Windy alternative for sailing
Windy shows you the weather.
It doesn’t know where the water is.
We use Windy. Everyone uses Windy. It’s the most beautiful weather map on the internet and the free model-comparison view is better than things people charge for. But it has no depth contours, no fairways, no buoyage, and its routing arrives via a community plugin carrying about 23 stock polars. Keep Windy. Add a solver that can see the seabed.
The short answer
Is Windy good enough for sailing weather routing?
For understanding the weather, Windy is excellent and free. For weather routing, no, and the reason is structural rather than a missing feature. Windy isn’t a nautical chart. It has no depth or hazard data, so any route computed on top of it can’t know about a shoal, a wind farm or a traffic separation scheme. Routing itself isn’t first-party: it comes from a community plugin, Passage Planner, which ships around 23 polar diagrams and which YACHT’s test found producing loops and figure-eights the underlying weather didn’t explain.
OpenSail solves the passage against GEBCO 15-arc-second bathymetry and OpenStreetMap coastlines, segment by segment, using your own boat’s polar. It runs free for one route a week and $59/yr unlimited.
The honest recommendation isn’t to switch. It’s to keep Windy for what it is superb at, which is showing you the atmosphere, and add something that turns that atmosphere into a decision about your boat.
- Windy routing
- Community plugin, ~23 stock polars
- Chart data in Windy
- None — no depths, fairways or buoyage
- OpenSail depth check
- Every segment vs GEBCO 15″ and your draft
- Cost
- Windy free / ≈€19 · OpenSail free / $59 per year
Pick OpenSail if
You need a route your boat can actually sail, with depth, land and your own polar enforced, and a recommendation you can act on.
Pick Windy if
You want the finest weather visualisation there is, forty layers, free model comparison, and you’re content to do the routing in your own head.
Competitor prices and features read from the vendors’ own pages on . Every source is linked at the foot of this page.
The gap
A map of the sky isn’t a map of the sea
This is the whole argument, and it isn’t really a criticism of Windy. Windy set out to build the best weather visualisation on the planet and it did. Nobody at Windy ever claimed to be a chart plotter.
The trouble is that a routing plugin sitting on top of a weather map inherits everything the weather map doesn’t know. And what a weather map doesn’t know is where the bottom is.
Twenty-three polars is the detail that sticks with us. There are more than twenty-three production cruising designs in any decent-sized marina. If your boat isn’t one of the twenty-three, the plugin routes a boat that isn’t yours, and every arrival time and departure recommendation downstream carries that error forward without saying so.
Every segment of a returned route is checked against GEBCO 15-arc-second bathymetry and your entered draft. Not the waypoints. The line between them.
OpenSail checks depth on every segment of the route it hands back, against your entered draft, using GEBCO 15-arc-second bathymetry that resolves to roughly 460 m cells near the coast. Where depth isn’t trustworthy, the segment says so instead of pretending. The same geometry gets checked against OpenStreetMap coastline polygons, so a leg can’t clip a headland between two otherwise legal waypoints.
The engine
What a real solve looks like
Windy shows you a field. A solver searches it. Those are different verbs and the second one is much more expensive, which is why it isn’t a plugin.
OpenSail expands time-layered reachability fans in native Rust. Each ring is everywhere your boat could be after another three hours, given her polar, the forecast at that hour, the current, and the water under her keel. A typical crossing burns half a million candidate states and throws almost all of them away.
A weather map
A rhumb line and your judgement. Which is fine, until the judgement is being made at 0300 by someone who has been awake for nineteen hours.
OpenSail’s solver
Each ring is everywhere the boat could be after another three hours, given her polar, the forecast at that hour, the current, and the depth under her keel. The route is the cheapest path through nine of them. Figures from a real Tampa Bay → Nassau solve.
Then it does it again three more times, with different comfort weightings, and tells you which of the four to take and what the other three would have cost you. Fastest across the Gulf Stream in 24.9 hours with 21 degrees of heel, or family mode 2.6 hours later behind the front with the heel halved. That’s a decision, not a layer.
How Compare All Modes works · How the departure planner works
The other side
Model comparison, done two ways
Windy’s compare view is the feature we would steal if we could. Flipping ECMWF against GFS against ICON against AROME, free, in one interface, has probably prevented more bad passages than any paid product on this page.
The thing it leaves to you is the interpretation. You’re looking at four maps and deciding, by eye, whether the difference between them matters where you’re going. OpenSail asks a much narrower version of that question and answers it numerically: re-sample two models at your route’s own positions and times, through a single interpolator, and report where and when they part company.
Both models re-sampled at your route’s own positions and times, through one interpolator, so the difference you see is the models disagreeing rather than two apps rounding differently. Illustrative trace from a Gulf Stream crossing.
“They disagree somewhere in the Atlantic” is interesting. “They agree until 0300 Thursday and then split fourteen knots, forty miles before your waypoint” changes what you do. Neither approach is wrong. They answer different questions, and if you only want the first one, Windy already does it for free and you should not pay us.
