Autopilots
Silent revolution of solo racing
The device for the control and management of the ship’s direction is something that no solo ocean sailor can do without.
Modern autopilots go far beyond simply maintaining a steady course. The current generation of these systems is not only steering the ship faster than most humans can, but is changing the way modern IMOCA 60s are being navigated and even designed.
Modern autopilot systems are now able to offer one of the biggest changes in a wide swath of nautical sport, both in regattas and in cruising.
Among the many reasons for this great leap forward is the ability to control complex movements on board, especially while sailing.
Understanding this motion in detail is the first but essential step in anticipating what the rudder motion will be.
In the past, compasses with fluxgate technology provided a means of motion detection, but by today’s standards and expectations they were far too inaccurate.
Until relatively recently, for an autopilot to feel the boat enough to keep a racing boat on precise heading required an expensive gyro compass that only professional campaigns could afford, such as the Vendée Globe or the Transat.
Today, accurate motion detection is much cheaper and more efficient, using sensors similar to those used in smartphones, detecting pitch, roll, and yaw, each on three different axes. These sophisticated motion sensors are now very common in many modern autopilots. Being able to monitor the boat’s attitude at any given time for any set of conditions allows software to learn how a particular boat performs.
Targeting the performance predictions of ship designers, modern autopilot systems do their best to achieve the performance goal. “I have been working with Madintec on the autopilot system on board my ship, the Initiatives Coeur,” said English skipper Sam Davies. “Madintec provides the autopilot systems to many of the Ultime-class multihulls, and among the various configurations available, there is one that steers the boat to maintain an apparent wind angle and speed that does things you wouldn’t even dream of if you were steering boat. Sometimes it is quite a violent journey ”.
“Definitely my autopilot cruises faster than me,” he continued. “When you’re sailing solo or two, there are times when you can’t trim the sails fast enough to keep up with the autopilot. The result is that you have to navigate in a different way, there is a new style of navigation to learn ”.
As ship speeds increase, so do apparent wind speeds, which in turn cause the apparent angle of the wind to advance further. Higher wind speeds and tighter angles are influencing headsail design.
In addition to this, since the skippers cannot trim their sails fast enough to match the new movements the autopilot is making to the boat, the sail design has also had to change to create sail shapes that can function properly. efficiently over a wider range of apparent wind angles without having to trim all the time.
“It is not a completely new style of sailing, but, in short, there are things to understand because we are going at speeds that these boats have not traveled before, especially when it comes to medium speeds. We are beginning to feel much more resistance to the advance of the boat so the setting of the sail is different. The speed differences are also greater. So when you start to take off with the foils, you start to accelerate quickly, which means you have to keep up. Sometimes you can’t, so your wing trim must be able to cope with this. ”
Changes in the way the patterns trim the sails have in turn meant subtle changes to the different deck designs and specifications to ensure they can keep their boats at their ideal performance. And also, as a consequence of all this, some of the main design features of the hull and submarine appendages have also changed.
The increasing number of ships in the IMOCA60 fleet that are capable of maintaining speeds in excess of 30 knots means that designers have been forced to balance the rudder blades in such a way as to prevent them from becoming dangerously oscillating at high speed. But this, in turn, makes them more difficult to handle manually at lower speeds where the tiller becomes much heavier. Not only does this mean that more robust and robust components and mounts are needed for the autopilot, it makes manual steering much more difficult.
The extraordinary development of the foils and the resulting increase in performance under certain conditions has also been an important factor. Such is the nature of this new development at the forefront of sport that there is no guide on how to do it.
Additionally, IMOCA60 design rules prevent foils from having flaps or aileron-type devices to help control the amount of lift as an airplane wing would. The rudders cannot have T-foils either, further restricting the amount of control available. The result is a wing that tries to make the boat fly, but with few controls to help it balance when it does.
