Jessica Watson: Ella's Pink Lady uses Fleming windvane self steering system

The need for self-steering is well understood by passage makers, ocean racers and other blue water sailors. 

While some elect to use an electrically driven autopilot for this function, many long distance voyagers have opted for the rugged simplicity of a windvane steering system – which uses no scarce electrical resources.

Jessica Watson has equipped Ella’s Pink Lady with the Global Equipe 400 from Fleming Marine in Blairgowrie, Victoria, Australia.

This particular model is a servo pendulum type that moves the rudder of her S&S 34 through the use of control lines. 

In use, the vane is set for the specific point of sail to be maintained. Once this is done, the vane sensor is set and the vane gear is engaged to maintain course.

Unlike an autopilot, which will maintain a specific compass course or track to a specific GPS waypoint, the windvane system maintains a specific angle to the relative wind. If the wind changes direction, the boat will steer to maintain the same position relative to the wind – but will change compass course.

In a vast ocean space – with a single crewmember – drifting of compass course a bit is preferable to an accident gybe or backing of sails. On a practical basis, the wind does not quickly change direction on the open ocean like it may in coastal areas and this apparent disadvantage of a windvane system actually results in small variances that can be tolerated.

When the vane is initially set, both faces of the vane have equal pressure on them – it is stabilized or streamlined to the relative wind. With a change in the relative wind – caused by a slight boat heading change – one side of the windvane will get more pressure than the other. This will tilt the vane which is connected mechanically to a servo “oar”. This type of design greatly increases the force of the signals from the vane.

As the vane is moved it moves the servo oar. The oar gets forced by the slipstream of the water to swing to one or the other side of the hull. Through the pendulum oar a very powerful leverage is created which is used to turn the main rudder through an on-deck linkage with lines and blocks.

This type of system is becoming the most popular in use today since it is more responsive to light air conditions (down to 2 knots boat speed), uses the boat’s own rudder for steering, is very responsive in higher wind conditions is easy to maintain and repair  and minimizes the yawing effects of the boat moving downwind by automatic counteraction to prevent broaching.

Ilustration courtesy of selfsteer.com