True vs Binnacle

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.

Binnacle is a set of bridge instruments for merchant marine deck officers. Thirteen tools, most of them working with no signal, and none of them pretending to be more certain than it is. ON WATCH • Navigational warnings, plotted. NAVAREA and the coastal services drawn on a chart where they actually are, instead of read as a wall of text at three in the morning. Set a radius from your position and follow only the services that concern the passage. • Weather for a position and a time you choose — wind in forces, the barometric tendency, fog risk. Forecast data from MET Norway. • True wind from course, speed and apparent wind. • Manoeuvring board — CPA and TCPA for two to five contacts at once, and one alteration that clears all of them. POSITION AND CHECKS • Compass error by amplitude or azimuth, worked against celestial data for the moment you observed. • Celestial fix — reduce two or three sights and see the cocked hat plotted, with its residuals, not just a number. • ETA and passage timing in UTC, with the arithmetic shown. • Heel, trim and roll period from the phone's own sensors, with GM estimated from the roll period. RECORDS AND REFERENCE • Log book for bridge events, kept for the whole contract and handed over as a PDF. • 17,998 ports by UN/LOCODE, and 11,728 port facilities with their GISIS codes, searchable by name or code — the reference is bundled, so it works alongside. • Manoeuvring miles — passage legs with sea and manoeuvring totals kept apart. • Unit converter for the units a bridge actually uses: knots, cables, fathoms, hectopascals, tonnes and the rest. WHAT IT WILL NOT DO It is an aid, not an authority. It does not replace corrected charts, official publications, the ship's procedures or the officer's judgement. Every screen states its own limits rather than hiding them, and every export says on its face what it is. WHAT STAYS FREE True wind, ETA, compass error, the manoeuvring board, heel and trim, weather and the unit converter are free, with no limit and no trial. The log book keeps ten entries free. Celestial reduces one sight free. Port search and the match count are free. ONE PURCHASE, NOT A SUBSCRIPTION • Navigational warnings — NAVAREA and the coastal services, with the chart and the radius • The facility's own record in Port Facilities • Fixes from two or three lines of position, and the plot • PDF export, on every screen including the free ones One payment of $5.99 unlocks all of it, on every device signed in to your Apple Account. There is no subscription, nothing renews, and there is nothing to cancel. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy and Terms are also in the app, under More.