Almost as free as the wind

Well not quite, but wind generators supply a lot of power for a relatively low outlay, writes Jon Neeves.

Ask any owner who actually spends more than a couple of nights on their yacht as to what are the biggest headaches with liveaboard life and consistently they will comment on the inadequacies of electrical power.

Question a bit more and you quickly learn the power requirements of the modern yacht at sea are much greater than battery capacity even for short passages. You can, of course, run the engine but this partially defeats the basis of having a sailing yacht.

Established options

There are a number of established options. Buy a genset: like the main engine – noisy, but popular and getting cheaper with the introduction of units from China. Solar power: a good option except most monohulls simply do not have the space to locate many panels. Solar panels are modern – and thus sexy. Despite increased usage in urban applications solar panel prices do not seem to have fallen. Invest in a wind generator: pretty old and thus well established technology. They are small, quiet – but not really popular. There are more (and less well established) options: use a Stirling cycle engine or even give up those power-consuming items that most of us take for granted in the 21st century.

We have been using a wind generator for more than 10 years now (and a 350-watt solar power bank) and with a bit of care manage to live a fairly sybaritic life when at sea – but that is partially because we bought a hybrid wind generator, one that converts to a water generator. However, we could not survive, electrically, using the wind generator alone because, like everyone else, we choose anchorages for their lack of wind which means we need that fall back of the solars. But when our wind/water generator has the chance, it piles in power (in water mode eight amps at eight knots boat speed) – and we would not be without one. Our positive experience of wind generators is not unique – many yachts have two units, and they are not that cheap so others must also find them effective.

It’s odd wind generators have not caught on for yacht owners. Fly into Heathrow from the east and the Thames is full of wind generators. So why do yacht owners not more widely embrace the wind generator?

Lower sun levels

Simplistically wind generators would be the choice for locations with lower sun levels (and stronger winds) such as Tasmania. Looking in slightly more detail, those areas with consistent trade winds would also be advantageous for wind generators – and these are not necessarily areas of low sunlight. One significant advantage of wind generators is that they work 24 hours and times of darkness are times when power usage is higher. Not many of us watch DVDs or switch on anchor lights during the daytime. There is a balance, and it probably favours both solar and wind or wind/water power.

Power requirements

Before looking at the choice of wind generators available what are the power requirements of the average yacht? If you keep your yacht in a marina, you should have full access to shore power, enabling your batteries to always be fully charged. Even a yacht on a swing mooring can maintain full battery levels with even a small solar panel. Moving off for a two-night weekend your power requirements will be fairly low, the fridge and (tungsten) anchor light (unless you are one of the selfish minority who do not use an anchor light) being the major requirements. You might sail to reach your chosen destination but engine usage coming into the anchorage will top up the batteries. If you have a newer yacht, your anchor and interior lights will all be LEDs, your DVD player charged prior to the weekend, and it’s really only the fridge that will consume power. A decent house battery bank will cater for that.

It is when a yacht is used continuously away from a shore environment that power really becomes an issue, and the limited numbers of people able to enjoy this usage of their yacht is one factor why wind generators are not more common.

But once away from shore power on board electricity is a real issue. Autopilots, chartplotters, navigation and anchor lights, fridge, radar, DVD players, mobile phones, VHF, laptop etc – none are a major issue in themselves, and none by themselves extraordinary, but added together they constitute a huge power requirement. If you want to cruise for more than a few days and you want to enjoy today’s “benefits” then you will need some means to generate power. The wind generator is just part of the powergenerating equation.

So what are the choices?

Fan-bladed wind generators

Fan-bladed wind generators, and obscure though it might seem these can be divided into those with an odd number of blades and those with an even number of blades.

Hybrid wind and water generator sets. (There are also ways to generate power solely with water, using the yacht’s propeller being one such option – these options are not covered here.)

Vertical axis turbine wind generators. These have a low power input. Think of trickle charge only. They will keep your batteries topped up but will not do much more.

To discuss the number of blades in a wind generator fan might seem odd. But sadly wind generator blades get broken, usually being hit by a loose sheet or halyard.

If you lose a blade from a wind generator with an odd number of blades, you have lost your power source. If you lose the blade of a fan with an even number of blades, you can simply remove the opposite blade to the one that is lost and the fan returns to balance. It might be less effective because four blades are obviously not going to be as powerful as six, but you will continue to produce power until the new blade arrives.

There is another issue: three-bladed fans tend to make more noise than six (or five) bladed fans. Whether this is a function of the longer blade length of the three-bladed fan or the fact the blades are slightly more flexible is unknown – and it’s purely a personal observation that the three-bladed fans are noisier. But noisy wind generators are a nuisance and can be very annoying, especially if they bladed fans tend to produce more power at lower wind speeds than three-bladed larger-diameter fans but conversely three-bladed fans produce more power at higher windspeeds.

Finally, the larger diameter of the three-bladed fans means they take up more space, maybe 25 percent more, and need to be located “further away” than a five or six-bladed fan.

