Sailboat wind sensors: mechanical or ultrasonic, the real match

By Pol Conin — Skysat, marine electronics workshop in Carnac, France. Revised and corrected September 2nd, 2026.

Why the wind sensor matters so much

The wind sensor feeds the whole decision chain: wind-mode autopilot, true wind, polars, sail choice. An imprecise or delayed measurement propagates to every downstream indicator — a pilot weaving upwind, incomparable polars, sail calls by guesswork. It is the instrument where installation and calibration quality pay back most.

Mechanical vane sensors: the reference from cruising to racing

The cup-and-vane sensor remains the sailboat's dominant technology, from entry level to IMOCAs — and that is no anachronism: B&G states it chose cups and vane over ultrasonic for its current sensors, after hundreds of wind-tunnel tests.

B&G WS310 (wired) and WS320 (wireless): the standard sensors of the Triton²/NMEA 2000 ecosystem. Same mechanical head, two links — the WS320 removes the mast cable at the cost of an internal battery to monitor. Details and prices on the comparison page.

Vertical B&G WS700 series (WS710 / WS720 / WS730): the same mechanical philosophy on a high-modulus carbon spar of 0.8 / 1.1 / 1.4 m (up to 1.8 m per options), standard or reinforced Ocean specification. The point is not a "different" sensor: it is height, lifting the measurement out of the zone disturbed by mainsail and masthead. This is the typical fit of performance programmes and H5000 boats.

B&G 213: the historic masthead unit of H5000 systems, still in the catalogue with its spare parts — vanes, cups and bearings are replaceable, which explains the longevity of well-serviced units.

nke HR: the high-resolution carbon vane fitted to much of French offshore racing (IMOCA, Class40, Figaro). Skysat's nke catalogue is being reactivated — racing project quotes on request.

The mechanical limits are known and manageable: bearings that wear (periodic replacement), and a 2D measurement in the sensor's plane — hence the importance of verticality and heel corrections (next section).

Ultrasonic: where it makes sense, where it does not

An ultrasonic sensor measures wind by time-of-flight between transducers: no moving parts, no bearings, no mechanical maintenance. The segment's players are specialists such as LCJ Capteurs (CV7) or Calypso Instruments — not the B&G sail ranges above.

Right for: autonomous or compact installs (Calypso offers solar wireless versions), boats wanting zero masthead maintenance, platforms without a disturbing mainsail (motorboats, RIBs, harbour weather stations).

Worth knowing: depending on the model, driving rain and icing can degrade the measurement; housing aerodynamics and position remain decisive; and integration with sailing electronics (calibrations, heel corrections, computer compatibility) is less native than in a full B&G or nke ecosystem. In offshore racing, today's reference remains the high-end mechanical vane on a vertical spar.

Verticality, heel and clean air

Three phenomena disturb masthead measurement: mainsail upwash (wind accelerated and bent by the sail), mast motion in waves (the sensor sweeps through the air; the pilot can read that motion as a wind shift), and heel (the sensor's plane is no longer horizontal).

Serious answers are system-level: a vertical spar moving the sensor away from the sail (WS700 series), heel and motion corrections computed by the processor from the attitude sensor (H5000, nke, MADBrain), and calibration done in real conditions. However good, a sensor alone cannot correct what the system does not measure.

Wireless or wired

Wireless (WS320, solar Calypso): a one-hour install with no mast cable — the retrofit choice where no cable exists. Constraints: a battery to monitor and replace, and a radio link to validate on metal boats or complex rigs.

Wired (WS310, WS700 series, 213, nke): a mast cable run (count an extra half-day of yard work), but permanent power, no battery management at sea and a dropout-proof link — the offshore and racing standard.

5 installation mistakes seen at the workshop

1. Sensor misaligned with the boat's centreline. A few degrees off at 0° = every point of sail skewed, invisible until the first upwind leg where polars stop matching. Alignment is validated at installation, then at sea.

2. Sensor too low, in disturbed air. The zone above the masthead is turbulent: that is the whole point of vertical spars. Otherwise, respect the manufacturer's prescribed mounting height.

3. Signal cable run alongside a power cable. The sensor signal lives badly next to a windlass or starter cable: separate the runs in mast and bulkhead.

4. Commissioning without calibration. Angle offset and corrections are set from the display or app — ten often-forgotten minutes that separate a measurement from an ornament.

5. Ignoring heel on well-canvassed programmes. Without attitude correction at the processor, heel introduces a variable bias. On a boat sailed heeled, heel correction (attitude sensor + processor) is part of the wind system, not an option.

Read next

• Sailboat wind sensor comparison (current prices)
• NMEA 2000: architecture, backbone, terminators
• B&G vs Raymarine autopilots (40-50 ft)
• Electronic compasses and attitude sensors

Disclosure: Skysat distributes B&G, nke, Raymarine, Garmin and Navico. This article is neither sponsored nor reviewed by the brands cited; the mechanical design of B&G's sensors is documented by the manufacturer ("cup and vane design rather than an ultrasonic design").