Autopilot technology steers Vendee Globe leaders right
Sailing fans around the world have been marvelling the blistering performance of the Vendee Globe leading pair, Armel Le Cléac'h, Alex Thomson, whose state of the art foiling IMOCA 60s have been shattering race record since they left Les Sables D’Olonnes almost five weeks ago.
The pace of the French and British skippers has been relentless and has earned them a lead of over a thousand nautical miles on the chasing pack. Both averaged more than 20 knots through the Atlantic between the start and the Cape of Good Hope and there has been no let up since.
A large part of these remarkable performances can be attributed to the boats’ new foil systems, but spare a though also for the hardworking autopilot systems that enable the skippers to keep the hammer down day and night – even while they snatch a fitful 40 winks.
According to Alan Davis, product line director at B&G, whose company designed and built the autopilots for all the new boats in this edition (including Le Cléac'h’s Banque Populaire and Thomson’s Hugo Boss), typically in the Vendee Globe it is the autopilot rather than the skipper that steers 95 per cent or more of the time.
“Generally those that are comfortable driving the boats hard on autopilot are the successful ones. You can’t drive fast 24/7, so investing time in autopilot performance is wise. Francois Gabart said after the 2012 race said something along the lines of ‘the autopilot steers unless I need a little fun’.”
Alex Thomson Sailing team member, Neal McDonald, explains the basic setup of a Vendee Globe grade autopilot system.
“In its simplest terms, there is a pilot controller and a ram that moves some sort of tiller arm that in turn moves the rudder. The clever part is the brain that takes in information from various sensors reading things like heading, heel angle, rudder angle, yaw rate, boat speed, and information from the wind gear at the top of the mast, and uses it all to steer the boat to whatever criteria the skipper asks for – for instance, a compass course, a specific true wind angle (TWA) or an average wind angle (AWA).
“Aside from that basic functionality the H5000 system that Alex is using also has plenty of sophisticated ‘add-ons’. Some of these features try to mimic the way we would steer a race boat. Some of them focus on safely dealing with gusts and wind changes – for instance, bearing away automatically in a gust when going downwind. Others may try and minimize the amount of energy being used to sail the boat. I have little doubt that Alex will be endlessly playing with these as conditions change.”
Davis agrees with McDonald and says B&G have made some significant adjustments to what they call the Expert Systems within their autopilot.
“These systems sit on top of the core steering algorithms and make strategic choices just like a human helm – for example if the wind increases by 20 per cent while reaching, the autopilot can automatically widen the target wind angle to keep the boat flat and fast, maybe also preventing a broach. These systems are continuously improved with feedback from the leading race teams and the amateur short-handed sailors.”
The requirement from Vendee Globe skippers for an autopilot to keep them both on course and upright when travelling at speeds up to 30 knots plus has resulted in highly refined hardware and systems that take data from a dazzling array of sources.
“The B&G Pilot has changed to a new hardware platform with significantly more processing power, allowing us to carry out internal calculations faster and more often, which provides more confidence in the received data and allows us to push the boundaries a little more.
According to Charles Darbyshire, a solo offshore systems expert and managing director at Fourth Cape, a good wind solution is vital for consistent performance in the Vendee Globe.
“You will see large masthead wands located vertically as high as possible away from the up-wash from the mainsail,” Darbyshire explained. “Then you need a motion sensor to calculate out the motion of the mast head, coupled with a fast and accurate compass. To give you a good approximation of the wind, the system has to do these calculations many times per second.
“When a pilot is well set up and ‘enjoying’ the conditions, it’s a real pleasure to watch either the tiller move on deck or down below as the ram jigs in and out. Conversely, when the autopilot is struggling with the waves or shifty winds, it can be very draining for the solo skipper struggling to deal with it.”
Although it would seem logical that the advent of foils must have made life harder to cope with for IMOCA 60 autopilots McDonald and Davis both believe this is not necessarily the case.
“Strangely enough, I imagine that in some conditions, foiling has made it easier for the autopilot to control this generation of boats,” McDonald said. “For sure on Hugo Boss the foil provides an element of dynamic stability that often smooths out the effects of gusts.
“What it feels like is that the boat accelerates in the gust and that extra speed increases the righting moment generated by the foil, so reducing the additional heel from the gust. This appears to make the autopilots job slightly easier in some conditions. Having said that, in really wild conditions I can only believe that the boats will need much more taming and trimming the variables on the autopilot will be a big part of how to do that.
“Much of this capability is likely down to enhancements made to the autopilot system software, but there have also been improvements made to the external sensors that provide the data input. For example, Hugo Boss has a very sophisticated compass that gives incredibly accurate heading information.
“The speedos have also improved too and Alex has one fitted in the bulb so that the paddle wheel does not keep popping out of the water.”
Davis too has found the transition between displacement sailing to being foil assisted less significant than he expected.
“The additional speed puts a premium on autopilot performance generally - if your autopilot isn’t stable at 15 knots then it is unlikely to be any better at 25 knots – but apart from that there appears to be little change.
“The use of B&G Pilots over the last decade on the large multihulls like IDEC and Sodebo have previously extended the performance range of our pilot, so the new generation of foiling 60s was already within the performance range we had been working with.
“The higher speeds have pushed us to tweak the High-Wind Response and Recovery modes as these are more significant now than previously. The next challenge will be stable, autopilot-controlled, fully-foiling multihulls like the Multi70 Maserati. [Ed note: previously a MOD 70 converted to foiling and developed by Seb Josse’s Gitana sailing team. Now skippered by Italian Giovanni Soldini]
The unrelenting demands of the Vendee Globe are a punishing proving ground for all on-board systems but none more so than the autopilots. No surprise that they bristle with fail safe devices and feature plenty of built in redundancy.
“The pilot is like your uncomplaining co-skipper, but there are plenty of potential points of failure,” Darbyshire explained.
“Lose your wind gear from the mast head and you lose a whole mode in the pilot. Lose power on board and you lose your pilot completely. A ram failure means your steering ‘muscle’ is gone. Even a problem with the cheapest main component, the rudder reference unit, means the pilot loses its ‘feel’ when it steers.”
As Davis explained, the latest generation B&G pilots being used by Thomson and Le Cléac'h this time around, have automated failsafe sources for key data. “Heading sensor number one failed? Automatically move to heading sensor number two and let the skipper know what you did. Previously that would have been a klaxon, a broach and potentially a race ending failure.”
McDonald confirmed Thomson’s boat has plenty of redundancies built into the autopilot system. “Alex also has two complete systems permanently connected and a complete separate unit in his spares. He has sailed around the world countless times with this type of set up so he and the team know this system inside out.”
Spend any time watching the videos being sent back from the two leading boats so far and you quickly appreciate how hostile the on-deck conditions are when they are travelling at speed.
No wonder then that the skippers stay tucked up inside as much as possible and trust their uncomplaining autopilots to keep them blasting along the right track.
[Additional input and understanding for this article was supplied by Ryan Breymaier of breymaiersailing.com]