Staying In Charge—Part II, Wind Generators

Wind – 24 hour power

In recent years, with more people going ‘off-grid’ in yachts, RV’s and remote cabins, micro wind generation has come a long way, largely through the adoption of new materials and technologies such as neodymium permanent magnets. Some of the latest generation of wind turbines can produce really acceptable amounts of output around the clock in the right circumstances. But there are still limitations:

• A wind generator needs reliable, clean wind to function properly – a rare commodity in sheltered harbours or anchorages, or areas where the wind drops light at night.
• At sea, while they work well upwind, downwind they are weak.
• Most of the more powerful units don’t start producing appreciable amounts of output until average wind speeds exceed (at least) ten knots.
• Some of them are noisy and vibrate  – although this is, in general, an area that has seen great improvement.
• Many of the more potent units are heavy, requiring substantial brackets and leaving extra weight and windage where it’s least wanted – high above deck level.

What Are They Like to Live With?

Anyone thinking of installing a wind generator should assess:

• How much output can it produce?  If the model you’re looking at doesn’t produce substantial power in ideal conditions, is it worth having, either in terms of cost or nuisance value?
• How quiet and vibration free is it? If it isn’t, you’ll be turning it off (and everyone else near you) all of the time.
• How heavy is it relative to the size of your boat? The weight and windage of a really powerful unit might materially affect stability on a modest sized boat. Most yachts aren’t designed (like Pèlerin or the Adventure 40) with an arch and generator factored into their stability calculations.
• How safe is it, and can it be left unattended? Any generator should have not just an internal limiter to slow it down in high winds, but also a remote off switch.
• How reliable is it? Many models are virtually impossible to service or repair yourself.

Our Experience

When we were planning Pèlerin, we were determined that if we were going to have a wind generator, it would have to meet all of the above requirements. We eventually went for the Superwind, a three bladed turbine, with a 350W output, external regulator and on/off switch.

Apart from being slightly noisy with the original blades, it has performed faultlessly for nearly five years.

It delivers really healthy amounts of power above ten knots of wind quietly and without vibration, and is without doubt one of the best pieces of kit we have bought.

At 11.5kg it requires a hefty mounting bracket, and at around US$3000 (generator, charge controller and off switch), it’s not a cheap unit, but it is very well engineered and if our experience is anything to go by, the cost spread over time is more than acceptable.

What Else Should Be Considered?

Charge Regulation

For any unit capable of delivering substantial amounts of amps, there should be some form of charge regulator and dump resistor for handling surplus output. On most units these are external and an additional cost, as may be an off switch. Some units such as the Kiss (300W) and the Air Breeze (200W) use internal regulation, saving cost and simplifying installation.

Vibration Damping

In order to dampen the vibration generated by some models that can be transmitted into the boat, additional means may be needed, commonly by means of mounting the base of the tube on a rubber gasket or block.

Many manufacturers specify stock tube for the mounting pole, which makes installation easier, but every aspect of the mounting bracket and its installation will need to be carefully designed in order to cope with the considerable loads generated in a seaway, especially for the heavier, more powerful units like the D400 (15kg).

All of the above will need to be taken into account when you price up your chosen unit.

Is It Worth Installing A Wind Generator?

Given that the model you choose meets the above criteria, if you spend time at sea or at anchor in areas where there are higher than average wind speeds, then a wind generator will be a real advantage.

The critical factor is estimating what you can expect in terms of amps per day. Peak outputs may sound impressive, but only tell part of the story. What really matters is what the unit can deliver in a wide range of conditions. Practical Sailor carried out a really useful trial (subscription required) a few years ago that should be required reading for anyone considering fitting a wind generator. Whilst we’ve seen days when our our Superwind has generated over 100 Ah, equally there have been many days when we’ve seen far less. Which is why, in my view, a wind generator should be best considered as part of an integrated supplementary power installation.

What Might Work Well On The Adventure 40?

While the Adventure 40 will not come standard with a wind generator, she will be set up with an arch and wiring conduits to make the installation of one easy. So, if your budget can run to it, and the weight is acceptable within the stability calculations, then the Superwind 350 would be a good choice.

If weight and budget are a constraint, then the Air Breeze has a lot to recommend it. Its predecessor, the Air X (400W) probably put more people off installing a wind generator than any other single thing due to the truly awful racket it made when operating, but the manufacturers have really got on top of that.  By reducing the rotor speed and modifying the blades, the new model is now (at least) tolerably quiet. Ultimate power output has been reduced as a result, although in tests it has still performed very well indeed. Light (5.9kg) and relatively inexpensive (US$1195 for the basic unit) and with internal regulation and an off switch, it would fit nicely on the arch of the Adventure 40.

Comments

Have you got experience of any of the above models? Let us know with a comment.

Further Reading

• Lots more on electricity on voyaging sailboats.