True vs MSI MAP

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.

Bring your passage into the app, keep only the navigational warnings that actually touch it, and carry them over to the ECDIS. NAVAREA and coastal NAVTEX warnings are plotted on a world map whose coastline is bundled inside the app — no tile server, and the last warnings you pulled stay readable with no connection. WARNINGS ALONG YOUR ROUTE — MSI PRO · Import a route file (RTZ, GPX, CSV or JSON) and see it drawn under the warning pins · Keep only the warnings within 100, 200 or 300 nm of that route and clear the rest away · Re-fetch every source on demand, instead of the free once-daily cycle EXPORT TO THE ECDIS — MSI PRO Warnings are carried over as latitude/longitude lines with text marks, ready to open on the bridge. · JRC user map (.uchm) — native format · GPX · Furuno user chart (beta) WARNING SOURCES · NGA — worldwide NAVAREA plus HYDROLANT, HYDROPAC and HYDROARC · Coastal NAVTEX, collected automatically from seven countries — the United States (USCG), Australia (AMSA), Japan (JCG/MSIL), Taiwan (MOTC), Hong Kong (Marine Department), Finland (Traficom) and Denmark (DMA Niord) · NAVAREA III — Spain (IHM) · Korea (KHOA) — collected as well once you enter your own free data.go.kr service key in Settings THE MAP · Fully offline vector coastline at three levels of detail, three bathymetry bands, national boundaries and 167 place labels covering major ports, straits and canals · Coordinates and areas are extracted from the warning text and drawn as points, circles, polygons and tracklines · Filter by NAVAREA, by geometry type, and by NAVAREA versus coastal NAVTEX · Place and port search in English, with no network call · Your own GPS position on the chart CHANGE HISTORY Compares each refresh with the one before it and lists what is new, what was cancelled and what changed. DEPARTURE BRIEFING SHEET Print the current list to an A4 PDF. Free. MSI PRO IS A ONE-TIME PURCHASE Not a subscription. Restores on a new device with Restore Purchase under the same store account. The map, the warning list, the change history and the briefing sheet are free. LOCATION GPS is read only when you tap the my-position button, and only while the app is in the foreground. It is used solely to draw your own position on the chart on this device — it is never sent to a server, never stored as a history, and never collected in the background. Decline the location permission and everything else keeps working. There are no push notifications. Refresh is checked when you open the app or return to it. English and Korean. Note — for reference only. Not for navigation. Not a substitute for GMDSS receiving equipment or official notices to mariners.