Choosing · 6 minute read
Motor cruiser autopilot installation
Plan motor cruiser autopilot installation: hydraulic pump sizing, voltage, hard-over time, heading sources, second stations and commissioning requirements.
Motor cruisers are, on paper, the easiest boats to fit an autopilot to. The steering is usually hydraulic, the boat is upright, the power supply is generous and the loads are predictable. In practice the decisions that matter are quiet ones: matching the pump to the steering cylinder, deciding where the control heads go, and thinking hard about what the boat will do if it follows a route without anyone watching.
This guide covers the choices for Australian power boats, from a plate-alloy fishing cruiser on the west coast to a flybridge boat of the sort built on the Gold Coast heading north to the Whitsundays for the winter.
Key facts
- Steering
- Hydraulic on most cruisers above about 8 metres
- Pump sizing
- Matched to the cylinder volume, not the boat length
- Voltage
- Many larger cruisers run 24 V; specify the pump to match
- Typical draw
- Roughly 1 to 2 A average under way on a well matched system
- Stations
- Control heads at the lower helm, flybridge and often the cockpit
- Route mode
- Powerful and the easiest way to run into something
Motor cruiser hydraulic steering and autopilot drive interfaces
On almost any motor cruiser above about eight metres, the wheel drives a hydraulic helm pump which pushes a cylinder on the rudder or outdrive. An autopilot joins that circuit with its own reversing pump, plumbed so it can move the cylinder without fighting the helm.
That plumbing is the job. The pump must be installed with correct pipe runs, a proper bleed, and check valves or a bypass arrangement to suit the system, and it must be the right displacement for the cylinder. Get the plumbing wrong and the symptoms look like a bad autopilot: spongy steering, slow response, and a pilot that overshoots.
Some smaller cruisers and many trailer boats still use cable steering, in which case the pilot drives the cable system or, for outboards, works through a dedicated outboard drive. The sizing logic is different and worth a separate conversation with the installer.
Pump sizing and the hard-over time
Autopilot pumps are rated by displacement, and the correct choice comes from the volume of the steering cylinder and the you want. The usual target on a power boat is a rudder that can go from full lock to full lock in a small number of seconds, because a pump that is too small makes a pilot that cannot keep up in a following sea, and one that is too large makes the steering feel twitchy and works harder than it needs to.
The cylinder volume is usually printed on the cylinder or published by the steering manufacturer. Give that figure to your dealer and let them specify the pump. This is not a place to guess or to reuse whatever was on the last boat.
Check the voltage while you are at it. Many larger cruisers run a 24 volt house system, and pumps and course computers are sold in both 12 and 24 volt versions. Fitting a 12 volt pump to a 24 volt boat via a converter is a compromise that rarely ends well.
Specify the pump from the cylinder, every time
Motor cruiser autopilot systems available in Australia
Garmin's Reactor 40 hydraulic system with is popular on planing cruisers and fishing boats, largely because Shadow Drive hands control straight back when the helmsman turns the wheel, with no button to press. The GHC 50 control head is a clear, simple interface and the system integrates with Garmin plotters.
Simrad's AP44 control head with a NAC-3 course computer is a common fit on boats with Simrad or B&G electronics, and virtual rudder feedback allows some installations without a rudder reference unit. Raymarine covers the range with the Evolution packs, from the EV-150 for smaller boats up through the EV-200 and EV-400 for larger vessels with bigger drives, all built around the EV-1 sensor core and an ACU matched to the drive.
Furuno's NavPilot 711C remains a favourite on serious cruising and fishing boats, with allowing installation without a rudder reference on suitable steering, and and changing how the pilot and helmsman share control. The right choice usually follows the plotter brand already on the boat, which keeps the network simple.
Motor cruiser second-station autopilot controls
The flybridge cruisers built in Queensland by yards such as Riviera and Maritimo, Victorian-built family cruisers, and the plate-alloy boats popular in Western Australia and the Northern Territory all share one requirement: the pilot has to be usable from more than one place.
