Join Date: Jan 2000
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Selecting a Self-Steering Windvane
The Balearic Islands of Spain get very crowded in the summer, so July and August seemed like good months for a quick flight home to Canada from these distant cruising grounds. We enjoy these visits to catch up with family and friends, but this time we had another mission—to test-drive a new windvane self-steering system.
Paul and I were in the market for a new windvane to replace the one that had been stolen off our stern during Two-Step's last seasonal haulout. Our trusty Windpilot Pacific had been unbolted and removed in the dead of night while the boat was hauled out at a yard in southern Spain!
While we had managed without it during our spring cruise along the Spanish coast and through the Balearic Islands, we weren't prepared to continue further east in the fall without a windvane. We'd be making longer passages and facing stronger winds and seas and we had learned our lesson the hard way regarding the difference a windvane can make while cruising the western Mediterranean a few years ago.
On that cruise, we had been sailing with another boat similar in design to our Sparkman & Stephen's Classic 37, making a three-day passage from Estepona, Spain, to the island of Ibiza. We left with a good forecast, but in the course of the trip got hit with every type of wind the Med can throw at you. Our little autopilot couldn't handle the strong and sudden wind shifts and accompanying confused seas, so Paul and I spent most of the time at the helm and arrived cold, wet, disillusioned, and exhausted. On the other hand our friends—whose Aries windvane (no longer manufactured) handled the conditions with power and ease—were warm, relaxed, and raring to go exploring ashore. After that experience, Paul and I went shopping for a windvane.After lots of research and recommendations from the cruising community, we purchased a Windpilot Pacific servo-pendulum windvane that served us well for several years of transoceanic cruising. We were indeed heartbroken when it was stolen, but not surprised that it was the only one taken from the yard where there were many boats with windvanes bolted to their sterns. It's an excellent system and our thief apparently knew his or her stuff.
Paul and I were introduced to the new Voyager Windvane while conducting seminars at boat shows last winter we were been impressed with its quality and workmanship. Our trip home would be a good opportunity to try it out before making a decision to simply replace the system we had been using.
Before you go shopping for a windvane, know that not all windvanes work well on all boats. There are a few things you should keep in mind as guidelines for your purchase. First, consider the size and weight of your boat. For smaller and lighter boats, there are some simple, direct-acting gears available. If your boat is 35 feet or larger, a servo-pendulum model is about the only one that will be effective (the vast majority of vanes available today are in the servo-pendulum class). Next, consider rudder tiller configurations. Basic servo-pendulum steering gears work best when connected to a tiller. If you have a tiller, then this is probably the best option. If you have a wheel without much play in the linkage, you may be able to get good performance connecting the windvane lines to a drum on the wheel. But if you have hydraulic steering and if the wheel is a long way from where the vane will be mounted (as is the case with most center-cockpit boats) or if your wheel requires a lot of turns to alter course, then a windvane with an auxiliary rudder is about the only option.Other things to consider are the configuration of your transom, which may make mounting a windvane difficult depending on what else you carry on the transom. Both dinghy davits and booms that overhang the stern make windvanes difficult to install.
How Windvanes Work Windvanes are complicated pieces of gear (it certainly took me a while to figure them out!), so it is helpful to understand the different options and how (and why!) they work. Windvane self-steering systems, as their name suggests, get their primary drive from the wind. The vane, which is mounted at the stern of the boat, is designed to weathercock into the wind just like a traditional weather vane that you see on a rooftop. (In the case of a sailboat, the vane faces into the apparent wind.) Before engaging a windvane, the helmsman sets the boat on the course he or she wants to travel and then trims the sails to balance the helm. He or she then feathers the vane into the wind and engages the system. As long as the wind direction doesn't shift drastically, the boat will remain on course if the vane remains facing into the wind. When the boat moves off course, wind pressure is exerted on one side or the other of the vane causing it to move. This pressure and movement is then translated into a rudder correction that brings the vane back into the wind and the boat back on course. Note that it is important to keep an eye on the compass course when using a windvane self-steering system since it will follow any changes in wind direction. This is a big plus when trying to beat to windward, but a potential problem if a course change puts the boat in danger.
