A mechanical autopilot
The windvane steering system is an entirely mechanical autopilot, used before the arrival of electronics. It keeps the boat's course relative to the apparent wind angle, not the compass heading. Thus, the course changes with each change in wind direction.
Before its mass production, many boaters built it with their own hands. Francis Chichester used it in 1967 on his Gipsy Moth IV, and the following year, the competitors of the Golden Globe Race - the first non-stop round-the-world sailing race - also used it.
The two types of speed controllers
There are two types of flow controllers:
- Auxiliary rudder controller (hydrovane type)
With this type of rudder, the boat's rudder must be immobilized. A scoop in the water, serving as an auxiliary rudder, takes over from the main rudder (since the helm is neutral). On deck, a blade on the transom is set at a given wind angle. The boat then follows its course while maintaining its speed relative to the wind. As soon as there is a wind rotation, the aerial blade moves to adapt, which causes the submerged blade to rotate around a vertical axis (like a conventional rudder). The sailboat will either luff or luff down in order to regain the correct point of sail.
- Servo-pendulum controller (Atoms type)
This type of rudder acts directly on the boat's helm. It uses the boat's main rudder, whose action it retains. An overhead blade is set at the desired angle for the boat's desired point of sail. Mounted on an axis, it tilts according to the wind's rotation, while being braked by a submerged shovel to which it is connected. The overall rotation of the system around a horizontal axis drives the boat's main steering system through a system of ropes and pulleys.
Advantages and limitations
The main advantage of the windvane gear is that it uses only the force of the wind and water. It does not require any electrical power. This makes it the ideal ally for boaters on long voyages on small sailboats or in search of energy savings.
On the other hand, they are more exposed and can be damaged in case of strong wind or collision with UFO.
The windvane steering system only works in relation to the apparent wind. It therefore requires a well-balanced boat. Its strong point is upwind sailing. With a strong apparent wind, the boat generally reacts very well and follows its course perfectly. It is preferable to have a tiller, especially for the servo-pendulum rudder, as it will work better.
However, another limitation of the windvane gear is the absence of wind. In flat calm, it cannot work and in light and variable winds, it is not reliable. It is better to steer by hand. Downwind, it is also more difficult to stabilize and will work better on displacement hulls than on planing hulls.
