Wind generators have been on cruising boats since the 1970s, and they generate more debate per amp produced than almost any other piece of equipment. Advocates swear by them; critics point out that a few extra solar panels cost less, produce more, and do it without noise. Both positions are partially right, and the truth depends heavily on where you sail and how you sail.
The starting point is understanding the physics, because the marketing numbers for wind generators are deeply misleading if you don't.
How Wind Generators Work — and Why the Spec Sheet Lies
A marine wind generator is a horizontal-axis wind turbine (HAWT) — three blades, usually 0.9 to 1.2 meters in diameter, driving a permanent magnet alternator. The output connects to the battery bank through a charge controller (some units include this, others require a separate unit).
The critical physics: wind power scales with the cube of wind speed. Double the wind speed and you get eight times the power. This means that a generator that produces meaningful output at 20 knots produces very little at 10 knots — not half as much, but one-eighth as much. Wind generators live or die by whether you have sustained wind in the 12–25 knot range. Below 10 knots, most units produce negligible output. At 5 knots — a calm anchorage on a summer afternoon — they're essentially decorative.
The rated output (400W for a "400W wind generator") is the output at a specific high wind speed — typically 28–35 knots, depending on the manufacturer's chosen test condition. A boat swinging at anchor in a 28-knot anchorage is not a comfortable situation, and most owners don't spend much time there. The honest operating range is 12–20 knots, and in that range a "400W" generator might be producing 40–120W — or 3–10A at 12V.
Output in Practice: Real Numbers
Aggregated over a full 24-hour period — including the light morning air, the afternoon sea breeze, and the quiet night — a typical wind generator in a breezy anchorage produces 15–25Ah per day. In a genuinely consistent 15–20 knot anchorage (a trade-wind location, an exposed anchorage in the Azores, a Scottish harbor in autumn), this can rise to 40–60Ah per day. In a calm Mediterranean anchorage in July, you'll get 5Ah or less.
On passage in consistent trade winds — the North Atlantic trades at 15–20 knots, the South Pacific trades at 15–25 knots — a wind generator running continuously day and night can produce 100–150Ah per 24 hours. This is where wind generation is most valuable: the trades produce consistent apparent wind from a predictable direction, night and day, that solar can't match. A boat making an Atlantic crossing with adequate solar for daytime needs and a wind generator for overnight charging is genuinely well-equipped.
To put these numbers in context against solar: a single 200W rigid solar panel in good conditions produces 70–100Ah per day. For roughly half the cost and with zero noise, that single panel outperforms a wind generator in most anchorages most of the time. The argument for wind generation is not that it beats solar per dollar; it's that it produces when solar doesn't — at night, in overcast weather, and in the high-latitude overcast conditions where solar panels underperform significantly.
The Noise Problem
This is the issue that causes owners to remove wind generators, and it's underreported in the literature. A wind generator at anchor in 20 knots makes noise. The blades generate aerodynamic noise — a whistle or hum — and the generator creates vibration that transmits through the mounting structure into the boat. The degree varies significantly by brand and installation, but no production wind generator is silent at speed.
The noise matters because boats at anchor are quiet. People sleep with hatches open. Neighbors on adjacent boats can hear your wind generator. A unit that sounds tolerable during a day sail can make sleep impossible at anchor in a 20-knot anchorage — which is exactly when it would be producing its best output.
The Superwind 350 (manufactured in Germany by Superwind GmbH) is the quietest production marine wind generator in current production. Its blade design produces less aerodynamic noise at speed than competing designs, and its mounting provisions are better engineered for vibration isolation. It is significantly quieter than the AIR-X Marine (now discontinued but common in the used market), the Rutland 914i, and most other production units at equivalent wind speeds. It is not silent — nothing is — but owners who have run multiple wind generators consistently rate it as the least disruptive. At approximately $1,200–1,400 for the unit alone, it's expensive. If noise is going to determine whether you actually run the unit, spend the extra money.
