigate mode.
•To select the menu, hold the STANDBY key down for two beeps. Scroll
down with single presses of the STANDBY key. Hold the STANDBY key
down for two beeps to exit the menu.

CM82iSYSTEM MANUAL
CONTENTS
QUICK REFERENCE
1. SYSTEM DESCRIPTION
1.1 Introduction to autopilots 1-1
1.1.1 Conventional autopilots 1-1
1.1.2 Steering Control 1-3
1.1.3 The ‘intelligent’ autopilot 1-4
1.1.4 Course holding and turning 1-4
1.1.5 Options 1-5
1.1.6 Working with other Equipment 1-5
1.2 The CM82iSystem 1-6
2. OPERATING INSTRUCTIONS
2.1 The Control Head 2-1
2.2 Getting Started 2-2
2.3 Normal Operation 2-3
Switching on
Switching off
Autopilot
Adjusting the course
Auto-navigate
2.4 The Menu 2-6
2.5 Alarms 2-11
2.6 Recommended settings 2-12
3. INSTALLATION
Step-by-step Summary 3-1
3.1 Junction Box 3-2
3.2 Control Head 3-4
3.3 Rate Gyro Compass 3-5
3.4 NMEA Interfaces 3-7
3.5 Steering Drive 3-8

CONTENTS
4. TROUBLE-SHOOTING
4.1 General 4-1
4.2 Error messages 4-2
4.3 Other faults 4-3
4.4 Fuses 4-4
5. SYSTEM SPECIFICATIONS 5-1
6. MAINTENANCE AND WARRANTY 6-1
QUICK REFERENCE
INSTALLATION
•Mount the Junction Box as described in Sect 3.1
•Mount the Control Head as described in Sect 3.2
•Mount the Compass as described in Sect 3.3
•Install the Steering Drive as described in Sect 3.5.
•Connect optional attachments as described in Sect 3.4
•Carry out the system set-up as described in Sect 2.2

THE MENU
BACKLIGHT
NORMAL/ROUGH
RUDDER FACTOR
RATE FACTOR
RATE GYRO ON/OFF
HEADING CONTROL HEADING ADJUST
AUTO COMP CALIB
MANUAL COMP CALIB
MAG VARIATION
HEAD COMP/HDG/HDT
RUDDER CONTROL HELM LIMITS
TURN RATE LIMITS
AUTO BALANCE ON/OFF
STEER DRIVE
HELM ALERT
OTHER OPTIONS NMEA OUT HDG/HDT
PILOT DISPLAY A/B
COMPASS VOLTAGES
BALMONITORON/OFF
COLD START

1 SYSTEM DESCRIPTION
1.1 INTRODUCTION TO AUTOPILOTS
The main function of a marine autopilot is to hold the heading of a vessel on a
reference course which is held in the memory of the autopilot. When it is operating,
the autopilot continuously compares the vessel’s heading with a reference course, and
if they are different, it applies helm to bring the vessel back on course. Since there has
to be a compromise between the accuracy of course holding and the activity of the
rudder, the autopilot has controls which are set to strike a balance between these two
factors.
1.1.1 CONVENTIONAL AUTOPILOTS
A conventional autopilot is illustrated schematically in Fig 1.1
RUDDER
STEERING DRIVE
RUDDER STEM
CONTROL
POWER
TRANSDUCER
COMPASS
Figure 1.1 Basic components of a conventional marine autopilot.