That normally means a control head at the lower helm and another on the flybridge, with a wired or wireless remote for the cockpit. On a fishing boat, cockpit control matters more than anything, because that is where the crew is when the boat needs a course change.
Plan the stations before the installation rather than adding them later. Running one extra network drop during the fit-out is trivial. Retrofitting a control head into a finished flybridge console is not.
- Control head at the primary helm, within reach without leaving the seat
- Second head on the flybridge if the boat is regularly driven from up top
- A cockpit remote for fishing, anchoring and docking work
- Clear indication at every station of which one has control
- All heads and the course computer on the same network backbone
- A labelled autopilot breaker that any crew member can find in the dark
Motor cruiser route-following limits and manual takeover
Track and route modes are where a power boat autopilot earns its keep. The pilot holds the line between waypoints, corrects for current and wind, and tells you when the next leg is coming. Over a long day it steers a straighter course than any human, and a straighter course is less distance, less fuel and less fatigue.
It is also the easiest way to hit something. A route programmed at the dock does not know about the trawler working across it, the crab pot floats off Hervey Bay, the yacht beating out of the channel or the whale on the surface. The pilot will hold the line right up to the moment of impact with complete confidence.
The lookout requirement in the collision regulations applies just as much at twenty knots on autopilot as it does anywhere else, and speed compresses the time available to act. Route following is a navigation aid that frees your attention. The place to spend that attention is out the window.
Long-range cruising, north and across the top
A run up the Queensland coast is the classic Australian power boat passage, and it is exactly the use case autopilots were made for: long days at displacement or semi-displacement speed, following a route inside the Reef, with tidal streams that push the boat off a heading. , with cross-track alarms set sensibly, does that job far better than a person can for eight hours.
Across the top, from Cape York through the Torres Strait and on to Darwin and the Kimberley, the tides become the dominant factor and the value of true track holding rises further. Fuel planning and straight tracks are directly connected, and a pilot that holds the line is worth real money over a season.
For a boat doing this kind of mileage, buy for redundancy as well as capability: a system whose parts can be obtained in Cairns or Darwin, a spare fluid supply, and a helm that steers properly by hand if the pilot stops. Ask the installer for a handover that includes what to do when the pilot fails at sea, not just how to engage it.
Questions
Frequently asked
What size autopilot pump do I need?
It is set by the volume of your steering cylinder and the hard-over time you want, not by the length of the boat. Get the cylinder volume from the steering manufacturer and give it to your dealer so they can specify the pump. A mismatched pump is the most common cause of poor autopilot performance on motor cruisers.
Do motor cruisers need a rudder reference sensor?
Some systems require one and others can estimate rudder angle, including Furuno with Fantum Feedback, Simrad with virtual rudder feedback and many Garmin hydraulic installations. A real sensor still gives cleaner steering and better drive protection. Ask your installer what the current recommendation is for your exact model and steering.
Can I run an autopilot on a 24 volt boat?
Yes, and you should specify 24 volt components rather than converting. All the major manufacturers offer course computers and pumps in both voltages. Mixing voltages through converters adds a failure point in a safety-critical system.
Is it safe to follow a route on autopilot?
It is safe as a navigation aid and unsafe as a substitute for watchkeeping. The pilot will hold the programmed line regardless of traffic, crab pots, floating debris or whales, and at planing speed you have very little time to react. Keep a proper lookout, set an AIS closest point of approach alarm, and confirm each waypoint change deliberately.
Will an autopilot save fuel?
Usually yes, modestly, because it holds a straighter track than a helmsman does over a long day and distance saved is fuel saved. The bigger gain is reduced fatigue on long passages up the Queensland coast or across the top. Do not expect a dramatic figure, and do not let route following replace lookout.
Practise autopilot operation with an instructor
Habits are learned at the helm with someone watching. The training section explains what a good instructor covers and where to find one in your state.