Simrad Autopilot Guide

Simrad AP44:  This complete autopilot pack includes everything you need to upgrade your boat with a Simrad Continuum autopilot system. Set your heading and access advanced pilot modes with the intuitive AP44 Autopilot Controller, featuring a 4.1-inch full colour display and rotary control dial. Designed for hydraulic-steered outboard and sterndrive vessels up to ten metres (35 feet) in length, this medium-capacity pack also includes an RPU-80 hydraulic steering pump, NAC-2 autopilot computer, Precision-9 solid-state compass, plus all necessary NMEA 2000® cables and connectors.

Simrad AP48: The AP48 Autopilot Controller is a premium dedicated control head for Continuum autopilot systems, enhanced with modern glass helm styling. Engineered for responsiveness and ease of use in all conditions, the AP48 pairs a large aluminium rotary control dial with dedicated ‘dodge keys’ to adjust heading port or starboard in one- or ten-degree increments. With an optically bonded 4.1-inch display and its intuitive controls, the AP48 also provide full access to advanced Continuum steering features including automated turn patterns, No Drift steering, depth contour tracking, and more.

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Autopilots

Whether or not you plan any large passages, or do your boating locally, an autopilot enhances your time afloat. 

At its simplest, an autopilot is a system that maintains a boat's heading on a chosen course, but it offers a lot more besides. Or to put it another way, it acts just like a second pair of hands while you are driving the boat. To understand the benefits, let's take a more detailed look.

What is an autopilot?

An autopilot steers the boat for you by:

• knowing which course is required via manual commands from a person who is driving the boat or automatic inputs from electronic navigation equipment
• understanding which way the boat is headed by receiving inputs from a heading sensor and drawing from other dynamic data if integrated with a full marine electronic system
• applying changes to the steering system to keep the boat on its desired course

The most basic autopilot controls have always been buttons or rotary controls to tell the system to activate, hold the current course, or steer left or right. Modern autopilots can also automatically follow charted courses if integrated with marine charting and position fixing equipment.

Early leisure autopilots used to have additional controls on the fascia to fine-tune the response of the system, such as the rudder rate (how fast the steering reacts). You may still find some of these units on boats built in the 1960s-1980s. Mastering these settings to achieve a steady course in all sea conditions was something of an essential part, albeit a very satisfying one. 

Evolving Technology

Modern autopilot systems do still rely on initial calibration and set-up to work well, but they have built-in intelligence that enables them to learn how any given sea state, wind, vessel speed, loading and engine setting is affecting the boat. In any 'driving in a straight line' shoot out between a human and an autopilot in charge, the autopilot would normally win without constant pressing of buttons to adjust settings.

Speaking of buttons, in the Simrad® fully integrated world of marine electronics, you can now control your autopilot from multiple dedicated controllers, multi-function displays (MFDs) and wireless controllers.

What's in the box?

If you have a small motor launch or sloep where you steer the boat using a tiller, then Simrad® has a range of completely integrated tiller pilots where everything is packaged as one unit.

Most motorboats though use a component-based system, with many options to deal with a very wide range of boat sizes and types. Here's what a typical installation looks like:

• The autopilot computer – typically a black box that is installed out of sight. It forms the heart of the system.
• One or more standalone autopilot controllers or MFDs to control the autopilot – Simrad® also offers wireless controllers. As a minimum you should plan to be able to control the autopilot at any driving position where you operate the boat.
• An electronic heading sensor to generate direction, rate of turn and other dynamic information that assist autopilot performance. This might use solid-state electronics to read the Earth's magnetic field and boat movement, or additionally receive GPS satellite data for enhanced performance.
• A drive unit to control the boat's steering. This is typically either a hydraulic pump or steering ram with different versions available to suit outboards, sterndrives, IPS drives and rudders.
• A feedback unit to sense where the rudders or drives are pointed – this is not always required on Simrad ® autopilots.