Line by line
OpenSail vs Windy, capability by capability
| Capability | OpenSail | Windy.com |
|---|---|---|
| Weather routing included at the entry paid tierWhether you can get an optimised route without buying the top of the price list. | ●$59/yr, unlimited | ◐Community plugin |
| Free tier that solves a real routeWhether you can test the actual solver before paying, rather than only viewing forecasts. | ●1 route/week | —No routing |
| Per-segment depth verification against bathymetryWhether every leg of the returned route is checked against charted depth and your draft, rather than the grid being sampled at waypoints. | ●GEBCO 15″, per segment | —No chart data |
| Comfort as a first-class routing objectiveWhether you can ask for the passage your crew will tolerate instead of only the fastest one. | ●4 modes incl. Family | —Plugin is time-only |
| Editable polars for your own boatWhether the route assumes your boat’s performance or a stand-in from a small library. | ●Editable + catalogue | —~23 stock polars |
| Model disagreement measured along your routeWhether the app tells you where two independent models stop agreeing on your track, or leaves you to flip between tabs. | ●Verdict + band | ◐Compare by eye |
| Says why it refused a routeWhether a failed solve explains the constraint that stopped it or returns nothing. | ●Structured refusals | —not offered |
| Plain-language briefing on which route and when to leaveWhether the app commits to a recommendation and shows its reasoning, or hands you a table. | ●Intelligence Layer | —not offered |
| Anchorage exposure scored hour by hourWhether you can check tonight’s anchorage for the sectors it is open to, in the same app that planned the passage. | ●In the map | —not offered |
| Alerts you when a new model run worsens a planned routeWhether you stop re-checking the forecast manually once a passage is planned. | ●Threshold-gated | ◐Point alerts |
| Runs in a browser with no installWhether crew, delivery skippers and shore support can open your plan on whatever machine is in front of them. | ●PWA, installs optional | ●Full web app |
| Documented public APIWhether you can pull routes into your own dashboard, race committee tooling or boat systems. | ●REST, keyed | ＄Paid, limited |
| Pause the subscription for haul-outWhether you pay for the months your boat is on the hard. | ●Built in | —not offered |
● included◐ partial or workaround＄ costs extra— not offered
The other side
Where Windy wins
Where Windy.com is the better buy
Written by us, about them. If one of these describes your boat, buy theirs — you will be happier and we would rather you came back later than churned in a month.
- It is the best-looking weather visualisation anyone has built, and the particle animation genuinely teaches you what the atmosphere is doing.
- Model comparison — ECMWF, GFS, ICON, AROME side by side — is free, fast and excellent, and a lot of sailors' entire weather workflow is this and nothing else.
- Free covers more than most people need for day sailing and coastal hops in settled weather.
- Radar, satellite, webcams, airport metars, waves, swell trains: the layer catalogue is enormous and it’s all one map.
And one that’s hard to quantify: Windy taught a generation of sailors to read a forecast. The particle animation isn’t decoration, it’s a teaching tool, and a lot of people understand gradient wind and sea breeze because they watched it move. We’re building on ground Windy cleared.
Questions sailors actually ask
Can Windy do sailing weather routing?
Not as a first-party feature. Routing arrives through a community plugin called Passage Planner, which runs isochrone expansion over Windy’s forecast data. When YACHT tested it on a Baltic passage it produced routes with loops and figure-eights the underlying weather didn’t explain, and it ships with roughly 23 polar diagrams, so most boats get routed as an approximation of a different boat. The deeper limitation is that Windy isn’t a chart, so a computed route has no idea what is under it or around it.
Should I stop using Windy if I get OpenSail?
No, and we would think less of the advice if it said otherwise. Windy is the best weather visualisation anyone has built and the model-comparison view is free and excellent. Keep it. Use Windy to understand what the atmosphere is doing this week; use OpenSail to decide what your boat should do about it. Almost everyone on our team has Windy open in another tab right now.
Is Windy Premium worth it for sailors?
For about €19 a year, if you sail regularly, probably yes. The main upgrade is hourly forecast steps instead of three-hourly, which matters for timing a frontal passage or a sea breeze. Just be clear on what you’re buying: Premium is a better weather map, not routing. If your question is “which line do I sail and when do I leave”, Premium doesn’t answer it and no amount of layers will.
Does OpenSail have Windy’s animated particles and layers?
The wind particle layer, yes, rendered on the GPU through MapLibre with the same zoom-adaptive density trick. Waves, gusts, pressure, currents and a squall-risk layer built from surface CAPE, yes. Windy’s full catalogue of radar, satellite, webcams, airport metars and everything else, no. They have a decade’s head start on layer breadth and we aren’t chasing it, because a sailor doesn’t need forty layers. They need to know whether Thursday works.
What does OpenSail cost compared with Windy?
Windy is free, and Premium is about €19 a year. OpenSail is free for one real solved route a week, then $59 a year for unlimited routing with all four comfort modes and the departure planner. They aren’t really competing purchases. One is a weather map, the other is a decision tool, and plenty of sailors pay for both without feeling robbed.
Does OpenSail compare forecast models like Windy does?
It goes further, in one narrow way. Windy lets you flip between ECMWF, GFS, ICON and AROME and judge the difference by eye, which is a good tool and a fair amount of squinting. OpenSail re-samples two models at your solved route’s own positions and times, through one interpolator, and gives you a verdict with the hour the agreement breaks down. That’s a smaller question than Windy answers, asked much more precisely.
Where these numbers come from
Every competitor price and feature on this page was read from the vendor’s own page or a named independent test. Last checked . Prices change; if you find one of these out of date, tell us and we will fix it.
- YACHT — Windy Passage Planner weather routing in testPlugin polar count, implausible route geometry, and the absence of chart data.
- Windy Community — Windy Premium featuresPremium price and the hourly-versus-three-hourly forecast step.
PredictWind, savvy navvy, Windy.com and LuckGrib are trademarks of their respective owners. OpenSail is not affiliated with, endorsed by, or sponsored by any of them. Comparisons describe publicly documented capability at the date above.
Compare something else
Keep the map. Add the decision.
Leave Windy open in the other tab. Solve one passage here with your own boat’s polar and see whether the route it returns is one you would have drawn.
Plan a passage — freeFree account, no card. If it doesn’t beat what you use now, close the tab. We won’t email you about it.