Autopilot technology steers Vendee Globe leaders right
Sailing fans around the world are 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... READ FULL ARTICLE