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ELECTRIC AUTOPILOTS

With the advent of autopilots, it was felt that the demise of the older mechanical self steering systems was only a matter of time. But it is now apparent that is not to be; they both have their place.

Especially for ocean passages, you cannot beat the quiet simplicity and reliability of a good self steering system… the boat being powered by the wind and steered by the wind. The symmetry is compelling.

Windvanes Can Steer a Better Course

The wind never blows from a constant direction; it is always fluctuating and varying.

The best course for a boat under sail is to hold an angle fixed to the wind. A self steering windvane steers to the apparent wind and is therefore always in sync with sail trim. This means that the boat’s course meanders with the wind. It is not a straighter course, but over long distances is much more efficient and surprisingly faster.

An autopilot is clueless about the direction of the wind (unless set up with a wind sensor). It plods onward fixed to a magnetic course while the wind wanders freely.

On longer passages it’s impossible to constantly trim the sails and autopilots can suffer severely from that poor sail trim.

Power Consumption

We really do love our below deck autopilot too. It’s great for motoring and short hops, but that comfort changes when a few hours of usage becomes 24 X 7. The realities of offshore are very different. The power consumption of an electronic autopilot in big seas compounded over days is astronomical. Who wants to run the engine or generator 2 to 5 hours per day to keep the autopilot going? There is something the matter with that picture – running engines to keep sailing! This is when mechanical self-steering proves to be indispensable – it requires no power and the windier it gets the better it steers.

An energy neutral boat provides much piece of mind, if you can achieve it. When you take away the autopilot’s voracious need for power, especially when the going gets tough, a large responsibility is removed, replaced by a quiet confidence in the boat’s systems.

Autopilot Risk

Of course, the Achilles heel of electronic autopilots is the inevitability of break-downs. For a shorthanded crew the alternative of hand steering would be exhausting. Even if the autopilot itself never fails, failures of many other devices can stop the flow of electricity and, in turn, render an autopilot useless.

The probability of being without the autopilot, especially in bad conditions, is simply too great… and the resulting risk unacceptable.

Comfort at Sea

Another aspect that needs appreciating is that a more comfortable boat motion can be achieved with an auxiliary rudder self-steering system. When in use, the boat’s main rudder is locked in place and the auxiliary rudder takes over.

Nothing makes a boat more stable than a fixed main rudder. The bonus is that the main rudder’s fixing position compensates for any weather helm making the boat perfectly balanced and comfortably on course. The boat knows when it is holding course. And more readily returns to that ‘on course’ position when the Hydrovane is making course adjustments.

Cost

Why not invest one of those wind-sensor type autopilots that the racers use? Well the cost is big (double or up to quadruple conventional systems), reliability issues persist, and the power needs are such a tyranny. NKE in France led the way with a system that racers use. Brooks & Gatehouse now has such and perhaps Raymarine is competitive. Those are hydraulic systems with multiple boat and wind sensors that are fed to a computer that analyzes the data. To keep the systems going they need lots of power and for offshore you would still want to have a back-up system.

Ideal Set Up

If you can have both, that’s an ideal set up.

We love the ease of using a below deck autopilot for short hops. However, if the passage is longer than a few hours, the Hydrovane will be steering. When sailing offshore, the only time we use the electric autopilot is during a sail change.

And it doesn’t have to be a choice between a windvane or an autopilot. Consider adding a Hydrovane and then retrofitting with an inexpensive tillerpilot.

Servo Pendulum

History

After various efforts with trim tab systems, Blondie Hasler invented the servo pendulum windvane system in 1961. It was Nick Franklin who achieved the first successful commercialization of self steering with his Aries gear that was introduced in 1968, same year as the Hydrovane! Aries and Hydrovane were the first two windvanes on the market.

As of recently, Aries units are built in Holland. Similar systems have been produced for years by perhaps a dozen other companies. The main brands still produced today are Aries, Cape Horn, Monitor, Sailomat, South Pacific and Wind Pilot.

The Servo Pendulum Concept

A servo pendulum system pulls a line that moves the steering wheel or tiller enough to move the boat’s main rudder to bring the boat back on course.

Such a system includes a blade or paddle, called a servo blade (it is not a rudder). This blade swishes from side to side in the water, like a pendulum, directed by its windvane sensor.

As the boat falls off course the wind angle changes and the vane is pushed over. Movement of the vane rotates the in-water servo blade (also called paddle or oar). Once moved from dead ahead position, the flow of the water pushes the blade to one side with force. This movement pulls the connecting line to turn the wheel or tiller so the main rudder moves to bring the boat back on course.

Once on course the vane flops back to vertical/neutral and the servo blade reverts to trailing in the wake.

A servo system actually only pulls a line by about 10 in (25 cm), which is about enough to move the ships wheel a half a turn in each direction. Although they do not move the wheel by much (typical wheels have 3 revolutions, stop to stop) it is enough to do the job.

Comparison

The Hydrovane (an Auxiliary Rudder Windvane system) is very different mechanically and offers additional features than all servo systems, but a comparison is still possible.

Servo Auxiliary