Wind Instruments

Shop wind instruments at West Marine.

West Marine offers wind instruments and instrument packages from Garmin, Raymarine and B & G. If you are new to wind instruments, read on for a basic understanding of what these devices do.

What Wind Instruments Do

Wind instruments display wind angle and wind speed on a cockpit-mounted instrument. This information is desirable to sailors so they can sail their boats efficiently, know when to reduce sail, and sail more effectively at night. They are occasionally found on powerboats, especially those that cruise or perform race committee duties. Instrument packages are a simplified way to buy three common sailboat instruments: a knot log, depth sounder and wind instrument. The primary function of wind instruments is to show the boater what the wind speed and wind angle is. By knowing this information, a boater can select the right sails and trim them more effectively.

Apparent Wind versus True Wind

There are two types of wind that are of interest to sailors and to a lesser degree powerboaters. As a boat moves through the water, it creates its own wind. Imagine a boat that is powering on a calm day. The “wind” will appear to be coming from the bow at a speed equal to that of the boat. Similarly, a boat that powers downwind at the speed of the wind will feel no apparent wind. Of course the wind is still there, but the movement of the boat makes the wind’s detection more difficult. The wind you feel as a result of the motion of your boat is called apparent wind, since it appears to be what is happening in the environment.

True wind is what you measure if you sit on an object that is not moving, like the end of a wharf. It is independent of the motion of the boat; and is what is really happening in the environment. All simple wind meters measure apparent wind, since they cannot subtract out the effect of the boat’s movement on the measurements.

Calculation of True Wind Speed

Wind instruments calculate the true wind direction and speed based on your boat’s speed and the apparent wind speed and angle. This is handy when you want to know “how hard it’s really blowing” and when deciding on a sail for the next leg of a race when your direction will be changing substantially.

Digital versus Analog Wind Instrument Displays

Most wind speed indicators consist of a digital display that shows wind speed in knots to the nearest 1/10 of a knot. Wind direction can be displayed using digits (from 0–180° port and starboard) or a pointer that turns through 360°. For direction, some boaters prefer an analog pointer, although digital wind angle is more precise.

Wind Instrument Transducers

Wind instruments display wind speed and direction based on data received from transducers. Most sailboats rely upon a masthead wind transducer assembly that consists of an electronic wind vane that senses the apparent wind angle and a rotating set of wind cups that senses the apparent wind speed. To calculate true wind speed, input from a knot meter is also required. Most sailboats use a paddlewheel style knot meter for boat speed.