The composite wind instrument combines apparent and true wind angles and speeds with vessel heading and course over ground. Its annular face leaves the center mostly transparent so chart content remains visible.

The instrument accepts eleven independently selectable Signal K paths:

The speed-through-water and current paths default to the standard Signal K keys shown above; the others are unset until you map them.

Signal K angles are converted from radians to degrees. Speeds are converted from metres per second to knots. Missing or timed-out values are replaced by dashes without hiding the remaining current data.

The heading input is treated as magnetic and corrected with OpenCPN’s current magnetic variation before it is drawn against the true-north chart.

For the values OpenCPN already fuses for own ship — course over ground and heading — the instrument falls back to OpenCPN’s data whenever the matching Signal K key is left unset or its data has timed out. A configured, fresh Signal K key always takes precedence, so you keep full source control (for example through the SRC: source-lock modes) when you want it, while the instrument still works out of the box without mapping those two paths.

To keep the four readouts legible over busy chart content, each apparent/true column is drawn on a translucent backing panel tinted with the ring color. The thickness of the dial ring itself can be made translucent too via the Ring opacity setting (0 = invisible, 255 = solid) so more of the chart shows through.

In North up mode the compass remains fixed while heading, COG, wind markers, and the port/starboard sectors rotate. In Heading up mode the bow and colored sectors remain at the top while the compass and COG rotate relative to heading. The A and T triangles point inward because wind comes from the indicated direction; heading and COG triangles point outward.

When Show laylines is enabled, two laylines are drawn from the true wind direction in the port and starboard colors. They mark the courses the vessel would make on each tack and the instrument switches automatically between the upwind and downwind set based on the current true wind angle: the close-hauled Beat angle is used when sailing within 90° of the wind, the running Gybe angle when sailing further off. Each angle defaults to a configurable fixed value but is overridden by its Signal K key (performance.beatAngle / performance.gybeAngle, in radians) whenever that data is available. The laylines are drawn over the dial ring but below the wind, heading and COG direction triangles so the markers stay readable.

The Layline reference setting selects what the laylines represent:

The laylines extend a little beyond the dial rim. This overhang is purely visual: the instrument is still positioned and sized by its dial, so the dial center stays on the vessel and neighbouring instruments are laid out as if the laylines were not there. The overhang is likewise ignored by the right-click configuration menu.

The diameter, ring opacity, layline reference, and colors of the face, ticks, text, markers, border, and port/starboard sectors are configurable. The central opening, tick spacing, font sizes, marker geometry, and the label backing panels are fixed.