Peter Foerthmann - SELF-STEERING UNDER SAIL

Racing with a large crew

Start of the Vendée Globe in November 1992

Competitors in the Vendée Globe, the singlehanded non-stop sprint around the world which starts from Les Sables d’Olonne in France every four years, rely exclusively on electric autopilots. The race, which includes 50 and 60-foot classes, is viewed by autopilot manufacturers as the ultimate test; the harshest conditions are guaranteed and the use of windvane steering systems is virtually out of the question (see Ocean racing section). Some older, slower vessels in the BOC Race (singlehanded around the world in stages) carry windvane steering systems as back-up, but here too autopilots do most of the steering.

60 ft ULDB Charente Maritime

ULDBs, which rarely have any kind of engine, rely on generators, solar cells or wind generators to maintain the power supply. The boats can reach speeds of 25 knots, so only the most powerful, ‘intelligent’ computerised systems are strong and fast enough to keep them on course. Autopilots are installed on every boat and steer most of the time. Although competitors in the long singlehanded races tend to follow a

10 minute waking/sleeping cycle, they never for one moment stop thinking about safety and boat speed. Nandor Fa lost about 12 kg in one Vendée Globe and knows only too well how the effects of this kind of deprivation endure.

Autohelm has a very big presence on the extreme sailing scene. The company has devoted particular attention to this area and has earned its success by maintaining a continuous presence before, during and after races, by making considerable service efforts and by cultivating its close relationship with the participants.

Windvane steering systems obtain their steering impulse from the apparent wind angle. The advantage of this is that a sailing boat likewise generates its drive from its position relative to the apparent wind. Once the sails and windvane have been set at the appropriate angle to the wind, the boat will continue to steer this angle indefinitely and the sails will always be properly trimmed.

Wind direction is the key consideration when planning any voyage. If the wind blows from astern it is possible to set the rhumb-line course and enjoy a comfortable trip from A to B via the shortest route. When the wind is on the nose, however, tacking is unavoidable and a compass course is useless; the direct route is not the quickest if the sails are backing.

The three elements of a windvane steering system are the windvane, the linkage and the rudder. We cover each in turn below:

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