Marine wind turbines

A wind turbine converts mechanical energy into electrical energy through the force of the wind. The rotation of the blades turns a generator that operates on the same principle as an alternator. The power delivered is proportional to the speed of rotation.

A wind turbine produces a significant amount of current that will help offset a large part, if not all, of the onboard consumption. Regardless of the month of the year, the wind turbine provides significant energy. Production is naturally higher during the winter months when there is more wind. Wind energy thus naturally complements solar energy, which provides more energy during the summer period.

There are 2 main types of marine wind turbines

Horizontal wind turbines

Wind turbines operating on a horizontal axis are the most common and especially the most powerful. For substantial wind energy production, large diameter blades are required (around one meter). Smaller wind turbines are generally intended for maintaining battery charge. The Aerogen wind turbine range covers all needs (version 2 produces 1.3A at 20 knots and thus maintains battery charge, while version 4 compensates for average onboard consumption with a production of about 6A at 20 knots, and for fully autonomous travel, version 6 will give you about 10A at 20 knots). Another high-power wind turbine, the D400, can meet all onboard consumer needs, specially designed to deliver high amperage with low wind speeds (thus it provides 91 amps per day with only 9 knots of wind). Finally, there are combined hydrogenerators/wind turbines DuoGen, an interesting solution for long downwind crossings when relative wind is lacking, you can convert the wind turbine into a hydrogenerator in a few seconds (see our 'hydrogenerator' file) and switch it into the water. The performance delivered both as a wind turbine and as a hydrogenerator by these combinations is excellent and easily compensates for all onboard consumers.

Vertical wind turbines

Even though they have lower efficiency (see ATMB vertical wind turbines sheet), they have the advantage of being very easy to mount on the mast, with minimal space requirements, they pose no danger, and the risk of entanglement with a halyard is very low. Additionally, they can continue to spin even in a storm because beyond a certain wind speed, excess air is expelled as vortices above the wind turbine. They are generally used for maintaining battery charge (the small model delivers 0.6A at 15 knots while the large one generates 1.5A at the same speed), furthermore, as the voltage does not rise above 12.8V, it will not be necessary to add a charge regulator, which represents a significant saving.

Finally, to fully exploit wind energy, special attention must be paid to:

• the location for installation to avoid dangers (blades away from halyards and crew heads),

the basic assembly rules to avoid noise-related inconveniences

• the regulation to have a completely autonomous system.

Location and installation of a wind turbine on a boat

As a general rule, the wind turbine will work better away from the sails and at a certain height. The rear arch is therefore an ideal location. But care must also be taken to ensure it is not overhanging the solar panels (due to shadows). There are many mounting kits available to suit your needs.

The most frequent criticism of wind turbines is noise, often caused by poor installation or a low-quality product.

There are two types of noise:

• Aerodynamic noises (depend on the wind turbine).
• Mechanical noises (depend on the assembly).

Aerodynamic noises are caused by the air escaping over the trailing edges of the blades. To avoid these noises, it is preferable to choose wind turbines that limit their rotation speed (the faster they spin, the noisier they are).
Mechanical noises come either from internal friction of the rotating shafts or from vibrations transmitted by the mast to the boat.

Internal friction can be controlled by regular maintenance (lubrication, tightening, cleaning). As for vibrations, they can be greatly reduced if the mast is mounted on silent blocks.

Nevertheless, a wind turbine always produces a slight noise when it turns, so at anchor, consider the neighbors and stop the blades, at least during the night, if your batteries are not too discharged.

Electrical connection:

The electrical connection is very simple because only two wires need to be connected. Since the power of a wind turbine is variable, it is necessary to use a regulator to avoid overloading the batteries or to make the best use of the available energy (except for some vertical wind turbines that do not require a voltage regulator). Depending on the models, the regulators are either integrated or separate from the wind turbine. In the first case, the connection will be made directly to the batteries, and in the other case, the connection will be made to the regulator. This type of mechanism allows, for example, to power a device (typically lighting) when the batteries are fully charged. This way, excess energy is not wasted.

Storage and use of the produced energy:

The storage is done in one or more batteries (also see on our site: How to choose a battery / Battery connections / Cable choices for batteries).

Note: If necessary, a converter transforms the direct current (12V or 24V) from the batteries into alternating current (220/230V).