The Digital Pilot Chart for
Offshore Passage Planning
Horizory is a free sailing route planner built on 10 years of global wind climatology. Plan cruising routes, compare departure months, and stress-test your passage against the statistical wind picture — all on an interactive map.
What is Horizory?
Horizory is a free digital pilot chart and sailing route planner for offshore passages. It shows the statistical distribution of wind directions and Beaufort strengths for every ocean grid point and every calendar month — based on 10 years of global atmospheric reanalysis data.
The concept is directly inspired by the classic NGA Pilot Charts — the paper atlases used by offshore navigators for over 150 years. Horizory takes that same climatological data and makes it interactive: click anywhere on the ocean, pick a month, and instantly see the statistical wind picture at that location. Trace a route, compare departure months, ask "what if I leave two weeks later?" — all on one map, without touching a printed chart.
It is built specifically for planning cruising routes weeks or months before departure — not for real-time routing or weather forecasting.
What are Pilot Charts — and Why Go Digital?
Pilot Charts are monthly climatological atlases published by the US National Geospatial-Intelligence Agency (NGA). Each page shows a particular ocean for a given month, with wind roses drawn at regular grid points. Each wind rose conveys the observed wind direction frequencies and typical Beaufort strengths over decades of shipping log data.
Offshore sailors use them when planning cruising routes to choose the best departure month, avoid gale seasons or hurricane zones, and find the trade wind corridors that make downwind ocean crossings possible. The Atlantic pilot charts, for example, make it immediately clear why most sailors doing an Atlantic crossing sail from the Canary Islands to the Caribbean in November or December — the northeast trade winds are reliable and the hurricane season has ended.
The limitation of the classic pilot charts is that they are static. You cannot overlay your own route, compare two departure dates, or ask which waypoints along your planned track look concerning for a specific month. A digital pilot chart solves exactly that — and that is what Horizory is.
Route Planning Features for Offshore Sailors
Wind Rose Map
Interactive wind roses at ~20,000 ocean grid points. Select any month with the slider — the entire map updates instantly.
Sailing Route Planner
Place waypoints on the map and get the Beaufort distribution and wind angle statistics for each leg, for your chosen departure month.
ETA Estimation
Upload your boat's polar diagram and the app estimates the most likely passage duration for each leg based on the expected wind distribution.
Ocean Currents
Animated current overlay showing monthly mean direction and speed across the global ocean.
Storm Tracks
Historical tropical cyclone paths from over 40 years of official records, color-coded by intensity. Separate risk zone overlay for quick assessment.
Hazard Zones
Overlays for piracy risk areas, orca interaction zones, and gale frequency zones — all derived from official and open-access datasets.
Ports of Entry
~5,000 ports worldwide from the World Port Index database, shown as map markers with basic port information.
GPX Export
Export any planned route as a GPX file for use in Navionics, OpenCPN, B&G, Garmin, and other navigation software.
The Data Behind the App
All data in Horizory comes from open-access scientific and governmental datasets — the same sources used by professional meteorologists and oceanographers.
The wind statistics are built from 10 years of hourly global reanalysis data. For each ocean grid point, all hourly observations in a given calendar month across those years are pooled, then binned into 8 compass sectors and 10 Beaufort classes. The result is a frequency table that sums to 100% — the same information a traditional pilot chart conveys in a single wind rose, but now queryable for any point on the globe.
Ocean currents are derived from a global ocean reanalysis, averaged to a monthly climatology. Storm tracks are taken from an international best-track database spanning over 40 years of official tropical cyclone records. Port data covers approximately 5,000 ports worldwide from a standard maritime reference database. Hazard overlays (piracy zones, traffic separation schemes, offshore windfarms) are based on open maritime datasets.
Frequently Asked Questions
What is a digital pilot chart?
A digital pilot chart is an interactive, browser-based version of the classic paper pilot charts published by national hydrographic offices. Where the traditional charts show static wind roses printed on paper for a given ocean and month, a digital pilot chart lets you query any point on the globe, overlay your own route, and compare months dynamically.
Horizory is a digital pilot chart built on 10 years of global wind climatology. It shows the same statistical wind information as the classic NGA charts — direction frequencies and Beaufort distributions — but on an interactive map you can explore freely.
How do I start planning a cruising route?
Open Horizory and use the month selector at the bottom of the screen to pick your intended departure month. Then click the route planner icon to start placing waypoints. Each leg of your route will show the expected wind angle and Beaufort distribution based on historical climatology for that month.
A good starting point for planning cruising routes is to first check the wind rose overlays along your intended track. Areas where the roses are large and consistently pointing one direction signal reliable, predictable winds — exactly what you want for offshore passage planning.
Is Horizory free to use?
Yes. All features — wind rose map, route planner, storm tracks, current overlay, polar-based ETA estimation — are completely free. No account is required to use the app.
What is the difference between Horizory and a weather forecast app?
Horizory shows climatological statistics — what the wind has historically looked like in a given month, averaged over 10 years. It tells you what to expect on a statistical basis.
A weather forecast app (PredictWind, Windy, etc.) shows the actual predicted weather for the next 7–16 days. You need both: Horizory for planning months in advance, a forecast app when you are ready to go.
When is the best month to cross the Atlantic from Europe to the Caribbean?
The classic departure window from the Canary Islands is late November through January. By that point the Cape Verde hurricane season is over, and the northeast trade winds are well established. Most ARC (Atlantic Rally for Cruisers) participants depart Las Palmas in late November for exactly this reason.
Departing in October risks encountering late-season Atlantic hurricanes. Departing in February or March is also possible, but the trade winds are statistically less reliable.
Open Horizory, click on the ocean south of the Canary Islands, and compare the wind roses for October, November, and December side by side — you will see the difference immediately.
How do I plan a route in Horizory?
Click the route planner icon in the top-left corner of the map. Then click on the ocean to place waypoints — each click adds a stop. The app draws the route and shows wind angle and Beaufort statistics per leg for the selected departure month.
If you upload your boat's polar diagram (a CSV file with boat speed by true wind angle and true wind speed), the app will also estimate the expected passage time for each leg.
What is a polar diagram and how do I use it in Horizory?
A polar diagram describes a sailing boat's performance: for a given true wind speed and true wind angle, it shows the expected boat speed through the water. It is usually supplied by the boat builder or can be measured empirically.
In Horizory, you can search for your boat in the built-in database of polars, or upload a custom CSV. The app then combines the polar with the climatological wind distribution to estimate the most likely passage time for each leg of your route.
Can I use Horizory to plan a Pacific crossing or circumnavigation?
Yes. The wind data covers all global oceans. The route planner works anywhere — Pacific, Indian Ocean, Southern Ocean. You can plan a full circumnavigation by placing waypoints around the globe and checking the wind statistics for each leg at your intended departure month.
How accurate is the wind data?
Horizory uses a state-of-the-art global atmospheric reanalysis that assimilates billions of observations from satellites, ships, buoys, and weather stations. It is widely considered the most accurate freely available historical wind dataset for open ocean areas.
At Horizory's grid resolution of roughly 150 km, local coastal effects, island wind shadows, and squalls are not captured. For open ocean passage planning, the accuracy is excellent. For coastal sailing and harbor approaches, always consult higher-resolution local forecasts.
Where can I report a bug or suggest a feature?
Send bug reports and feature requests to feedback@horizory.com.
Ready to plan your passage?
No account needed. Open the app and start exploring wind statistics for any ocean and month — right now.
Open Horizory →