Windvane Types One of the earliest designs of windvane is the direct-acting vertical windvane. It consists of a large vane mounted on a vertical axis or post at the stern of the boat. A drum is mounted on a post around which a line is turned. This line runs directly to the tiller. If the boat goes off course, wind pressure acts on one side of the vane causing it to pivot. This turns the drum, which pulls the line, which moves the tiller, which applies rudder correction, which brings the boat back onto the desired course, and the vane back into the apparent wind.
The problem with this early design of windvane is that, in order to have enough power to effectively move the tiller, the vane has to be very large and heavy. Although these vanes are not commonly available any more, I mention this basic design because it is what got the whole ball rolling in windvane self-steering design and I found that after I understood the theoryof this simple, direct-acting vertical vane, it was easier to understand the more effective and sophisticated systems that have evolved from it.
To increase the steering power of windvane self-steering systems, the real breakthrough in windvane design was to make use of the force of the water and add it to the power of the wind to drive them using what is called a servo-pendulum rudder.Picture a paddle hanging down in the water beneath the vane and you've got the concept of the servo-pendulum rudder. It is actually a steering oar for the vane; it is not an auxiliary rudder to steer the boat. This confused me for the longest time! (Yes, there are windvanes that do have auxiliary rudders, see next paragraph.) The servo-pendulum design relies on the boat's own rudder to actually steer a course. Once I realized this, it made a whole lot more sense to me!
The pendulum rudder, or servo blade, is attached below the vane so that the blade can swing from side to side. When the boat deviates from its course, the wind now comes from a different relative direction and this causes the vane to flop over to one side. This is transmitted to the pendulum rudder by a linkage that steers the blade, turning it on a vertical axis. Imagine dragging the paddle of a canoe in the water. If you twist it on an angle, the flow of water over it forces it away from you or towards you, depending which way you turn it. So it is with the pendulum rudder; the change of angle caused by the movement of the vane then makes the servo blade swing to port or starboard. Lines are attached to the blade that run to the tiller or wheel and the blade's movement to port or starboard move these lines, which moves the tiller or wheel producing a course adjustment via the boat's own rudder.
The beauty of the servo-pendulum design is that the faster the boat goes, the greater the force of water acting on the blade and the more powerful it becomes. In fact, the power is so immense that you could do serious damage to yourself if you were to try to grab the tiller or wheel and manually override the windvane, so it's important when choosing one for your boat that it has a good mechanism to quickly disengage it in an emergency.
|"The beauty of the servo-pendulum design is that the faster the boat goes, the greater the force of water acting on the blade and the more powerful it becomes."|
If your boat has hydraulic steering, a center cockpit or a wheel with lots of play in the linkage, then a standard servo-pendulum system will not work. The answer is to add a second steering rudder to the boat that is connected directly to the windvane unit. Not only does this eliminate problems connecting to the boat's steering system, but it also adds stability and tracking—and at the same time provides a backup rudder in case the ship's mainsteering is lost. Of course the extra rudder adds weight and expense, but it may be worth it in the long run.
Using this system is somewhat different from a standard servo pendulum. First, the sails are balanced and then the ship's main rudder is set to hold the course and locked in position. Then the vane is engaged and governs the auxiliary rudder, which then takes over steering the boat.Test-Drive After testing out the Voyager, we were very happy with its performance as demonstrated on the Niagara 35 owned by the designer and manufacturer, Peter Tietz, a skilled tool and dye maker and experienced offshore sailor. We also liked his extensive use of stainless steel parts and think it more effective at reducing corrosion than the aluminum used in other models. But the hull configuration of our Classic 37 is quite different because of its narrow beam and full keel with a keel-hung rudder. We needed to talk to a Voyager owner with a similar boat. The Alberg 37 is almost identical to ours and one owner we found was happy to help us. For us, the final deciding factor was price. Voyager is manufactured in Canada, so the exchange on the US dollar is excellent. The price for our wheel-steering unit was $2900, and it's less for a tiller system.
Having a servo-pendulum windvane on our 37-foot sloop greatly improved our boat's performance as well as our comfort and well-being at sea. If you are planning some long-distance cruising in the future, it pays to start researching this important piece of gear now. Talk to as many owners as you can about the various options and if you can organize a test sail on a similar boat to your own all the better. You won't be sorry.