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Wind vanes refined

Oct 24, 2013

Newest developments in wind vane self-steering technology

A Hydrovane airvane-controlled auxiliary rudder unit on an Ovni 385.

A Hydrovane airvane-controlled auxiliary rudder unit on an Ovni 385.

Courtesy Hydrovane

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If you think wind vane self-steering rigs are on their way out, think again. The biggest producers of these mechanical wonders continue to refine their products into sleeker, lighter, more effective vane gears that keep this energy-saving technology a must-have among offshore cruising vessels.

Servo-pendulums, comprising the majority of vane steering systems, plus trim tabs and airvane-powered auxiliary rudders, continue to prove their worth over thousands of miles of cruising in the lightest airs to the most severe sustained gales. Some vane gears tend to work better in stronger winds, while other systems seem to be better suited to the vagaries of light, shifting breezes.

Yet one thing is certain: all of these wind-powered steering systems can be trusted to last a long time and be a reliable, electricity-free form of self steering.

Courtesy Scanmar

A swing gate Monitor unit on a vessel is strong enough for crewmembers to sit on when open.

Wind vane steering systems
To re-cap briefly what we may have learned about wind vane self-steering, these devices fall under three categories: servo-pendulums, trim tabs and airvane-powered auxiliary rudders.

The typical servo-pendulum system combines the forces of both wind and water to control the vessel’s rudder via double-braided control lines. As the vessel sails toward or away from the wind, an airvane dips to one side, activating a push rod that turns one side of the servo blade against the rush of oncoming water. The servo blade immediately swings to one side, pulling the tiller or turning the wheel until the airvane is standing straight and the vessel is on course.

It is actually much simpler than it sounds and even simpler to deploy and maintain. Our 1966 Cal 30 Saltaire completed a circumnavigation by way of two canals with a Fleming Global 301 servo-pendulum, requiring only the occasional changing of frayed steering lines and broken airvanes, which I cut from thin pieces of plywood. Through every kind of weather, from light airs to sustained gales, the airvane faithfully bowed under the wind, pressing the push rod and commanding the tiller at the precise moment the vane sensed a change of course.

During a sustained mid-Atlantic winter gale, the vane gear kept Saltaire surfing straight down 25-foot combined seas with nary a worry about broaching and capsizing.

Courtesy Scanmar

Scanmar’s Monitor servo pendulum  model can be installed with swing gate mount to access the stern.

One over-arching advantage of servo-pendulum technology, aside from yaw prevention, is their adaptability to steer virtually any size of oceangoing yacht. The Navik, built by Plastimo in France, weighs a mere 30 pounds and would be perfect for anything from a Catalina 22 to a Baba 30. At the other end of the spectrum, the Windpilot Pacific Plus II can be fitted to a vessel up to 60 feet LOA.

A trim tab system comprises a narrow foil, like an elevator on an airplane, usually connected to an auxiliary rudder. While trim tabs operate in virtually all kinds of navigable weather, they are more at home in light airs where a servo-pendulum may not be able to draw sufficient steering power from slow-moving water. Don’t be fooled, though, by their seemingly delicate construction and operation. Trim tab systems, even homemade versions, have finished many circumnavigations and continue to draw a large following among seasoned offshore sailors.

Finally, the airvane-powered auxiliary rudder uses small reduction gears to convert air force directly into steering power. This type of unit, available exclusively from Hydrovane, is completely self-contained and operates in anything from a light zephyr to a sustained force 9 gale.

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Sep 14, 2014 07:05 am
 Posted by  brunos


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