Oddly wind generator commercialisation has been a British strength, until the introduction of the three-bladed designs. If you want a hybrid unit – they seem available only with British ancestry - the four major UK players are LVM (Low Voltage Motors) now owned by ITT, Ampair and more recently Eclectic Energy, all of whom produce “straight” wind generators and hybrid versions. The fourth supplier is Goodbridge Environmental, who supply the vertical axis Forgens (and a conventional fan unit). But there are lots of wind generator manufacturers – it is an old technology.

Where to put it

Wind generators need to be fairly high to enjoy clean air and keep the blades away from the crew and the higher they are the more wind they enjoy.

The obvious and most common location is as part of a scaffold arrangement on the transom also incorporating solar panels, davits for a dinghy and the location for various aerials, GPS, VHF etc. Wind generators are not particularly heavy, usually around 6-8kg, and the loads on them not much of an issue when at rest. At sea you soon realise they are waving around on a longish pole so the pylon needs to be pretty beefy and you might want to strengthen up the deck with some decent backing plates. An ideal location on a ketch, depending on the rig, is the mizzen mast. For multihulls, we had ours on the port transom, which worked well most of the time or at least until we were on starboard tack and then the main completely blanketed the wind generator. Our wind generator is now located in the middle of the bridgedeck transom well above coachroof height and set back from the boom.

Pylons

Location does need some thought because it needs to be out of the way of body parts but accessible (you might want to service it, stop it operating or use it in its water mode). You might also want to include the pylon in your costings – a decent pylon can cost $1000. Note that the most expensive unit, the Duo Gen, comes with its own tower – so it’s not quite as expensive as it seems.

As mentioned the Duo Gen is supplied with its own tower, which is also used when the unit is in water-generator mode. The Ampair and LVM units use a trailing impellor on a 15m rope as the drive unit with the “gen” set commonly suspended from or off the transom. The trailing impellor solution is a bit fiddly to assemble. It takes about 20 minutes (not the five minutes claimed in the promotional literature) to take the LVM unit off its pylon, remove the fan, attach the rope and fix the drive unit to the transom. Consequently one would only use the water mode option when at sea for a number of hours. Deployment of a trailing impellor is best done by deploying half the tow rope and then flinging the impellor wide – it works perfectly every time. Recovery needs the yacht virtually stopped, or certainly moving very slowly, because you need to overcome the drag and the impellor continues to turn (wear gloves). Trailing an impellor is obviously inconvenient if you want to trawl for mackerel. In fact, you cannot do both at the same time (unless you have a multihull).

Also multihulls can sail so fast that the impellor skips, at anything above about 10 knots. There are also stories, possibly apocryphal, of impellors being eaten by sharks. We have lost one blade, glass-reinforced plastic (probably hitting something in the water rather than a shark attack!). An impellor also introduces drag — maybe half a knot at six knots of boat speed.

To mitigate some of these disadvantages we have made smaller stainless blades which means the impellor can operate at higher speeds and is more robust. However, provided you are willing to accept these shortfalls a water generator will power most requirements of a cruising yacht making 6-7 knots.

Each of the makers of the hybrid units — Eclectic, LVM and Ampair — produces standalone wind generators, basically the same units but specifically designed for wind use only (and cannot be retrofitted for water use). The biggest wind generator builder, or so they claim having sold 100,000 units world-wide, is the American company South West Wind Power, possibly better known here as the manufacturer of the AirX, now replaced by the WindBreeze, one of the three-blade units. The WindBreeze comes in various sizes.

Australian suppliers

There are a number of suppliers in Australia, some of whom supply from a number of competing manufacturers:

• RW Basham, www.rwbmarine.com.au

• Applied Solar Wind Solutions, www.appliedsolarwindsolutions.com.au

• Wind Energy and Solar Power, www.energymatters.com.au

• Neosid, sales@neosid.com.au (for LVM products only)

It is obviously also possible to buy on the internet, where some prices offshore make some Australian pricing look profitable.

Prices

The most expensive unit, by far, is the Eclectic Energy Duo Gen at around $6000 (but this includes the tower or pylon – prices vary slightly dependent on the height of the pylon needed), which is a hybrid unit and produces about 17 amps at 25 knots windspeed and around 10amps at seven knots boat speed. The hybrid LVM, A4A, produces eight amps at 25 knots wind speed and eight amps at seven knots boatspeed. (We could not get an Australian price for the hybrid Ampair product).

For standalone wind units prices exwarehouse in Australia: Eclectics D400, costs $3800 (25 knots wind 23 amps); LVMs A4 (same base units as the A4A) $2200, LVMs A6 $3600 (25 knots wind 15 amps); Ampair 100 $1450 (this is the same base unit as the hybrid, (25 knots wind seven amps) and the Air Breeze 200, $1450 (20 knots wind 16 amps). If we were buying a standalone wind unit and had an unlimited budget, we would buy the largest, in terms of power production, wind generator we could find. These big units can generate enough electricity to power a small house, but you might need to anchor in a slightly exposed area to enjoy the full benefits. The big units include LVMs Aerogen, Eclectics D400 or one of the big Airbreeze models.

Hedging your bets

Realistically you really need to think of hedging your bets. But if you are prepared to be flexible, harnessing the wind to view a DVD has an enormous amount of logic.