The Rutland 914i is a popular British unit with a strong track record, competitive pricing (around $800–1,000), and decent parts availability. It's noisier than the Superwind at high wind speeds but quieter than older Air-X units. Acceptable for some installations, borderline for others depending on anchorage location relative to neighbors and interior noise transmission.
The Air Breeze (Southwest Windpower's marine version of the Air-X) has a history and a following, but audible noise at 20+ knots is a documented complaint. Not the first choice if quiet operation matters.
Installation Requirements
Stern arch or dedicated pole: wind generators require mounting 6 feet or more above deck level — the blades need clearance from the deck, the boom, and anyone standing in the cockpit. The standard installation is on a dedicated pole on the stern arch. A well-engineered stern arch (steel or stainless, welded, through-bolted to the stern) is a prerequisite. A light aluminum bimini frame is not adequate for wind generator loads — in 30 knots, the lateral and vertical loads from a spinning generator are significant, and the mounting structure must be engineered accordingly. If your boat doesn't have a suitable arch, the cost of building one is part of the installation budget.
Blade clearance: beyond deck clearance, blade tips need clearance from backstays, solar panels, antennas, and anything else on the stern. The spinning diameter of a typical marine turbine is 1.1–1.4 meters. This must be clear of all obstructions in all conditions, including the moments when the boat swings at anchor and the apparent wind direction rotates through 360 degrees.
Blade replacement: blades are consumable. UV exposure, salt spray, and the fatigue loads from constant rotation degrade blades over time. Plan to replace blades every 5–7 years in typical use, sooner in tropical high-UV environments. Rutland and Superwind both sell replacement blade sets; availability for older or discontinued models can be challenging. Verify that replacement parts are available before buying a used generator.
Wiring and charge controller: the cable run from the generator to the charge controller is typically 8–12 meters on a cruising boat. At the current levels a wind generator produces, wire sizing matters — use marine-grade tinned copper wire sized to minimize voltage drop. Most modern wind generators include a dump load controller (also called a divert load controller): when the battery bank is full, the controller diverts generator output to a resistive load (often a water heater element) rather than disconnecting the generator, which would cause it to overspin in high winds. The dump load is part of the system and must be properly installed.
Solar Plus Wind: The Complementary Case
The strongest argument for wind generation is not wind versus solar but wind plus solar. The two sources are genuinely complementary:
- Solar produces when the sun shines; wind generates at night and in overcast conditions.
- Calm anchorages are usually calm because there's no wind — solar conditions may be good; wind generation is poor. Windy anchorages have cloud cover — wind conditions may be good; solar is diminished.
- On passage in the trades, both systems run simultaneously and combined output can cover a heavy passage-making electrical load without running the engine at all.
- In high latitudes with extended overcast — Patagonia, Scotland, Newfoundland — solar underperforms significantly and wind generation becomes relatively more valuable.
A cruising boat making the circuit through the tropics and into high latitudes benefits from both. A boat that stays in the Mediterranean or the US East Coast through summer, where sun is abundant and trade winds don't exist, gets much less incremental value from adding wind to an adequate solar system.
Does the Math Work Out?
A Superwind 350 at roughly $1,300, plus installation hardware, wiring, and dump load — call it $1,800–2,200 installed — producing an average of 20–30Ah per day in mixed conditions over its 10-year service life. Compare to an additional 200W Renogy solar panel at $120–150, installed on an existing arch, producing 60–90Ah per day in similar conditions.
On pure cost-per-amp-hour basis, the solar panel wins unless you're sailing in conditions where wind generation has a specific advantage — consistent trade-wind passages, high-latitude sailing, or extended periods in breezy anchorages where overcast weather limits solar. For most cruisers spending most of their time in the tropics and subtropics, wind generation alone does not make economic sense.
Where it does make sense: the offshore passage-maker with a genuine solar deficit at night on long passages; the high-latitude cruiser in the Azores, Scotland, or Patagonia; or the sailor who simply wants redundancy in their charging system and isn't optimizing purely on cost per amp-hour. For those use cases, a quality wind generator is a legitimate investment. For the average coastal cruiser in the sunny latitudes, invest in additional solar first.