True vs time+position

The wind you feel on a moving boat isn't the real wind. True-Wind Calculator turns the apparent wind you measure into the true wind you need — in two taps, no wind instruments required. In use since 2013, completely rebuilt in 2026. HOW IT WORKS Enter boat speed, apparent wind speed, apparent wind angle and heading. The app does exact vector math — no lookup tables, no approximations — and gives you true wind speed and true wind direction instantly. Boat speed and heading can be filled automatically from GPS and compass with one tap. FREE • True wind speed, direction and angle — unlimited calculations • One-tap GPS fill for boat speed and heading • The formula explained, so you can trust the numbers • Works completely offline — no account, no ads, no tracking PRO (one-time purchase, no subscription) • Performance — live VMG, target boat speed, % of target VMG and point of sail, driven by your boat's polar • Tactics — tack preview, windward-mark laylines, and whether you can lay the mark • Boat polars — pick a preset or build your own in the editor • Compass rose view — heading, apparent and true wind on one dial • Calculation history — every result logged with its inputs • All speed units — knots, m/s, km/h, mph Bought the app back when it was paid? Pro is already yours — it unlocks automatically. PRIVACY Everything stays on your device. Location is read only to fill the input fields and never leaves your phone. No analytics, no third-party SDKs.

time+position reports the numbers for position, speed, and altitude, if available and as known to your device. If location is turned off or unavailable, the app reports the current time. Units may be set to nautical (default), metric, or statute (miles). All this is completely free, including no ads and no paid upgrades. I developed the app for myself, and am making it available in case there is broader interest. I do not collect any information from this app. This app also offers an option to mark a location and shows the distance from the mark, and the average speed and direction since the location was marked. time+position can display on a red screen to preserve night vision if the app is started at night. Before time+position can be used, users must agree to a disclaimer -- I am not perfect, and neither is this app.