Autopilot installation and calibration is possible by a competent boat owner. However, if in any doubt then talk to your local Simrad® dealer to ensure you get the very best out of your purchase and have a safe system that you can rely on.

What would I use an autopilot for?

• Safety
• Convenience
• Efficiency
• Short-handed boating

Safety

An autopilot looks after accurate course keeping, freeing up your attention to maintain a good lookout for other boats and hazards, monitor instruments and cross-reference your navigation information.

Maintaining a constant heading is of great help in assessing the risk of a collision with another vessel. If your heading remains the same and the target you are concerned about stays at a constant bearing in relation to your boat (visually or on radar), then it's time to take early action. If you drift either side of your course it's harder for you to visualise what is happening and also harder for the other boat or vessel to work out what you are doing.

In conditions of poor visibility the autopilot greatly helps avoid the disorientation you would otherwise experience when manual steering. The only other way to avoid this is to keep eyes constantly locked on the compass or rolling road display of your marine electronics. Knowing that your heading is being maintained to the desired course by the autopilot will greatly assist your own workload, providing more time to maintain a good lookout visually and on the radar.

Convenience

Reaching open water and being able to set the autopilot to hold a course or follow your navigation track frees you from rigidly holding the wheel and enables you to enjoy the day more. You must, of course, keep a good watch at all times, but being able to step away from the helm is a bonus on any boat and for slower cruisers, it can make a long passage considerably easier.

Taking that a step further, you'll probably find that the convenience of steering with buttons, a rotary control or joystick is so much easier, that you spend much of your time on autopilot.

Even for faster passages, it's nice for the crew to have a toilet break and pause for drinks and snacks. Rather than stopping the boat altogether and letting it wallow in any waves, you can reduce speed to just a few knots, placing the boat on a comfortable heading in relation to the sea and pop the autopilot on to look after things. The break in the journey will be appreciated by all aboard.

Efficiency

It's not unusual to see someone who is hand steering wander either side of the desired course. The reasons for this include inattention, fatigue, a tendency that some people have to over-correct, or even directional instability in your boat.

This can add considerably to the distance traveled through the water. Excessive helm corrections also add drag. An autopilot that is calibrated correctly will steer an efficient course, which will save fuel.

If the boat is doing the steering, then you can also pay more attention to trim and stabilisation if fitted, to optimise those also for the perfect cruise configuration.

Short-handed boating

If you do your boating alone or have crew of limited capability, an autopilot really comes into its own. As soon as you reach a safe area of water you can leave the engines in idle ahead with the boat on autopilot to clear lines and fenders away, ensuring of course to keep a careful eye around you.

Once out at sea, the autopilot is like a second crew member, reducing your fatigue and freeing time to keep the boat safe and sound.

What your autopilot can do for You.

Understanding the basics and the importance of calibration

Press the button and head for home.
For many of us, the fundamental purpose of an autopilot is to make life easier once we’ve had our fun. Yet, modern pilots are capable of a great deal more, especially when the going gets tough.

With a simple multifunction display and a handful of buttons forming the user interface, on the face of it, today’s autopilots don’t appear to have changed that much over the years. Yet under the skin, they are far more advanced and capable of much more than merely steering a straight course in flat water.

Communication systems have seen significant advances with more advanced ways of distributing signals between sensors and processors which has helped to improve performance.

“For many people, an autopilot is for doing the boring bit - steering straight - which is, of course, a big benefit. But one of the most useful functions is the ability to correct the heading so that the boat doesn’t drift off course,” explains Simrad® product expert Tonnes Haavarsen.

“In other words, imagine motoring across a wide river where the water is flowing across your path. The no-drift function allows you to get to the point where you want to arrive on the other side of the river without being swept off track. Here, the pilot would steer a straight line over the ground, compensating for any flow across your track. This is particularly important if you need to avoid being swept into shallow areas or towards rocks or moorings.”

