Autopilots and Windvanes - SailNet Community
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Autopilots and Windvanes

This article was originally published on SailNet in July 2001.

Autopilots and windvanes afford their crews the ultimate freedom—the freedom to do something else while the boat steers itself.

Ask long-distance sailors what piece of boating equipment they value most and odds are they'll all say their self-steering gear. Whether it's an electronically powered autopilot or a wind-driven windvane, a reliable self-steering system works as a tireless, extra crewmember. It can steer while the regular crew attends to navigation, sail trim, or the many other tasks required in the safe operation of a sailing a boat at sea. These devices mind the helm when the weather is foul, so the crew on watch can stay sheltered and dry, often preventing injury and illness. Since they reduce effort, the crew has more energy, is generally happier, leading to a relaxed frame of mind that fosters better decisions, thereby improving safety. But the best thing, some will say, is that unlike "real" crew, an autopilot or windvane never complains!

Well, this isn't always the case. On our first Atlantic Circle from 1989 to 1992, we used only an electronically driven system that complained a lot. In all fairness, the Autohelm 3000 we purchased was not designed for our size of boat. A larger built-in autopilot would have been more appropriate for our 37-foot home.

But when we set out on our first adventure we were only planning a one-year sabbatical of island-hopping in the Caribbean. We were on a budget and it was cheaper to buy two identical autopilots (one for parts) than the $3,000 windvane system that we lusted after. Our dream was that, at the completion of our voyage, the second autopilot would still be in its box, shrink-wrapped and untouched, ready for resale. However, that was not to be. We used all the parts in the second unit and even rebuilt a few, but those two little Autohelm 3000s ended up steering us 19,000 miles in what turned out to be a three-year voyage to 23 countries around the Atlantic. They soldiered through the worst Atlantic storm we've seen in 11 years of cruising, for which I am eternally grateful.

On our next transatlantic passage in 1997, we added a windvane system, which is now the primary self-steering gear on Two-Step. But we still use our Autohelm 3000 when the wind is light.

Autopilots can steer a straight course if they're properly sized and if there's an ample supply of electricity to drive them.
Autopilot Pros and Cons   
Electro-mechanical autopilots, as opposed to wind-powered self-steering vanes, are appealing to sailors for many reasons. Autopilots are generally more affordable, they are lightweight and install cleanly in the cockpit or invisibly below-decks. The steering impulse for autopilots is a compass heading, so by design they are good at holding a course. A wind shift does not affect the heading they're steering the way it does a windvane. They are also easy to operate—punch a few buttons and you're on your way!

However, they do draw power, which is always a major concern on a long offshore passage. When the wind and seas are up, so is the effort at the helm and that effort translates into more amps drawn from the batteries. Some autopilots draw three amps or more almost continuously in a heavy sea. They handle well in big seas except when the wind is from astern; then the boat tends to yaw and broaching is a big worry. We've found that our autopilot just doesn't react quickly enough to a slew. Sometimes on that first trip I would wake up while off watch and hear Paul shouting at the autopilot, “Turn you idiot. Turn!” (I think that's why it always chose to break down in the middle of the darkest nights—revenge!)

I also find the constant drone of the autopilot's motor tiresome, but on hot windless days at sea it's very easy to forgive this behavior. Our autopilot steers us faithfully onward to our destination when the windvane lags.

Windvanes take advantage of the same forces that propel the boat, although care needs to be taken when it comes to windshifts, especially if running before the wind.
Pros and Cons of Windvanes    
When we installed a windvane self-steering gear on Two-Step in 1997, it changed our cruising life. Our Windpilot, a German-designed system widely used in the international cruising community, eliminated the worries of battery drain and midnight repairs to the autopilot. Its powerful paddle counteracts any yawing and as a result Two-Step's motion and performance are greatly improved on passages. Windvanes are big and strong but, because of this, they are often heavy and cumbersome on the transom. They also require lines running to the tiller or wheel (in our case), which clutter the deck or cockpit, but it's worth it! Yes, these items can be expensive, but we now feel that the comfort and safety a windvane system provides well offsets the cost.

I also enjoy the sense of harmony these devices can bring to a boat. The drive of a sailboat is generated by the position of the boat and the orientation of the sails to the wind. It is the same with a windvane. Set both to the apparent wind and drive is assured. Both the sails and the windvane then work together quietly, in tune with your surroundings, getting you where you want to go. Except, of course, if there isn't any wind.

Paul demonstrates that on a tradewind passage hundreds of miles can pass with minimal time spent on the helm.
If your budget allows, we have found that a combination of a windvane and autopilot self-steering system is the ideal solution for long-term cruising. You are then covered in all conditions and have a backup system if one or the other breaks down. On a recent cruise along the Costa del Sol, our Windpilot was stolen so at this moment we're installing a new windvane—this time a Voyager windvane, designed and manufactured in Canada.

In our book, Sail Away! A Guide to Outfitting and Provisioning for Cruising, and our video, Transatlantic Crossing, Paul demonstrates how windvanes are driven by the power of the wind and the flow of water past the yacht. Some understanding of the physics involved is necessary to operate windvanes successfully—no easy pushing of buttons here. Now that is unfortunately a deterrent to some sailors, but I actually found it to be an advantage of sorts. On our first few passages using the windvane, I never grew tired or bored on watch. I was too preoccupied playing with the thing and trying to figure out just how the heck it was steering the boat!

Suggested Reading:

Selecting a Self-Steering Vane by Paul and Sheryl Shard

Autopilot Overview by Tom Wood

The Cruising Cockpit by Sue and Larry

SailNet Store Section: Tiller Pilots

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