System Description 1-2
The four basic components are a compass, an electronic control box, a rudder angle
sensor (transducer) and the steering drive.
A Junction Box, mounted below decks, contains most of the system electronics and a
Control Head, mounted at the steering station provides the interface with the user.
Modern autopilots perform other functions as well and this introduction explains how
these fit in with the basic function and how they provide a wider range of options for
the user.
When the autopilot is first turned on, it rests in an idle (STANDBY) state in which it
displays the heading, but does not steer the vessel. It is activated by switching it into
the PILOT state. At the moment this is done, the current heading is put into memory
as the reference course and the autopilot starts steering to hold the heading on this
reference course. The user can change the reference course at any time and the
heading will swing round to match the new course.
There is another way of setting the reference course. If the autopilot is connected to a
GPS navigation receiver, the heading is then controlled to place the vessel on a direct
track between the origin waypoint and the next waypoint.
1.1.2 STEERING CONTROL
When the vessel swings off course or the reference course is changed, the autopilot
should apply helm in a way, which brings the vessel onto course quickly, but without
overshooting the reference course. The correct rudder angle depends on the amount
of the error, the speed of the vessel, its size, the effectiveness of its rudder and the
weather conditions. This choice is managed by four parameters within the autopilot,
as follows.
Rudder Factor
The sensitivity or Rudder Factor sets how many degrees of helm are applied for a
given course error. A mid-range Rudder Factor setting applies half a degree of helm
for each degree off course. In large or slow vessels it would be more and in light, fast
boats it may be less.
Setting the rudder factor too high causes oversteering or ‘snaking’ as illustrated in Fig
1.2. Too low a setting causes understeer and a sluggish response. Fortunately, most
vessels tolerate a range of settings and still steer well.

System Description 1-3
UNDERSTEER
REFERENCE
COURSE
OVERSTEER
Figure 1.2. Illustration of oversteer if the rudder factor is set too high and understeer if
it is set too low.
Counter Rudder
Counter Rudder, or rate feedback, compensates for turning inertia and is generally
used in vessels above 8 m length. Near the end of a turn, counter rudder is applied to
slow the turn rate so that the heading settles accurately on the new reference course.
Counter rudder also improves stability in a following sea.
The action of the rate or counter-rudder during a turn is illustrated in Fig 1.3.
Generally, when the rate component is increased, vessels hold a course better but
react to changes in the reference course more slowly. Counter-rudder also improves
control for most vessels operating in a following sea.
REFERENCE
COURSE
NORMAL RUDDER
NEUTRAL RUDDER
COUNTER RUDDER
Figure 1.3 Rudder action during a turn in the RATE mode.

System Description 1-4
Sea State
When the Sea State or Control Mode is set to ROUGH, it introduces a ‘deadband’ in
the course control, so that rudder activity is reduced when the vessel rolls and yaws in
a heavy sea. Full rudder control is applied when the vessel yaws off course by more
than a preset amount.
Trim
Vessels often show a steering bias or offset, which can be due to weather, propeller
torque or towing a load off-centre. The autopilot responds to this by progressively
trimming the centre position of the rudder until the average heading of the vessel
equals the reference course.
1.1.3 THE ‘INTELLIGENT’ AUTOPILOT
An ‘intelligent’ autopilot, such as the CM82i,works on the same principles as those just
described, but with two practical differences. There is no rudder angle sensor. Instead,
the angle is calculated within the system, using inputs from the steering drive and the
compass. Secondly, some internal settings in the autopilot adapt themselves
automatically to conditions such as propeller torque and offset effects arising from the
weather and the trim of the vessel.
1.1.4 COURSE HOLDING AND TURNING
The CM82i is mainly intended for vessels in the 5 - 10 m range, usually with outboard
motors. These vessels have two features that affect course holding and turning. First,
they are more responsive to wind load and wave effects than heavy vessels and can
yaw quickly when hit by a wind gust, for example. Secondly, they are often used at
speeds above 15 kt and are therefore susceptible to the southerly/northerly heading
error effect.
The autopilot responds quickly to correct heading shifts caused by wind or waves and
a yaw of 3 degrees around the reference course is typical in choppy and windy
conditions. But when there is a constant weather offset, the automatic trim acts
progressively to apply weather helm and bring the average heading of the vessel onto
the reference course. This action may take 10 - 15 seconds to complete. The weather
helm effect can be seen particularly during a large course change. If the conditions
are not calm, the wind and wave load on the vessel will be different at the end of the
turn and the vessel may undershoot or overshoot the new reference course until the
trim adjusts to the new conditions.