From holding an accurate heading in awkward sea states, to no-drift functions, along with automated steering patterns that will perform a series of precise manoeuvres, today’s autopilots can provide the electronic equivalent of an extra pair of hands.

But to get the best out of these functions means making sure the basics are in place and understanding a few of the key aspects as to how autopilots work.

“From a user’s point of view, the most obvious changes are that displays have got smaller and the screens are now colour,” explains Product Manager Eirik Hovland. “Interestingly, the commonly used algorithms were developed quite a while ago and have stood the test of time in some harsh conditions. But it is the compass and sensor side that has changed the most. For example, whereas in the past we would have used a magnetic compass, now we use solid state sensors and in some cases a GPS compass.

“With better displays and more integration, it is easier to visualise your situation and your surroundings which allows you to make better use of some of the autopilot functions,” says Eirik. “Behind the scenes, there have been improvements in pumps and power consumption as well. It’s similar to what has been going on in our cars. We see little of what happens under the bonnet, and the fundamental process of driving remains the same, but there are clear advances in the way that they handle and perform.

“However, in a car, all the instruments are connected, calibrated and ready to go. Apart from syncing your phone, you wouldn’t expect to have to set anything up. In a boat it’s different.

“While many builders are very good at making sure that systems are calibrated and configured correctly, it’s not a given for an owner that this will be the case. Calibrating the core instruments is an essential starting point on any boat, big or small, sail or power.”

The bottom line is clear, modern electronics can offer significant benefits, but the advantages are difficult to make use of if the pilot and compass are not set up correctly from the start. So, getting the best out of your autopilot begins with understanding a little more about how the system works, what it requires from you and most importantly, how to set it up correctly.

Calibration is the key

“Poor or non-existent calibration is a common problem,” says Eirik. “We see a lot of autopilots that are badly tuned, but we also come across a wide range of expectations on the part of the owners. Some are happy if the pilot is steering the boat roughly to where they want to go, while others want the accuracy of plus or minus half a degree.”

Understandably, the specific level of accuracy that is required will vary depending on what you are using their pilots for, but whichever end of the scale you’re on, the principle comes down to the same thing. Calibrating the compass is the essential starting point, whatever level of accuracy you are after.

Calibrating the compass

“It’s important to make sure that the compass isn’t near a large metallic object such as the engine plus, it is better is the compass is mounted close to the centre of the boat,” says Eirik. “Make sure there are no metal objects near the compass itself. We’ve flown engineers a long way to sort out a problem, only to discover a toolbox next to the compass!”

Compass calibration is straightforward nowadays. The manual will explain how to set up the auto calibration mode, but essentially the process merely involves turning the boat through a couple of circles at a constant rate. This will cancel out any magnetic field anomalies.

Does your autopilot need adjusting beyond calibration?

First, find out whether the pilot steers straight. You need to know this over a range of speeds, especially for planing boats that may change their characteristics with speed.

“If the boat has trouble keeping a constant heading check your steering system,” says Tonnes. “No amount of calibration adjustments will correct play in the steering system. For hydraulic systems, make sure that there are no air bubbles in the system. If it’s mechanical, ensure that there is no slack in the system.”

“It is essential to check the rudder feedback system too. Make sure there is no slack or play in this either, as this will affect the information relayed back to the autopilot.

“It is also worth noting how the feedback system has been mounted. Ideally, it should be at right angles to the rudder arm as this will give the best chance of linear feedback. In other words, each degree of rudder arm movement is measured as a degree on the feedback unit. That said that, if it is not fitted at right angles, the pilot will still be able to compensate and calibrate the feedback signals and match them to what the rudder arm is doing. Mounting it at right angles reduces the potential for errors or confusion.”

“Once the compass is calibrated, you can then calibrate the rudder sensor and then calibrating the autopilot parameters to take account of the hull dynamics’” says Eirik. “While these are the finer points of calibration that have in the past required a bit of experience to do accurately, fortunately with modern instruments there is an auto-calibration function for achieving this which makes the process far easier.”